Material quality characterization of CdZnTe substrates for HgCdTe epitaxy

Cd1-xZnxTe (CZT) substrates were studied to investigate their bulk and surface properties. Imperfections in CZT substrates affect the quality of Hg1-xCdxTe (MCT) epilayers deposited on them and play a role in limiting the performance of infrared (IR) focal plane arrays. CZT wafers were studied to investigate their bulk and surface properties. Transmission and surface x-ray diffraction techniques, utilizing both a conventional closed-tube x-ray source as well as a synchrotron radiation source, and IR transmission microspectroscopy, were used for bulk and surface investigation. Synchrotron radiation offers the capability to combine good spatial resolution and shorter exposure times than conventional x-ray sources, which allows for high-resolution mapping of relatively large areas in an acceptable amount of time. Information on the location of grain boundaries and precipitates was also obtained. The ultimate goal of this work is to understand the defects in CZT substrates and their effects on the performance and uniformity of MCT epilayers and then to apply this understanding to produce better infrared detectors.