SBIR-STTR Award

The innovative proposed here is the development of a new type of radiation-discriminating, long-wavelength infrared (lwir) detector based on impurity-band-conduction (ibc). The new configuration enables one to discriminate between gamma-ray and lwir-induced events. Past use of ibc photodetectors has shown that injected dark current from the contacts is a major problem limiting their use. For the ibc configuration of interet here, the use of a bias-dependent superlattice (sl) tunneling structure is proposed is the exploitation of the fact that there is a critical bias below which ibc is essentially random and above which ibc is parallel to the electric field. This makes possible the storage of lwir-generated ionized donors and also the read-out of gamma-ray generated electrons and holes. The ionized donors areperiodically read-out and this forms the basis of lwir detection. Phase i would be a feasibility study, including the determination of the optimum device design, operating parameters, and expected current vs. Bias behavior in the presence of gamma-rays. This phase ii goal is the successful fabrication and testing of this device.

The innovation proposed here is the development of a new type of radiation-discriminating, long-wavelength infrared (LWIR) detector based on impurity-band-conduction (IBC). This new configuration shows promise for discriminating between gamma-ray and LWIR radiation. Conventional IBC photodetectors have the problem of injected dark current which greatly limits their use for radiation discrimination. For the device design proposed here, the use of a double-barrier quantum well (DBQW) structure is proposed as the means for blocking unwanted electron injection, but allowing for electron readout via resonant tunneling. The storage and subsequent readout of ionized donors enables one to discriminate between gamma and LWIR events. Phase I results have shown the theoretical feasibility of the proposed design. The objective of Phase II would be to demonstrate experimental feasibility by successful device fabrication and testing.