Automated Wafer Polishing for Epi-ready CdZnTe Substrates

MCT grown on CdZnTe substrates is the dominant material for infrared photon detectors. However, the technology for polishing CdZnTe substrates to the quality demanded by molecular beam epitaxy (MBE) does not currently exist in the United States. EPIR Technologies proposes to develop a technology for substrate polishing by (1) creating an advanced chemical polishing procedure for CdZnTe (2) creating a post-polish annealing procedure, and (3) growing MCT by MBE and fabricating photovoltaic devices. CdZnTe substrates that were previously used for MCT growth by MBE will be stripped of their MCT layers and polished (i.e. substrate reclamation or reclaiming). The reclaimed substrates will be characterized by atomic force microscopy, etch-pit density, profilometry, Hall, FTIR, and x-ray diffraction in the base period. In the option period, transmission electron microscopy will be employed to evaluate the atomic structure of the reclaimed substrates, and MCT heterostructures will be grown on the substrates. The development of this reclaiming technology will greatly reduce the cost of MBE-quality CdZnTe substrates and increase the yield of good MCT layers grown on CdZnTe by MBE. EPIR is committed to the development of MCT MBE technology and is the only commercial vendor of MCT by MBE in the United States.