Large-Area Hybrid Substrates for HgCdTe Infrared Detectors

Mercury Cadmium Telluride, HgCdTe (MCT), is the most important material for modern infrared detectors and imaging arrays for wavelengths of strategic and tactical interest. Current substrates for HgCdTe detector deposition remain limited by high cost and severely limited available areas (CdZnTe bulk crystals), or by unacceptably large defect densities due to large material and thermal mismatch (Si wafers). New MCT substrate materials are desired with large areas (>300 cm2), low cost and good lattice and thermal match to the detector layer. In this SBIR project Structured Materials Industries, Inc. (SMI) proposes to develop a novel hybrid substrate material based on magnesium silicide (Mg2Si) layers on silicon substrates. Mg2Si has a good lattice match to MCT and has been shown in preliminary studies to have favorable thermal properties. In the proposed program SMI, working with a major manufacturer of MCT devices, will demonstrate the feasibility of utilizing Mg2Si/Si as a low cost, high-performance MCT substrate. In Phase I we will grow Mg2Si on silicon, characterize important material properties, and demonstrate single crystal deposition of MCT on the new substrates. Phase II will include optimization of the substrates, growth of MCT diode structures, and evaluation of IR detector performance. Commercial production of large area substrates and MCT devices will take place in Phase III.