GROWTH AND CHARACTERIZATION OF HOT-WALL EPITAXIAL CDTE ON (111) HGCDTE AND CDZNTE SUBSTRATES

Thin CdTe films were deposited by hot-wall epitaxy (HWE) on (111) HgCd Te and CdZnTe substrates at temperatures from about 140 to 335-degrees -C. X-ray rocking curves were used to show that crystal quality of the CdTe (111)B films improved as substrate temperature increased from 14 0 to about 250-degrees-C. Rocking curve values for full width at half maximum (FWHM) decreased from 2-4 degrees at 140-150-degrees-C to less than 100 arc-s at 250-degrees-C, and a FWHM of 59 arc-s was the lowes t value observed near 250-degrees-C. The FWHM of the HWE CdTe was foun d to be insensitive to growth rate below about 400 angstrom/min, but i ncreased to four degrees at 1250 angstrom/min. X-ray diffraction confi rmed that films grown on the B-face at higher temperatures were epitax ial, but contained a significant volume fraction, 35% to 50%, of rotat ional in-plane twins. Electron microscopy confirmed a coarse twin dens ity, and photoluminescence spectra showed an absence of excitonic emis sion in the HWE films. Simultaneous growth on two (111) HgCdTe substra tes with different surface polarities between 230-degrees-C and 335-de grees-C showed that deposition rate on the A-face decreased relative t o that on the B-face as temperature increased. Films grown on the B-fa ce exhibited better surface morphologies than those grown on the A-fac e.