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4 Sensors and Electron Devices Directorate INTRODUCTION The Panel on Sensors and Electron Devices of the Army Research Laboratory Technical Assessment Board (ARLTAB) met to review the Sensors and Electron Devices Directorate (SEDD) at the Army Research Laboratory (ARL) facilities at Adelphi, Maryland, on July 18-20, 2007, and May 28-30, 2008. SEDD contains four divisions, all of which were reviewed by the panel: Electro-Optics and ÂPhotonics, Radio Frequency and Electronics, Signal and Image Processing, and Directed Energy and Power Generation. SEDD is responsible for the Micro Autonomous Systems and Technology Collaborative Technology Alliance (CTA), which was awarded in February 2008. The Computational and Informa- tion Sciences Directorate (CISD), the Vehicle Technology Directorate, and the Weapons and Materials Research Â Directorate also contribute to the management and to the collaborative research conducted in the CTA. SEDD also has responsibility for the sensor information processing research area within CISDâs Network and Information Sciences International Technology Alliance with the United Kingdom that began in 2006. CHANGES SINCE THE PREVIOUS REVIEW There is a broad scope of activities within SEDD, encompassing power sources and electronics; acoustic, magnetic, and electric sensors; advanced radio-frequency (RF) technologies; signal and image processing; and sensor fusion. The breadth and scope of projects in the directorate are appropriate to the mission of SEDD and responsive to the Armyâs needs. There is a good balance between the pressure of near-term deployable technology development and long-term basic research, and there is a clear awareness of this balance among the management and staff of SEDD. SEDDâs discussions of the roles and expected outcomes for the projects, especially those identified as purely technology development, were particularly impressive. The research environment 39
40 2007â2008 assessment of the army research laboratory in SEDD is very positive. There is a level of energy and interest that clearly reflects a positive culture and a strong sense of value in the work that is being done. A healthy, confident culture exists in research activities within SEDD. It appears that a research activity first determines the objective or particular ARL-critical need. Next the ARL internal strength is assessed to determine what resources need to be aligned to conduct the research; identified weaknesses are then strengthened if possible. If the necessary expertise or resources cannot be established within ARL, all technologies that are available and useful are examined around the world. If a desired technol- ogy or capability that is external to ARL is identified, collaboration is sought out among established academic researchers and/or industrial entities. And, finally, if a particular recognized research void still exists, the SEDD staff work with the Army Research Office (ARO) to define appropriate research programs, to create and solicit research proposals, and ultimately to fund research endeavors to fill the needed ARL-critical objectives. This culture was evident in quite a number of research activities and is crucial for rapid ARL mission-critical advancement. Many projects have impressive research in materials, processing, devices, and characterization. To continue to achieve the various goals requires a great deal of infrastructure with capital equipment renewal, as well as expansion of equipment capability. Of course some activities can be carried out using resources external to ARL or within collaborative research activities. In some cases, however, capability must reside in-house. The recent acquisition of a hydrofluoric acid (HF) vapor etching tool for microelectromechanical systems (MEMS) research is commendable. Such a capability will signifi- cantly advance and enhance all aspects of MEMS research from the point of view of time to completion for the fabrication of a device, fabrication yield, and the ability to create devices yet to be conceived. Acknowledging the absence of a dedicated equipment budget, the SEDD management team clearly tries to support the equipment needs of the researchers, even in times of reduced overall budgets. SEDD evaluates its programs and modifies its focus from year to year as necessary to meet the Armyâs needs. Thus there have been various changes to the directorateâs programs over the past 2 years since the previous ARLTAB report as the directorateâs efforts were refocused. SEDD has initiated new programs in microsystems, radar biometrics, situational awareness, compact radar, and power sources for unattended ground sensors. In parallel SEDD has intensified its focus on solid-state lasers, vision protection, sensor fusion, flexible displays, bio-inspired materials, antennas, and reserve batteries. SEDD has decreased its investments in magnetics, power MEMS, liquid reserve batteries, and platform RF sensors. The folding of ARO into ARL appears to be going smoothly. There is a very good connection between the ARO and ARL missions. ARO provides an important liaison role between ARL in-house research and external university research. Universities are made aware of the immediate needs of the Army, and in turn ARL has a natural pathway to make use of the university research results. Undoubt- edly there are organization-level efficiencies as well. The synergistic connection of SEDD and ARO was described and is clearly extremely important. Clear communication channels exist between program managers at ARO and all levels of personnel at SEDD. Research needs of ARL activities, once identi- fied and defined, are articulated to ARO to establish research programs with opportunities for contribu- tion by external entities, both academic and industrial. Furthermore, SEDD scientists are welcome to participate in certain ARO-funded programs if desired. Students are funded through ARO fellowships to have internships within ARL. Some ARO program activities, such as the Strategic Technology Initia- tives, are chaired by a program manager from ARO in conjunction with an ARL scientist. Activities are âNational Research Council, 2005-2006 Assessment of the Army Research Laboratory, Washington, D.C.: The National Academies Press, 2007.
SENSORS AND ELECTRON DEVICES DIRECTORATE 41 conducted by ARO program managers and others across the many government services to determine types of programs needed, as well as to define research thrusts. Clearly the close interaction of ARO with SEDD enables SEDD funds and research to be heavily leveraged. ACCOMPLISHMENTS AND ADVANCEMENTS Electro-Optics and Photonics SEDDâs work on electrooptic sensors has made significant progress over the past 2 years in several important areas. The infrared detector program continues to carry out excellent research and has dem- onstrated year after year very impressive accomplishments. The overall goal is to demonstrate advanced cooled and uncooled infrared (IR) detectors and detector arrays for the Army, exploiting a fundamental understanding of the physics and chemistry of various semiconductor compounds. The breadth of ARL work on materials and devices for IR detection is comprehensive. This is perhaps the only laboratory in the world with the capability and collaborations to realize devices with opera- tions that span the wavelengths across the entire infrared spectrum. The work presented covered various materials systems and devices including the following: II-VI materials HgCdTe IR focal plane arrays on silicon (Si) and high-operating-temperature long-wavelength infrared (LWIR) HgCdTe detectors; III-V materials such as AlGaAs/GaAs quantum-well infrared photodetectors (QWIPs); Type II GaSb/InAs detectors and dilute nitride GaInSbN detectors; and IV-VI materials such as PbSnSeTe detectors. The breadth and quality of the work reported are impressive. ARL is clearly a leader for infrared detector technology. The work on HgCdTe on Si, corrugated quantum-well infrared photodetectors (C-QWIPs), GaInSbN, and PbSnSeTe on Si are setting the trends. On the C-QWIPs, the image dem- onstrated with the detector array is striking with a temperature resolution less than 0.022 K. The work demonstrated clearly is moving to satisfy Army needs. SEDD has published two journal papers and three conference papers. Considering the impressiveness of the work presented at the review, more papers should be expected on the work. The use of dilute nitrides for very long wavelength infrared (VLWIR) detectors is a novel approach for extending the band gap of III-antimonide semiconductors into the LWIR and VLWIR regimes by substituting nitrogen for (a small fraction of) the antimony anions. It is a relatively new high-risk/high- payoff exploratory effort that has the potential to yield important materials results. The probability of deriving fundamental insights from this work could be enhanced through strengthened theoretical sup- port in the areas of electronic structure, growth kinetics, and disorder. A new emphasis was described that takes advantage of the antimony material system alloyed with a small percentage of nitrogen. The material system is completely unexplored and represents a first effort conducted with ARL resources; the ideas and first results are very encouraging. The work in dilute nitrides is new but very promising. GaSb-based materials such as GaInSbN with 1 to 4 percent GaN have the potential for providing a new infrared material system. The idea of integrating electronics and detectors is a good approach based on excellent materials work that continues to improve over time. The MgCdTe and HgCdTe on Si work is doing very well, with impressive results. The identifying factor of ARL work is the pursuit of the growth of HgCdTe on Si for lower-cost detector applications. SEDD has achieved up to 1 K Ã 1 K LWIR HgCdTe on Si. SEDD has demonstrated novel C-QWIP devices that have high quantum efficiencies (QE) of approximately 40 percent, which is the highest in the world. The work on Type II GaSb/InAs superlattice is progressing, with challenges on defect issues and passivation technologies. Notwithstanding these issues, devices with approximately 40 percent QE have been obtained. The dilute nitride work is now at the stage of material growth, with focus on how to
42 2007â2008 assessment of the army research laboratory reduce defect densities, improve crystal quality, and control background impurities. SEDD has achieved the highest incorporated nitrogen to date. On the IV-VI materials, SEDD is the only group in the world working on the growth of PbSnSeTe on Si. SEDD has reported the lowest defect density ever achieved in this material. SEDD has received funding from the Defense Advanced Research Projects Agency (DARPA) and other customers for the detector work. It has leveraged the expertise of various partners, including national laboratories (e.g., the Naval Research Laboratory and the National Aeronautics and Space Administration), universities (e.g., the Massachusetts Institute of Technology, Lehigh University, and the University of Illinois at Chicago), and industries (e.g., BAE Systems, Teledyne Technologies, and Raytheon). SEDD is involved in five Cooperative Research and Development Agreements, joint Army Technology Objectives, and CTAs. Work on III-nitride materials is directed toward ultraviolet device applications in the wavelength range less than the cutoff wavelength of GaN. SEDD has state-of-the-art experimental facilities in this area, and very interesting data have been obtained. However, the potential for significant new insights into these materials appears to be hampered by limited theoretical support in the analysis of the results. Outside collaboration is not likely to be an adequate substitute for critical in-house discussion and analysis. SEDD has been producing high-quality AlGaInN materials using molecular-beam epitaxy (MBE) and will be capable of growing this material using a new metal-organic chemical vapor deposition (MOCVD) system. Combining the MOCVD system with the MBE system, SEDD is able to produce various materials that can be utilized for optoelectronics and electronic devices such as high electron mobility transistors (HEMTs). From materials, to processing and fabrication, to packaging and char- acterization, SEDD is able to perform all of these functions in-house. This is important in being able to achieve its mission of fulfilling Army needs. SEDD has grown and fabricated AlGaN/GaN/InGaN light-emitting diodes (LEDs) operating at 340 nm and 280 nm wavelengths. The goal is to realize high power density emission from these LEDs. Some of the applications for these devices are water puri- fication, biological agent detection, and non-line-of-sight communications. Avalanche photodiodes in both GaN and AlGaN materials have been fabricated for use in the visible-blind and solar-blind regions respectively. There are incipient activities toward the realization of lasers using nonpolar nitrides. For the LEDs, there were collaborations with the Palo Alto Research Center (PARC) on the MOCVD growth of III-nitride materials. This technology will now be transferred from PARC to ARL for use on the new MOCVD system. There are many laboratories and centers worldwide investigating GaN devices and materials. SEDD is leading in the growth of nanoscale-compositional-inhomogenous (NCI) AlGaN materials with enhanced luminescence. The enhancement is due to localized high carrier density in the spatially nonuniform AlGaN. SEDD is also leading in the optical characterization of AlGaInN materials; this is a unique competency that is sought by outside collaborators. SEDD has received funding from DARPA, the Homeland Security Advanced Research Projects Agency (HSARPA), the Defense Threat Reduction Agency (DTRA), and other agencies. It has also leveraged the technical competencies of many collabora- tors, including Lehigh University; the University of California, Santa Barbara; and the Georgia Institute of Technology, along with industries such as Crystal IS and PARC. There is an ongoing collaboration with GE Global Research on ZnO. The investigations reported are among the best in the field and involve excellent staff. SEDD is working in a highly competitive area, and it has been able to maintain its prominence as a laboratory owing to excellence in personnel. As stated above, there are two clear areasâgrowth of NCI AlGaN and high-speed optical characterizationâwhere SEDD leads the compe- tition. The personnel in this group should collaborate closely with the RF group; the characterization technologies developed here will provide insights into HEMT materials and properties.
SENSORS AND ELECTRON DEVICES DIRECTORATE 43 The Flexible Display Center (FDC) at Arizona State University (ASU) is a unique, first-rate program that complements what the others are doing in this area. The FDC encompasses research and development (R&D) and a pilot line for a key enabling technology for network-centric operations. The present focus is on silicon thin-film transistor technology for the display backplane, with the option of transitioning to organic field-effect transistors at a later date. The principal goal of the silicon work is to develop a process that employs only temperatures sufficiently low to be compatible with flexible substrates. The purpose of the FDC at ASU was made clear, and the advantages and issues were clearly articulated. The model for the industrial partnership, complemented by academic contributions, is an interesting new model of collaboration within the United States. The ARL-defined objectives were described and c Â ertainly will be extremely beneficial to the Army mission. It seems quite clear that the needs of the Army are defined and shared with the FDC personnel, and, it is hoped, with industrial partners (although this was not clearly explained by SEDD). A question that remains addresses the manner in which the ARL or Army needs are ultimately met, such as the need for robustness in extreme environments, lightweight displays, and appropriately low-power-consuming displays. Industrial partners include process equip- ment manufacturers in addition to the key materials and display corporations. The Organic Light Emitting Diode group is attacking appropriate problems, generating intellectual property, and establishing a solid publication record. SEDD is strong in this area, and the work should be commended. The demonstration at the laboratory that works on organic materials for devices and displays highlighted the capability of the SEDD activity to include novel materials synthesis, materials deposition, device fabrication, and display manufacturing (on a research scale). The emphasis is currently focused on creating an efficient blue organic emitter, because this is technologically the limitation for full-color red-green-blue displays. A quantum chemist would perhaps be a valuable addition either to internal ARL staff or externally for collaboration on the project. The researchers are very enthusiastic with regard to discussing the research objectives and research accomplishments, and the laboratory demonstration was a success. SEDD is working with the Institute for Collaborative Biotechnologies at the University of ÂCalifornia, Santa Barbara, to develop microfluidics for the detection of anthrax, viruses, and other agents. This university collaboration appears to be working well, and the investigators appear particularly good at combing different techniques. The fundamental technology has very good potential for enhanced medi- cal care. An E-DNA compact biosensor for chemical and biological detection was presented, with the goal of making a simple, multiple-use sensor platform for several different types of biological and/or environmental threats. The idea is to have a disposable chip that just plugs in to the personal digital assistant (PDA)-like platform. Deoxyribonucleic acid (DNA) is first separated electrophoretically on a small scale using microfluidics. The challenge is loss of material due to the small size of the DNA, which results in false negatives (noise); that is why there is a focus on doing the microfluidics well. Polymerase chain reaction is used as an effective amplifier of DNA, with the results being interrogated on a gold electrode. There are several electrodes on the chip, each with a different DNA type, and they are sequentially connected to the ground electrode. The SEDD work is different from other work in that this is an all-electronic sensor, made possible by microfluidics that are electronically controlled (no exterior valves, pumps, and so on). The electronics consumes around 1 W, mostly consumed by heaters. It is to the Boardâs knowledge a smaller platform than any other for this type of application. Corrugated Quantum-Well Infrared Photodetectors SEDD is the leader in corrugated quantum-well infrared photodetector technology. The concept is brilliantly simple. The key technologist in this area is known internationally for his success in designing
44 2007â2008 assessment of the army research laboratory and building multicolor infrared detectors. The results are world-class, with a 0.02 K resolution. This is a very remarkable effort which demonstrates that a great deal of persistence can turn a promising idea into a competitive technology. The leader of this effort has been involved with QWIPs from the very beginning, and the current work on C-QWIP focal plane arrays appears to have yielded an approach that is competitive with HgCdTe focal planes in performance and will have significant advantages in cost. The C-QWIP research being performed in SEDD represents R&D at its best. The pertinence of the C-QWIP work to Army needs further enhances the importance of this research. In this hierarchy it is recognized that HgCdTe sensors offer the best performance in terms of sensitivity and quantum efficiency but require cryogenic cooling and are extremely difficult to fabricate. Bolometers are lower cost and lack the sensitivity of HgCdTe sensors but operate at room temperature (using thermo- electric coolers for stabilization). They are ubiquitous on the battlefield, being used as thermal weapon sights on guns and driverâs vision enhancements on vehicles. The promise of QWIP sensors (which also require cryogenic cooling) is enhanced performance over bolometer sensors, with substantially lower cost than that for HgCdTe sensors. These QWIPS with enhanced performance would satisfy a number of Army missions, such as large-area persistent surveillance. QWIPs can achieve a much higher pixel count (needed for wide-area surveillance) than bolometers, at a lower cost than that for HgCdTe. However, QWIP sensors, until SEDDâs recent work, had a very low quantum efficiency and could never reach their potential as a practical device for an Army application. The QWIP quantum efficiency was approximately 3 percent as compared to approximately 85 percent for HgCdTe. The reason for this is the conventional technique of coupling IR radiation into the QWIP layered structure. A reflec- tive grating is used that does not efficiently couple the IR radiation into the QWIP active layer. The grating also forces narrowband detection as compared to the wide-bandwidth detection of bolometers and HgCdTe, which further lowers the quantum efficiency. To raise the IR absorption and the quantum efficiency, the pixel size is increased, which limits the sensor resolution. SEDD invented a new con- cept for coupling the IR radiation into the QWIP active layer; it entails placing an inverted V-shaped reflector around each pixel so that the IR energy is coupled directly along the QWIP active layer. This optimizes the quantum efficiency. The assemblage of V-shaped structures gives rise to the name cor- rugated QWIP, or C-QWIP. The resulting improvements are extremely impressive, with an increase in QE from 5 percent to approximately 35 percent with broadband coupling from 6 to 12 microns. SEDD has fabricated QWIPs focal plane arrays with 2048 Ã 2048 pixels and demonstrated lower-cost cameras with a 1024 Ã 1024 resolution. This is a stunning success and has brought QWIPs back into serious consideration for Army applica- tions such as large-area persistent surveillance and helicopter piloting. The most dramatic improvement is the increase in quantum efficiency by over a factor of seven. The corrugated technique also permitted smaller pitch sizes and larger pixel-count arrays. Equally impressive with these improvements is the extensive theoretical modeling used by SEDD to support these advances. Often a clever idea like this is implemented without the supporting theoretical analysis. In these cases, while a major improvement can be demonstrated, it can never be fully exploited using a trial-by-trial approach. SEDD, however, has developed a series of integrated models to fully explain the C-QWIP performance. Some of the more important include a wavefunction model of the lattice to predict the molecular absorption spectrum, an electromagnetic field simulation of the IR coupling to the active layers, and a reflectivity optimization model including the effects of surface plasmons at the Au interface. The combination of the breakthrough corrugated concept, extensive and comprehensive modeling, and outstanding experimental results defines this work as among the best in its field. Indeed no other group has equaled this performance. This work should receive the highest level of support from ARL. It is being deployed with other government agencies. It would behoove SEDD to consider the next focal
SENSORS AND ELECTRON DEVICES DIRECTORATE 45 plane development to be 1920 Ã 1080 resolution, to take full advantage of the commercial high-Âdefinition television equipment including digital video recorders and displays. SEDDâs C-QWIP work is so good that perhaps it should be considered a national asset. This is, of course, an endorsement of the ARL concept underlying its semiconductor fabrication facility: âBuild it and they will come.â Certainly, having such a fabrication facility at ARL acts as a magnet for Âresearchers, and the Army benefits from the resultant outstanding work. It would be expensive to technically transfer the C-QWIP process and fabrication technique to any of the few remaining GaAs fabrication facilities left in the United States. If legal considerations permit, ARL management should consider an arrangement that would allow the fabrication of C-QWIP arrays at ARL to be purchased by camera manufacturers such as FLIR, DRS Technologies, BAE Systems, Insight, and others. Power and Energy SEDD is doing an excellent job of framing the research questions that need to be answered for high- energy batteries. The team is well respected and is doing high-quality work. The right scientific and technical issues with respect to a technical objective for the mission are being posed. Portable power is critical to soldiers, vehicles, and sensor applications, and SEDDâs program is on target in terms of identifying key scientific and technical challenges for Army-specific battery needs. Although lithium (Li)-ion batteries are available commercially, the specific needs of the military are often different from those of the consumer market, and for this reason it is important to maintain a significant technical effort in this area. SEDD has a strong program in battery technology, reflected in the competence of the staff and the quality of their work. The Li-ion and other battery-related work done at ARL compares favor- ably to similar work being conducted externally. The battery field and that of Li-ion in particular are fairly crowded due to commercial success with batteries. However, this is a technology that is almost exclusively produced by Asian companies and thus warrants a U.S. research presence. Batteries used by the military often have environmental and safety considerations that are significantly different from those for consumer batteries. This is reflected by ARLâs work in low- and high-temperature electrolytes, as well as by the safety testing of battery packs of different cell chemistry punctured by ammunition rounds. The SEDD effort is well respected in the field, and it is anticipated that the quality of work will continue in this vein. In the Li-ion field some degree of collaboration with a manufacturer is usu- ally necessary in order to gauge the value of internally developed technology. This is so because the charge/discharge cycle life and/or safety of the system is invariably affected by any changes in the cell chemistry, and academic laboratories are not equipped to produce prototype batteries that can reliably test such parameters. The work of SEDD in electrolytes and cathode chemistry is of a high caliber and may lead to improvements in Li-ion chemistry aligned with military needs. Isotope batteries for embedded sensors comprise an area of interesting work that is important to the Army. The concept here is to meet the need for batteries with extremely long life in isolated locations through the technology of isotope batteries. The underlying idea of collecting the charge emitted by radiation has been communicated through basic undergraduate instruction in modern physics and through the public mediaâs treatment of NASAâs use of the technology. The nuclear fission industry has done extensive and detailed research on this topic for more than six decades. NASA and the Idaho National Laboratory have the technology well calibratedâhaving, for example, complete charts of which isotope material to use for what duration of battery life. Batteries with a long shelf life and batteries with a long operating life are definitely a need for the Army. The needs are unique enough to justify doing research in a number of technologies. One type is isotope batteries; another is thermal batteries. There are com- mercial batteries currently in use in the public utility industry that approach a 20-year life. SEDD is
46 2007â2008 assessment of the army research laboratory doing important work and is enthusiastic about it. Beta-particle batteries are unlikely to be manufactured commercially because of the liability associated with radioactive sources. Applications definitely exist and will probably proliferate further. Maintaining some expertise in this area is necessary. SEDD is alone in the world in building SiC thyristors with pulse power capability. SiC is a very promising technology in which SEDD is on the leading edge. SEDD has been conducting research on SiC applications and issues for quite awhile, and the investment has given it a significant advantage in bringing this technology to the soldier early. ARL employed the now commercially available SiC diode at a very early date. In the case of the metal-oxide-semiconductor field-effect transistor (MOSFET), there is great commercial interest and potential. Industry is very interested in the SiC MOSFET and will track its development closely. SiC thyristors are a niche product. They form the switching element of the electromagnetic (EM) armor and the rail gun. No other semiconductor component can handle the current pulses anticipated in such applications. Thyristors in general are considered a niche technology, being obsolete for most applications and existing primarily in legacy equipment and certain niche applications. A good example of a niche outside ARL is high-energy physics research. SiC has taken much longer to develop than expected for a semiconductor technology, much to the disappointment of its proponents. However, SiC has a great deal of promise for providing exceedingly lighter, faster, more powerful, and more capable power supplies and high power equipment. Thus SEDDâs investment and leadership role will pay off handsomely as the technology continues to develop. Persistence and patience will be required to maintain SEDDâs primacy, as breakthroughs and useful developments, though yielding high payoff, will continue to be difficult to achieve and will likely to continue to arrive all too slowly. Very good work in this area is published and presented by SEDD at conferences. The specific application at hand is a leading-edge conceptâusing the SiC (and Si) gate turn-off thyristor (GTO) as a means of accelerating switching recovery time. Thyristors are notoriously slow to regain their ability to block voltage after commutation. By actively removing charge from the gate region, a useful capability of the GTO, recovery time is halved in the experiments that were shown. The demonstration was very well done. The conducting of the test seemed good, including discharge source, instrumentation, interruption of current, and high-voltage restore at the end to verify recovery voltage. This is reminiscent of synthetic testing used for high-voltage circuit breakers by industry leaders. This experimental validation is a significant development. It is applicable to semiconductor-based protection on high-voltage circuitry as well as to the EM armor and rail gun applications that were shown. Using the GTO, a technology that the Japanese have led in development for 25 years, represents an excel- lent capture of foreign technology for a U.S. application. Close collaboration with U.S. manufacturers made this happen. Such developments are encouraging, showing a significant advance that only one in a leading position could identify and exploit. Determining appropriate data on reliability is going to be necessary as SiC devices become more available and begin to appear in Army hardware. ARL lacks the resources to do this as it needs to be doneâit is just too expensive. However, ARLâs partnership with the major domestic manufacturers and its leading research position should encourage the manufacturers to be aggressive in getting data on reliability. Nanocrystalline magnetic materials for direct current (DC)-DC power conversion is a key technol- ogy for hybrid electric vehicles and pulse power. These devices must be bidirectional, and for military vehicles they typically convert between 300 volt DC batteries and a 600 volt DC bus. These need to be efficient and, most importantly, need high power density (kilowatts per liter) (to a lesser extent high s Â pecific power [kilowatts per kilogram]). A second key design constraint is heat removal, which is par- ticularly challenging in vehicle applications, which involve high power and severe volume constraints. The group at SEDD has established a working relationship with Carnegie Mellon University, the University of South Florida, and Magnetics, Inc., to develop high power density devices. A demonstra-
SENSORS AND ELECTRON DEVICES DIRECTORATE 47 tion focused on inductor materials that are used in DC/DC converters. The hardware was an inductor mounted on a cold plate with liquid cooling. Thermal images (IR camera) provided a map of the core and winding during operation. These magnetic materials need to allow high magnetic saturation fluxes and low power losses at the desired frequency. Iron-based materials from Magnetics, Inc., were used. These materials are coated with polymers to reduce eddy currents and are particularly suited for high frequencies. The target application is the Future Combat Systems (FCS), and there is collaboration with the U.S. Army Tank and Automotive Research, Development, and Engineering Center (TARDEC) on hybrid electric vehicle design. Goals have been established (6 to 8 kW/l), and progress toward these goals is evident. Unquestion- ably, this technology is important for the FCS. The research at SEDD is excellentâof high quality and relevant. At the same time, many others throughout the world are developing similar technology for automobiles and buses. It is likely that the heavy-duty vehicles of interest to the Department of Defense (DoD) require higher power density than is needed by commercial light vehicles, but close attention to developments in the commercial (particularly overseas) sector are warranted. SEDD used U.S. industry to overcome the technical problem at hand and used a U.S. university for the advantage of its advanced knowledge and experienceâa superb model for progress. This is but one in a sequence of such advances that must be made to bring hybrid electric vehicle technology to Army vehicles. The demonstration of advanced nanocrystalline magnetics was performed well. Appropriate issues of heat generation and heat sinking and how they were incorporated into an effective and innovative design were illustrated quite capably. The next step, already begun at SEDD, is to develop and apply high-energy capacitive storage. U.S. industry has an interest and some investment in ultracapacitor storage. The automobile companies will bring it into their products in the next few years, but the automobile companies will not take it far enough, because Army vehicles have a need for more power and energy than are required for commercial automobiles and light trucks. When the automobile companies have confidence in the technology, they will send it to universities, such as the University of Wisconsin and Virginia Polytechnic Institute and State University, for validation, as they have done with magnetics already. Advances will also appear in Europe and Japan; SEDD has shown the capability to capture such advances in electric power and energy from non-U.S. sources. SEDD is at the leading edge of nanocrystalline magnetics; it needs to catch up a bit in energy storage. There will be other technology issues in power and energy applied to Army vehicles. SEDD has a good model for success that will serve it well. These are high-payoff activities, and SEDD has shown the ability and engaged the people appropriate for doing a good job of following through with them. Radio Frequency and Electronics SEDD has a vision for advanced radio-frequency technologies that includes multifunction RF systems for future battlefield platforms to enhance lethality, survivability, and mobility. To implement this vision, the directorate is focusing on antennas and RF front ends, nanoelectronics and MEMS, RF sensors, prognostics and diagnostics, and RF-directed energy. In order to improve antenna designs, in situ antenna modeling is being used to analyze antennas in the environment in which they will be used. SEDD is using rapid prototyping and fabrication, together with modeling and high-fidelity measurements, to design and demonstrate integrated antennas for Army applications. Examples shown were helmet-mounted antennas, in situ antennas for ground vehicles and unmanned aerial vehicles, lapel-mounted RF identification tags, and antennas designed to be worn by the soldier.
48 2007â2008 assessment of the army research laboratory Antenna modeling for so many different applications is an extremely difficult problem, and it is use- ful to have multiple types of code centralized in one laboratory with people who are experts in knowing what type of numerical method to use for different situations. This effort includes numerical EM for antennas, which is a well-established and very heavily researched field. Well-known commercial codes are used, which is entirely appropriate. It was not clear how the choice of tool is made and why in some cases one tool might be better than another. Experienced researchers in this field of numerical EM for antennas tend to use their favorite code or method, mostly because they have it or they know how to use it. It would be a worthwhile effort to develop a methodology for what code to use for optimal antenna design in specific situations: real ground, finite ground, complex dielectric bodies, small bandwidth, broadband, single polarization, and others. An interesting matrix could be created that would be quite useful to antenna designers. There are some relatively recent research papers that would be of interest to SEDD, although there are no commercial codes using the techniques described. For example, recently the IEEE Microwave Theory and Techniques Societyâs Microwave Prize was awarded to a numerical EM paper which showed that finite element modeling (FEM) can be done with large-domain elements very efficiently. Such a method might be well suited to the problems that the Army is faced with. SEDD is proposing that rather than develop new numerical methods in an already crowded field, it is better to develop the know-how related to the design of antennas in complicated environments. Antenna modeling and simulation is a research project that can provide great benefit to the Army and can lead to improved front ends. If a more general analysis method were established by SEDD, the conclusions would be of interest to people in the field who do not wish to make numerical EM their expertise but need to know how to improve antenna designs. The SEDD group has excellent expertise in antenna design. Improving the approach over time to move from discrete antenna solutions to a more general systematic approach as a final goal would provide great benefit to the community at large. Millimeter-Wave Imaging SEDD is developing advanced technology for millimeter-wave (MMW) imaging. This approach offers solutions to imaging in adverse conditions where other imagers are impaired, such as when look- ing through dust for helicopter landing under brownout conditions, looking through fog and smoke, and for other applications such as concealed-weapons detection. SEDD has a clear objective of increasing resolution while decreasing size, weight, and cost. It also has a good transition plan through the Armyâs Communications-Electronics Research, Development, and Engineering Center (CERDEC) and its Avia- tion and Missile Research, Development, and Engineering Center (AMRDEC). SEDD has made excellent progress, with significant accomplishments that extend the state of the art in MMW imaging. These accomplishments include extending depth of field using cubic phase elements; demonstrating broadband antireflection gratings and three-dimensional rotating beams for ranging; and measuring attenuation effects in high-density dust clouds. SEDDâs approach consists of using a low-cost focal plane array with MMW lenses, which enables the demonstration of flat-panel MMW imaging. Combined with a novel antireflection grating and rigorous EM modeling and computation imaging, this approach may enable the next generation of MMW imagers that can be used in the field. SEDD is at or beyond the current state of the art for this technology. It is effectively leveraging the directorateâs well- known expertise in microwave and millimeter-wave technology in a new area that holds great promise for meeting immediate Army needs. An interesting extension of this project would be to evaluate the possibility of integrating MMW imaging with IR imaging to provide a display that incorporates both. SEDD has the expertise for both
SENSORS AND ELECTRON DEVICES DIRECTORATE 49 types of imaging systems. An integrated display using infrared detectors, such as the QWIP discussed earlier, and MMW detectors could provide an imaging system with performance that far exceeds that of any other system currently available. Microelectromechanical Systems The Microelectromechanical Systems Technology for MicroRobotics group has done an outstanding job, especially given the relatively low level of internal investment. The group has obtained DARPA financing for the piezoMEMS and nanomechanics work, and it has a well-planned top-level roadmap for FY 2005-FY 2010. It is competitive with its peers in the nanoscale technology area, and the group members are excited and energized regarding the potential for this new field. The overarching vision presented for microsystems was that of a scorpion-like, bio-inspired, biomimetic mobile sensor platform in the centimeter size range. Although this vision is extremely aggressive, the SEDD research teams have organized a comprehensive and complete set of research projects that have a strong likelihood of posi- tive research results. Certainly, should such a device be made to work, it would be a disruptive sensing technology in much the same way that the mobile antitank mine developed under a DARPA program was disruptive to mine-clearing capabilities of the enemy. The ARL team has not yet thought through all the scenarios for the use of such disruptive mobile sensor platforms. However, it has taken the approach of making an aggressively early demonstration of subcomponents of the system, in particular a totally functioning, insect-scale, piezoelectric-actuator walking leg. Although the issue of supplying onboard power will be problematic, the SEDD team has done a thorough job of evaluating and minimizing the total power required. Encouraged by the DARPA Microsystems Technology Office, the SEDD team is developing the materials that may be used to sell a program of this sort to DARPA management and provide funding not only for ARL but for others in the field. These activities are strong indications that ARL is pursuing the right scientific and technical issues for microsystems applied to miniature mobile sensor platforms. The ARL program for microsystems is conducted by a SEDD team that understands the underlying science and comprehends other, comparable work done in the field. There is not, to the Boardâs knowl- edge, any such program in any other part of the Army. The SEDD team is fully leveraging DARPA initia- tives in the field and is exploiting all the expertise in lead zirconium titanate (PZT) piezoelectric actuator thin-film deposition in the Army. The team is aware of the microsystems (miniature robot) work at major universities such as the University of California, Berkeley; the Massachusetts Institute of Technology; Stanford University; and the University of Michigan. The SEDD team is leveraging its connections to others in the field for access to the necessary fabrication tools not available in ARL. Its acquiring of its own hydrofluoric vapor etch machine, which has increased yield and increased fabrication progress immensely in the past year, is commendable, as is the addition of the advanced HF etching system for MEMS fabrication. The shortened cycle times and improved yields will benefit all MEMS activities. The work presented by the SEDD team in microsystems is at the state of the artâin particular, its efforts in micro- and nanoenergetics, microrobotics, and microswitching of RF. Its work on PZT, three- dimensional circuit elements, piezoelectric actuators, and microrobotic components is leading the field. The teamâs work on micro shock sensors, micro fatigue testing, and micro energy harvesting is near to, but slightly behind, the state of the art. Since much of the work that is at the state of the art is relatively new, it is understandable that the number of publications is still lower than desirable. However, there is a strong effort to develop patents (several in PZT and PZT actuators are in process), and the group of predominantly young engineers seems highly motivated to publish. Overall, the group seems strong, competitive, energetic, enthusiastic, and diligent, though recently formed and including young members.
50 2007â2008 assessment of the army research laboratory It is performing well for its size and newness. It will be increasingly important for the microsystems team to continue maturing and to increase the rate of publication. The program focuses on microsystems that are bio-inspired and is capitalizing on their in-house strength in actuation and MEMS activities. Attention to overall objectives is driving the application of system analysis to all endeavors, and issues related to ground mobility, motor and behavior control, and power subsystems are considered together to advance a demonstration in the near term. The near- term goal of demonstrating a robot is challenging, but it will certainly be instrumental in forcing all technological thrusts to contribute necessary project-directed components. The system design focus has advanced to consider power consumption as a function of time by looking at off-the-shelf technology in the near term, with attention to research-driven and advanced technology toward the longer-term goal of partial operation. It seems clear that the demonstration and bio-inspired robot project will lead to fundamental advances in microelectromechanical and nanoelectromechanical systems (MEMS and NEMS). It is important that the overall system approach be applied to push forward the technology and research directions. The funding from DARPA is important to leverage the ARL monies dedicated to this task. Furthermore, the opportunity to use the leading-edge technology held at ARL in piezoMEMS is a great advantage for propelling the project forward rapidly. One point to note is the current movement to remove all lead from integrated circuits because of environmental concerns; the impact of such restrictions should be considered as the piezoMEMS technology is employed. The MEMS work within SEDD on using such devices to improve the thermal coupling of power electronics is very good. It represents a novel technique for increasing thermal coupling beyond tradi- tional indium soldering to heat sinks or microchannel coolers. For example, although indium-soldered microchannel coolers have been used for high-power laser diodes, the use of MEMS and MEMS bond- ing techniques offers several significant benefits in mounting laser diodes to a heat sink. The thermal resistance from the laser diode to the heat sink will be reduced and more repeatable, thereby allowing the operational temperature of the laser diodes to be reduced and more controllable. With lower and more controlled operational temperatures, the laser diodes are much less prone to premature failure (i.e., reliability problems). Alternatively, with the higher heat fluxes possible owing to a lower thermal resistance from the laser diode to the heat sink, the output power of the laser diode can be increased. The problem of reflowing of the indium solder that is used to attach the laser diodes to the heat sink can be eliminated, thereby allowing a preeminent failure mechanism of high-power lasers to be avoided. This work has been recognized by DARPA, and the MEMS effort should continue to receive ARL support. Radar The human radar signature investigations at ARL started in 2006. The goal is to find Doppler radar signatures related to human behaviors such as walking gait, breathing, speech, carrying heavy objects, changes when nervous, and so on. Since this is a new project, there is not yet too much progress, but it is an interesting research topic. Since radio frequencies are measured that reflect changes in the move- ment of the human body, including movement of the internal organs, physicians are also contributing information to further correlate to the obtained RF data. Significant progress was made in preparing the documents to obtain permission for research on humans. Such applications are extremely long and tedious to complete, but they are certainly important and valuable. The effort appears to have clearly considered the objectives and to have created the necessary collaborations to complement the internal ARL activities.
SENSORS AND ELECTRON DEVICES DIRECTORATE 51 The large challenge will be in collecting a solid data set and then doing appropriate data process- ing. It seems that the group working on the project will need a very low phase noise local oscillator and long integration times for low Doppler shifts. For the heart muscle, velocity is 7 to 15 cm/s, which is a very low Doppler shift. The group is examining radar signatures from 200 MHz to approximately 100 GHz, but it was not clear yet what the best choice of frequency would be. Electromagnetic models and radar measurements were used to examine the polarimetric and Doppler signatures of a human body from ultrahigh frequency (UHF) through Ka-band frequency. The group is aware of work done at the University of Hawaii and by a company in the Netherlands. The human radar signature is a new project that started in 2006, with some promising initial work. ARL is aware of other work in this field, and the Board is not aware of any additional radar-related work that the SEDD group did not mention. This is a worthwhile research topic with some conclusions to be reached within a few years and seems like a constructive and appropriate research project with potentially interesting results. Ultrawideband (UWB) penetrating radar for sensing through walls uses extremely short pulses to provide accurate range resolution. It is not a new idea, but it has only recently become practical with high-speed electronics. UWB radar has the potential to image through walls and other objects with low to modest electrical conductivity. Being able to do so would provide clear military and law enforcement advantages. The short pulses associated with the wide bandwidth allow for very accurate determination of distance. Multiple sensors or synthetic aperture techniques can be used to provide imaging. ARL has experience with UWB radar. As early as 1995, ARL explored the military potential of UWB to penetrate foliage to find targets. The current work is focused on urban warfare and the technol- ogy necessary for finding personnel in buildings. This problem is different from that of the short-range UWB radar that is being pursued commercially and by the military for mine hunting. The urban warfare problem requires that meaningful images be generated by sensors operated at longer ranges than are required for most other applications and moving target indicator (MTI) capability. Under urban war- fare conditions, the processing required to generate meaningful images is complicated not only by the changes in target and clutter reflectivity over the wide signal bandwidth, but also by the low signal-to- noise ratio of the typical returned signal. To address these and other issues, the current ARL program is focused on modeling and simulation and on data collection in realistic urban scenarios. The results of these efforts are being used to help develop algorithms for synthetic aperture radar image formation and MTI techniques. This is a meaningful foundation for the development of an important military and law enforcement capability. For its potential to be realized, it needs to be coupled with a strong signal- processing effort that can take advantage of that foundation. The low-frequency UWB radar work is being done in collaboration with the Army CERDECâs Intelligence Information Warfare Directorate and the Office of Naval Research. Image Enhancement and Understanding Two image-processing projects enhance the resolution of a long-wavelength infrared uncooled imager, which allows for better missile performance or lower-cost sensors. The first project took advan- tage of the fact that the imager moved as a unit while tracking a target that retained its shape between frames. This allowed the development of algorithms that filled in missing pixels from one frame with those available in others. A computationally inexpensive way to estimate the highest frequency that should be amplified before noise dominates was developed as part of the project. A critical feature of this effort was finding an efficient approach that could be realized in tactical hardware. The work was done with real sensor data and generated excellent results.
52 2007â2008 assessment of the army research laboratory The second project was a super-resolution effort also done on real data. Super-resolution operates by amplifying the higher special frequencies in an image that are attenuated owing to system issues. One price of this process is the amplification of noise. The super-resolution and deblurring algorithms are novel but not unique. That said, every signal-processing algorithm needs to be customized to the sensor and the environment, and this project solved a real problem. What matters is the degree to which these algorithms are tuned to the application and how robustly they behave in environments that the Army cares about. For instance, does the super-resolution work if the background of the image has significant spatial frequency content? A commendable useful collaboration was established with personnel from the Night Vision Laboratory of the Human Research and Engineering Directorate (HRED), the Naval Research Laboratory, the Army AMRDEC, and the National Institute of Standards and Technology. Both efforts show an understanding of the sensors and work with real data and effective algorithms that meet the operating constraints of a military system. This is an excellent formula for success. Three papers have been published in Applied Optics since 2006. Image understanding, or machine recognition of complex images, is of critical importance to the military, because asymmetric warfare and long-range lethality require autonomous and semiautonomous processing of imagery. The challenges of processing such images involve finding a suitable representa- tion space, the development and application of models, the rejection of clutter, the use of context, the application of constraints, training, finding robust solutions, and the choice and tailoring of a Âclassifier. SEDD has begun working a new set of classifiers and applications. Recent publications include an enhanced matched filter technique in IEEE Signal Processing Letters; an eigenspace separation transform in Geoscience and Remote Sensing Letters; and a change detection method in the Journal of Applied Remote Sensing. Sensing The autonomous sensing activity at SEDD includes both sensing and data analysis. The work in acoustic sensing has a long history, and this group continues to play a leading role in the field. The results have led to fielded technology with a significant impact on Army operations. The activity in magnetic and electric field sensing is interesting, with clever engineering behind it. Regarding the âautonomousâ part of autonomous sensing: the nature of what is meant by that term is changing rapidly in the sensing and signal-processing communities. While much is still speculative, there appears to be a convergence of technologies in sensing, signal processing, robotics, and networking, leading to an envisioned system of autonomous sensors making decisions about data collection in a feedback loop based on the analy- sis of previously gathered data. ARLâs vision for autonomous sensing is not yet at this level, nor is it clear that it needs to be. The application of existing signal-processing and data fusion methodology to u Â nattended ground sensing is clearly an important area to the Army, and that work is commendable. It is recommended that there be more interaction between the autonomous sensing group and the MEMS microsystems group. The small bio-inspired device may turn out to be precisely the kind of platform appropriate for tomorrowâs highly mobile networked autonomous sensor. The work in sensor fusion and image understanding is focused primarily on adapting extant technolo- gies to Army needs, including immediate operational needs. SEDD does outstanding work in this area and has state-of-the-art capability. The aerostat approach is particularly effective. Significant work has been undertaken in applications of sensing technology to sound source detection. While it was difficult to distinguish between the research contributions of the SEDD researchers and those of the groupâs contractors, the group discussed its research in depth and professionally, and the quality of the research is quite good. One important piece of work is the acoustic propagation modeling. Other acoustics topics
SENSORS AND ELECTRON DEVICES DIRECTORATE 53 presented were infrasound and vehicle tracking. Collaboration with other in-house organizations (e.g., CISD) and outside organizations could strengthen this activity. The acoustics group continues to be active in the Military Sensing Symposia on Battlefield Acoustic and Magnetic Sensing (MSS BAMS), SPIE meetings, and publishing in the proceedings. In Novem- ber 2008, the group helped sponsor a special session at the Acoustical Society of America meeting in Miami, Florida, on acoustics for battlefield operations and homeland security. The group continues to play active roles in the Long Range Sound Symposia. In June 2008, the acoustics group participated in the International Technology Alliance NATO measurement exercise in Bourges, France, to localize impulsive battlefield sounds from military sound sources using multiple sensing platforms. The unattended ground sensors group effort is acquiring an active frequency modulated sonar unit from the Johns Hopkins University Applied Physics Laboratory that will allow ultrasonic Doppler measurements in conjunction with other sensing technologies including IR and visible technologies for the human factors research. This work should complement the similar micro-Doppler radar work for human motion that was initiated in 2008. The group should review the open literature on human- cadence-Âdetection signal processing and consider the possible incorporation of other sensing technolo- gies within the group, including the electric and magnetic field sensors and IR technologies to sense human motion behavior. The acoustics group continues to devote significant time to technologies deployable in the field in the near term. Its contributions to measurement and signature intelligence (MASINT) applications are notable, including contributions to improving the microphone performance of the unattended transient acoustic MASINT sensor (UTAMS). From an acoustical perspective, the investigative approach is analytical and interesting. Low-cost unattended sensors to monitor power-line usage, vehicle movements, and other activity demonstrated, and information was presented on electric field sensing, including information on vehicle signatures in power-line electric fields; passive, remote classification of power-line activity; and under- ground electric field sensing (resistivity imaging). The sensors in all of these applications can be very low cost and can have long lifetimes, making them suitable for extended surveillance. The realizations being pursued are applicable to important, current military needs. This work requires very sensitive measurements of low signals in the presence of much larger signals, and it needs to be done with low- cost sensors. In some cases it requires fusion with magnetic, acoustic, or seismic sensors. The work is outstanding, including field data collection, modeling, analysis, and a unique laboratory measurement capability. Collaboration with a commercial company allowed for the production of low-cost sensors, and other collaborations provided specialty skills. OPPORTUNITIES AND CHALLENGES Overall, the Sensors and Electron Devices Directorate is performing at an outstanding level in the research, development, and deployment of technologies that have both near-term and long-term benefit to the Army. The breadth of the SEDD work in IR detectors is very impressive. In some cases a critical assess- ment is perhaps necessary to determine if sufficient resources are available to pursue all of these efforts âMASINT is scientific and technical intelligence information obtained by quantitative and qualitative analysis of data (metric, angle, spatial, wavelength, time dependence, modulation, plasma, and hydromagnetic) derived from specific technical sensors for the purpose of identifying any distinctive features associated with the source, emitter, or sender and to facilitate subsequent identification and/or measurement of the same. UTAMS is an acoustic sensor system created by ARL, used to locate sources of hostile artillery and improvised explosive devices.
54 2007â2008 assessment of the army research laboratory simultaneously. Specifically, this may be an issue with the Type II superlattice work, where state-of- the-art results in the mid-wavelength infrared (MWIR) regime were achieved, but the extension into the LWIR regime appears to have made little progress. The continued examination of the Type II superlattice approach is possibly less productive and resulting in a dilution of other effort. SEDD has been responsive to feedback from the Board in this area. A well-known contribution of the SEDD acoustics group is its continued and significant presence at the MSS BAMS. The SEDD acoustics group plays the lead role in organizing this meeting and presents research papers on current SEDD acoustic research efforts. The group is also active in other meetings, including the NATO SET 107 and the SPIE annual conference in Orlando, Florida. This being said, two weaknesses of the acoustics research group are the lack of acoustic publications in refereed journals and poor or irregular attendance at professional society meetings such as those of the Acoustical Society of America (ASA). Clearly, during wartime ARLâs focus shifts from the more basic 6.1 and 6.2 research to engineering development. This was quite evident in several of the posters presented, and also evidenced at recent MSS BAMS meetings. However, for ARL to acquire and maintain its standing as a prestigious acoustics research group, acoustic research that is publishable in peer-reviewed scientific journals must be accomplished. This is not occurring now. The ARL scientists conducting acoustics research are outstanding contributors and should be encouraged to attend the professional society meetings that are closely tied to the peer-reviewed journals on a regular basis. An example is the Journal of the Acousti- cal Society of America and the ASA meetings, where there are routinely sessions on outdoor sound propagation and the coupling of airborne sounds into the ground. Such activities require recognition by ARL management that time is needed by journal authors to write and even rewrite manuscripts after the review process. Also, since HRED has the new Environment for Auditory Research facility, collaboration should be encouraged between the SEDD acoustics group and HRED. During the next assessment, it would be helpful for SEDD to further elucidate how ARL supports the other branches of the Army in terms of portable power needs, how the various branches col- laborate, or how advances in battery chemistry are transitioned from ARL to deployed products. This would enhance the Boardâs understanding of the extent to which the research program reflects a broad understanding of the underlying science and of comparable work being done within other ARL units and within the DoD, as well as in industry, academia, and other federal laboratories, and how well it employs the necessary resources with respect to instrumentation and other elements. The demand for light, compact power sources in the U.S. military is large and growing. The importance of this technology warrants a well-coordinated response in the military laboratories, and this appears to be lacking. There also needs to be some further discussion of how ARL intends to move technology from the laboratory to the Âsoldier. This is particularly true in the United States, where there is no significant manufacturing base for Li-ion chemistry. ARL management should consider strategies for formalizing specific management and reward struc- tures for crosscutting projects that encompass teams of researchers drawn from multiple directorates. There is a particular opportunity for these types of collaborations at this time, since CISD is beginning an effort in multicore processors and embedded supercomputing. These projects need effective applica- tions, and there are several SEDD projects that clearly need the computing horsepower. Together, these need to be recognized as systems projects with cross-directorate ownership. SEDD could also benefit from an expanded focus on data-analysis techniques, specifically machine learning and data-mining algorithms, and from incorporating these methods into the system designs. This can be accomplished with additional staff focused on system design and data analysis or by building collaborations with per- sonnel in the CISD. Another example would be collaboration with personnel in CISD known to have strength in signal processing.
SENSORS AND ELECTRON DEVICES DIRECTORATE 55 OVERALL TECHNICAL QUALITY OF THE WORK SEDD management is doing an outstanding job in the following areas. It has been successful in attracting new talent to the organization and retaining the best of the existing staff. SEDD management has created a dynamic environment for creative research, and staff morale seems very high. SEDD has developed a strategy to build a top-notch and in some cases unique infrastructure as a mechanism to attract outside collaborators. This is an excellent approach that seems to be working. In the long term it will be of significant benefit both to the Army and to the scientific community as a whole. A strong and commonly held culture was observed with regard to SEDDâs âowningâ science and technology on behalf of the warfighter. From a science perspective, SEDD owns the applications and actively seeks to work with the best scientists to innovate new or better solutions. The staff shows a generally impressive understanding of both the applications and the relevant science and in-depth under- standing and eagerness to provide the warfighter with an improved product. Dedicated staff is working in a very good infrastructure. Attracting and retaining the staff with the Armyâs needs as their motivation is the key deliverable for those who are stewards of ARL. On that front, SEDD is in great shape. The leadership should consider ways to increase the odds that some of the new talent added over the past 5 years will stay at ARL and will have an impact. In addition to the physical infrastructure, the âbrain trustâ needs to be kept current. There is a great mix of junior and senior staff members within SEDD. There is also access to a wide range of industry and academia. The interaction between SEDD personnel and outside collaborators in industry and academia is commendably strong, and interactions between ARO and SEDD staff should be expanded. Based on the work presented, SEDD is extremely strong in the projects that may be characterized as engineering or systems development. SEDD has demonstrated that it can make contributions that have immediate impact on current or near-future Army operations. The scientists and engineers involved in this work are highly motivated and goal-oriented. Novel device and system work, particularly the kind that requires the integration of a team of researchers spanning multiple disciplines, also is executed with much energy and enthusiasm. There appears to be a trend in SEDD to more applied research as opposed to basic research. Given the immediate demands on the Army, this is understandable, but it is hoped that the trend will be self- correcting over time so that ARL does not lose its focus on basic, 6.1-type research. SEDD does appear to have a healthy ability to change research directions over time based on Army needs, with 10 to 20 percent of its projects being redirected yearly. In the future, the Board would like to see the work that aims at fundamental materials research that supports the more applied work. A strong theoretical support base can have a significant impact on the materials research within SEDD. Theoretical work provides guidance to some of the efforts and is indispensable for thorough analysis of the data generated. The scientific quality of the research in SEDD is clearly of comparable technical quality to that executed in leading federal, university, and industrial laboratories, both nationally and internationally. This is not unique to a single area of SEDD but can be demonstrated throughout the directorate. For example, SEDD is a leader in infrared detector technology, advanced RF technologies, image processing, and power components such as SiC thyristors. The SEDD research program reflects a broad understand- ing of the underlying science, which is reflected in the overall success of the research and development programs. In general, SEDD strives to understand what other research teams are doing here in the United States as well as internationally. The qualifications of the SEDD research team are compatible with the challenges of SEDD research. SEDD is fortunate to have a leadership team that has created an environment that attracts and retains top scientific and engineering talent. The technical community recognizes the excellence of these qualifica- tions through awards and honors, such as IEEE Fellow status. Research challenges are best addressed
56 2007â2008 assessment of the army research laboratory not simply through staff credentials but through the combination of talent, motivation, and teamwork. SEDD scientists and engineers are not only talentedâthey are also highly motivated and work together in a team environment to deliver solutions to Army problems. An organization such as ARL is judged primarily on the transition of solutions from the labora- tory to the field. Thus, experimental results are usually at the forefront compared to theoretical results. SEDD does an excellent job of using computational methods to support experimental procedures, such as in signal processing or antenna design. Theoretical foundations are not necessarily given as much emphasis as computation or experimental methods. While SEDD has strength in the theory behind its research, there are some areas, as noted in the âOpportunities and Challengesâ section above, where additional support in the development of deep theoretical foundations could benefit ongoing and future programs. SEDD has well-equipped laboratories and facilities to support its ongoing projects and is responsive to the facilities needs of its researchers. As an example, the recent acquisition of new etching tools for MEMS fabrication has enhanced the production of these devices. That being said, acquiring the capital investment necessary for state-of-the-art research is an ongoing battle, especially given current and future funding constraints. The facilities and equipment available to SEDD determine in part whether the appropriate human resources will be available to achieve future success. Top-notch scientists and engineers are attracted to organizations that provide not only interesting projects but also the capital investment necessary to achieve the goals of those projects. To this end SEDD will require the support of ARL management to ensure that it has the investment resources necessary to keep SEDD at the forefront of research activities worldwide. SEDD management and SEDD researchers have been extremely responsive to the Boardâs recom- mendations. The technical assessment process takes time and resources in order to prepare, present, and discuss reviewed programs and projects. SEDD has taken a proactive and positive approach to the assessment process, which in the Boardâs perception has become beneficial to all involved.