Quantum-Engineered Long-Wavelength Infrared Photodetectors

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The objective of this program is to advance the understanding of quantum-engineered interband cascade (IC) structures and to develop high-performance long-wavelength infrared photodetectors (7-10 ?Ým). These quantum-engineered interband-cascade infrared photodetectors (ICIPs) will operate at elevated temperatures accessible by thermoelectric coolers (200 K) with high detectivity D* (~109 Jones or better). The intellectual merit is the integration of the discrete absorber architecture within a quantum engineered structure to form a detector based on new principles that combine the advantages of very fast intersubband relaxation, interband tunneling for carrier transport, and relatively slow interband transitions. With the discrete absorber architecture, ICIPs circumvent diffusion-length limitations and are feasible for high-speed operation without compromising their absorption quantum efficiency. Also, doping is unnecessary in ICIPs, but can be used as a means to manipulate carrier concentrations and transport without forming a conventional depletion region. By eliminating this depletion region, the Shockley-Read-Hall generation current is suppressed in ICIPs. Hence, this project will provide opportunities to investigate new phenomena associated with the underlying physics of quantum-engineered structures and devices.The broader impacts are the generation of cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures and devices; and the realization of high-performance and low-noise photodetectors in the long-wavelength infrared spectrum for many industrial, earth science, space exploration, and defense and homeland security applications. This project will offer students unique opportunities to pursue education, training and research in multidisciplinary topics. This project will promote the participation of faculty and students in statewide educational outreach activities.