Materials Research to Meet 21st-Century Defense Needs (2003) / Chapter Skim
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5 Electronic and Photonic Materials
5 Electronic and Photonic Materials
Pages 95-134
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. The tremendous vitality and innovation of the private sector allowed the panel to consider which future defense needs could be met by making use of commercial developments in industry and which were so specific to DoD as to require DoD investment.
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Progress in electronic and photonic materials and systems that are heavily dependent on them, such as Microsystems and sensors, is occurring at an astonishing rate, fueled in large measure by tremendous investments by the private sector. This panel considered which future defense needs could be met by taking advantage of commercial developments and which were so specific to DoD as to require DoD investment.
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need to mount operations in a wide variety of conditions, requires increased reliance on systems that can detect, identify, defend against, or avoid many types of threats. Because such systems must be deployed on military equipment, as distributed sensors, or on individual soldiers, they must be compact, light, energyefficient systems with broad capabi I ities.
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Monitoring of personnel for health or exposure to chemical or biological agents will become increasingly important. Monitoring the health of equipment in the field is also a longstanding need, as already detailed in Chapter 3.
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Since many future military systems will be space based, use lighter platforms, or be deployed on individual soldiers, these demands are becoming imperatives. Significant improvement over existing capabilities can be achieved only by inserting novel high-performance electronic materials into sensors, detectors, and components.
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High-power electronic components; Analog/digital converters; Electronic beam steering; Radio frequency (RF) microsystem components; · Acoustic components; and Ferroelectric materials.
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Materials for low-frequency and high-power applications like SiC and its derivatives are promising, but achieving the required signal purity must be rooted in a fundamental understanding of how to control their chemistry, crystal growth, epitaxy, and defect density.2 The group III-nitride materials are also promising, but meeting the operating requirements for high-power applications or in hostile ambients will require interconnects and overlayers that can function around 500°C. In addition to detailed understanding of crystal growth and the control of important defects in the materials, attention must be paid to high-temperature contact materials, overlayers, and joining materials.
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Electronic Beam Steering One of the biggest challenges facing defensive systems is replacement of the mechanical or optical (mirror) beam steering with al l-electron ic laser-beam steer)
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The military will continue to have an insatiable appetite for data storage. The sorts of materials issues that arise in pushing storage density 103
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Materials Processing Optimizing the performance of existing materials and successfully fabricating new ones with extreme properties will succeed or fail in large measure with the emphasis given first to understanding and then to controlling their fabrication and processing. As an example, improved materials and processing will enable production of components and subsystems (Figure 5-2)
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Materials for Revolutionary Technologies The scaling of both Si planar CMOS technology and high-density storage using known approaches will reach fundamental limits within the next 15 years. Perhaps the most fruitful area in which to look for potentially revolutionary technologies is in materials and material architectures that would enable entirely new approaches to computation, encryption, and data storage.
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DoD investments should emphasize electronic materials for systems to identify, locate, and engage or defend against threats; for compact systems to transmit very high power at very high frequencies; and for embedded technologies that enable these systems. Materials research investments that are most likely to pay dividends are fundamental studies to increase understanding of existing materials; development of new materials with extreme properties; materials processing; packaging and thermal management; theory and model i ng; and materials for revol utionary tech nologies.
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DoD Drivers with Potentially High Materials Impact The DoD drivers for future optoelectronic and Photonic materials can be divided into three categories: (1 ) weapons, (2)
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Materialswith high damagethreshold, fastmodulation capabilities, and low absorption are required. Materials for phase shifters with extremely low loss at h igh frequency are essential.
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Major materials challenges are focal plane arrays covering ultraviolet (UV) , IR, and very long wavelength IR regions.
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Nonlinear photonic crystals and nanostructured materials are also promising, as are metal-dielectric nanocomposites that can enhance the electrical field. Strong confinement of electrons in organic materials or quantum dots may lead to enhanced nonlinear optical coefficients.
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New EO polymers that are stable at higher temperatures are desired. Priorities for DoD Research in Optoelectronic and Photonic Materials il As the above discussion makes clear, most innovations in materials lie n clever engineering of materials in the nanometer (1 to 100 nm)
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Achieving photonic bandgap structures in all the wavelength regions of interest will be a grand challenge for materials processing. Electronic bandgap engineering can tailor the electronic and optical properties of materials.
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In addition to the potentially revolutionary technologies discussed, such as photonic bandgap engineering, other concepts such as optical computing are very exciting but will depend to a large degree on advances in materials for their real ization.
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Control of the structure and properties of materials on the nanoscale will present a tremendous challenge for materials processing. Microsystems Commercial Drivers Microsystems and MEMS are subjects of continuing R&D; commercial products are established and new applications are emerging.
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. With advances in materials processing, nano-electromechanical systems (NEMSs)
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Future military microsystems are likely to incorporate diverse materials, bringing to the fore issues of interfaces and materials compatibility. Such integration will pose similar challenges as methods of materials processing and fabrication of reduced dimension devices evolve.
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ng, displays, and information processing; Data storage and processing; Custom or combi natorial materials synthesis; and · Power generation. The panel evaluated the potential for exploiting these capabilities for defense applications, with particular attention to areas of possible revolutionary enhancement of performance.
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Transduction and Measurement of Small Forces and Masses The converse effect to the actuation of motion and mass transport is the detection of motion, small forces, and mass. The forces on micro- and nanostructured materials can be detected by a variety of physical processes, such as the creation of a voltage on a piezoelectric material.
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Enhanced sample capture, pretreatment, analysis, identification, and quantification will require incorporation of innovative materials or combinations of materials into systems using micromachining and related MEMS, MO EMS, or N EMS technologies. The design and selection of the sensor interface materials that interact with the target analyses are critically important.
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Available online at |
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, as discussed below. Microbolometer detectors, configured into focal-plane arrays (FPA)
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GaN-based wide-bandgap semiconductors are promisingfor blue and UV lasers, although a fundamental understanding ofthe material is still lacking. The lackofa lattice-matched substrate presents a challenge for epitaxial growth of high-quality crystals.
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Guidance from theory and modeling will be essential. Sample Manipulation, Fluid Control, and Thermal Management Microsystems for chemical and biological sensors or reactors (see below)
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Gas systems relying on suction- or pressure-driven mass transport using microscale diaphragm pumps are being considered for microsystem applications but scale unfavorably with miniaturization.4 The flexuralplate-wave approach (Moroney et al., 1991; Meng et al., 2000) , whereby gas flow could be achieved by acoustic streaming, has been suggested but not fully explored.
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Fluid motion could also be used for control of the optical or mechanical properties of devices. Other Novel Applications Important R&D activity is under way on MEMS devices and microsystems for optical devices, data processing, data storage, and displays, motivated by both defense and consumer applications such as telecommunications.
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, permitting integration of heteroarray sensors with each other and with Si-based circuitry and MEMS components. Such a monolithically integrated heteroarray could provide a wide variety of sensors with electronics and a full range of MEMS capability, but fabricating such a complex microsystem presents tremendous materials processing challenges.
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For microelectronics, the drive to higher densities, higher speeds, and smaller sizes increases the need for thermal management. Military devices and sensor-based Microsystems may be required to operate in hostile environments, placing even greater demands on electronics packaging.
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Mass flow control and chemical compatibility are emerging needs for many microsystem applications. Rationally designed polymeric, nanocomposite, and anisotropic materials assembled or implemented in a way that allows response amplification, show significant promise as chemical microsensor interface materials and as preconcentration and separation media.
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regimes of material behavior, where widely applicable modeling tools have not yet been developed. New Materials with Extreme Properties The increased functionality integrated into ever-decreasing volume drives the search for new materials that have properties (e.g., nonlinear optical properties)
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Packaging and Thermal Management Electronic and photonic materials will be integrated at increasingly greater scales in the coming decades. While the functionality that such systems provide will be staggering by today's standards, it comes at a price.
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Proceedings of the SPIE The International Society for Optical Engineering (Infrared Detectors and Focal Plane Arrays V, Orlando, FL, 14-1 7 April 1998)
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2000. The fractional free volume of the sorbed vapor in modeling the viscoelastic contribution to polymer-coated surface acoustic wave vapor sensor responses.
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Proceedings of the SPIE The International Society for Optical Engineering (Laser Processing of Materials and Industrial Applications II, Beijing, China, September 16-19, 1998)
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1998. Fluorescent porous polymer films as TNT chemosensors: Electronic and structural effects.
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