HgCdTe Material Improvements for High Operating Temperatures

High performance HgCdTe infrared detector arrays operating at 77 K can be tailored for response across the infrared spectrum (1 to 14 micron and beyond), and are utilized in a variety of military and civilian systems for infrared imaging. Reducing cooling requirements allows integration in lighter and more compact systems. Good performance at higher operating temperatures can be provided by a system based on HgCdTe infrared detectors utilizing optimized material parameters (i.e. doping and defects) and non-equilibrium device architectures that suppress detector diffusion current, such as the PIN hetero-junction photodiode. This architecture can eliminate Auger generated diffusion current, resulting in a diodes whose performance is only limited by Shockley-Read (S-R) lifetime of the HgCdTe material. In Phase I, processes for molecular beam epitaxy (MBE) growth, doping and post-annealing will be optimized, resulting in a significant improvement in S-R lifetimes and hence depletion dark current. Integration of improved material into high performance photodetectors will be demonstrated. The efforts on material analysis and test diodes in Phase I will be extended to focal plane arrays in Phase II.