Molecular beam epitaxy of HgCdTe on (211)B CdZnTe

The recent research results on molecular beam epitaxy of HgCdTe on CdZnTe were presented. The CdZnTe substrates mounting process, under protective atmosphere, was essential to avoid substrate oxidation. It was demonstrated by in-situ reflection high-energy electron diffraction (RHEED), during deoxide process. Concerning the poor thermal conductivity of CdZnTe, good uniformity of HgCdTe on CdZnTe is hard to obtained, compared with the epitaxy on GaAs or Si. It was found that the crystal quality of HgCdTe/CdZnTe was strongly temperature dependent. According to good morphology, crystal quality and maintenance efficiency, the proper growth temperature range of HgCdTe/CdZnTe is 191~193°C. By the enhanced thermal contact sticking during substrate mounting, the uniformity of HgCdTe on CdZnTe was improved, including Cd composition, morphology, as well as crystal quality. In addition, proper in-suit high temperature anneal can reduce dislocation density of HgCdTe epilayers about half order of magnitude. High quality uniform HgCdTe epilayers on 30mm×30mm CdZnTe Substrates were obtained under the optimized growth condition. The X-ray double-crystal rocking curve (XDRC) full-width at half-maximum (FWHM) values vary in a range of 20~30 arcsec. EPD values are bellow 2×10 5 cm -2 , with the best result of 3×10 4 cm -2 .