Lattice Matched Substrates for Mercury Cadmium Telluride growth by MBE

Many advanced HgCdTe (MCT) infrared detector structures are grown by the molecular beam epitaxy (MBE) technique, which is especially sensitive to small imperfections, impurities, precipitates, and polishing damage on the substrate surface. In order to achieve very high crystalline quality MCT structures, the substrate surface must be of superior quality (MBE-quality). EPIR demonstrated the ability to create superior CZT surfaces using innovative non-contact and pressure dependent polishing methods and our proprietary chemical polishing solutions. Our polished CZT substrates were qualified by growing MCT epi-layers by MBE. These MBE epi-layers exhibited state-of-the-art X-ray FWHM values and low (10^5 cm-2) etch pit density. In the Phase I effort, we will substantially improve the quality of our CZT substrate surfaces using the new, fully automated, ultra-high-precision polishing system designed and fabricated by EPIR. The system is capable of batch polishing very large (up to 64 cm^2) area substrates. We propose innovative ideas to create a true "epi-ready" CZT surface and eliminate the need for end-user surface pretreatments prior to MBE growth. We will grow and characterize MCT by MBE to qualify our polished substrates and work with our industrial partners to commercialize "epi-ready" MBE-quality CZT substrates.