New Material System for 3rd Generation IR Applications

Report No. ARL-TR-5418
Authors: Gregory Brill and Yuanping Chen
Date/Pages: December 2010; 24 pages
Abstract: Much progress has been made in developing high quality mercury cadmium telluride (HgCdTe)/silicon (Si) for large area long wavelength infrared (LWIR) focal plane array (FPA) applications. However, even with all the material advances made to date, there is no guarantee that this technology will be mature enough to meet FPA specifications for a fielded system. With this in mind, the U.S. Army Research Laboratory (ARL) has begun investigating mercury cadmium selenide (HgCdSe) for infrared (IR) applications. Analogous to HgCdTe, HgCdSe is a tunable semiconductor that can detect any wavelength of IR radiation through control of the alloy composition. Additionally, several mature, large area bulk III-V substrates are nearly lattice matched to HgCdSe, giving this system a possible advantage over HgCdTe, for which no scalable, bulk substrate technology exists. We have initiated a study of the growth of HgCdSe using molecular beam epitaxy (MBE). Growth temperature and material flux ratios were varied to ascertain the best growth conditions. Smooth surface morphology has been achieved using a growth temperature much lower than HgCdTe (~80 ¿C lower). Additionally, no void defects were nucleated at these lower temperatures. Results suggest a linear relationship between the Se/Cd flux ratio and the cut-off wavelength.
Distribution: Approved for public release
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Last Update / Reviewed: December 1, 2010