Novel Wavelength Tailorable Heterojunctions For Infrared (IR)Detection

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The proposed project involves research on Heterojunctions concepts, for developing infrared detectors having potential applications in important areas such as spectroscopy in chemistry and biology, optical communication, plasma diagnostics, medical and biological imaging systems, and astrophysics. In the previous NSF program, emphasis was on QWIP detector formats for IR detection and the improvement of the performance by understanding transient effects. Here the development of tailorable solid state IR detectors for 3-30 um (100-10 THz) range (a technologically important region for a wide range of applications) is proposed. These detectors show better performance (responsivity, efficiency, operating temperature and D*) than the available detectors. Recent breakthroughs in THz generation have started bridging the gap between terahertz frequencies and the frequencies above and below. However, in THz detector development, extreme cooling capabilities are still a requirement as in superconducting hot electron bolometers. In order for the field to develop substantially, both source and detectors should develop at the same pace. The primary goal of this proposal will he to design and characterize detectors based on a novel concept [heterojunction interfacial workfunction internal photoemission (HEIWIP)] and optimize the devices for various frequency (wavelength) ranges. The work will include both experimental and theoretical effort studying the role of device parameters on the performance including doping, barrier parameters, layer thickness, resonance cavity effects and dark current issues. In collaboration with scientists at other universities (Cornell), national laboratories (NRC - Canada and U.S. Army Research Lab) and other institutes (Institute for Physics of Microstructures, Nizhny Novgorod) these problems will be addressed by exploring structures grown by different groups and different methods. Optimized designed features, well-doping profiles, energy-selective barriers, emitter/collector barriers, etc. will be modeled and incorporated.The high national importance of this cutting-edge technology, and the close involvement of highly qualified staff and students at Georgia State with our collaborators will continue to impact significantly on advancing knowledge, and physics and engineering education, making a significant contribution to the nation's science and technology base by supplying the scientific community with leading young scientists. The collaborations will also ensure effective transfer to emerging high-tech applications both in commercial and government laboratories. The results of the proposed research will vastly improve the understanding of detectors and form the basis for the next generation of THz detectors.