Epitaxial ZnSe on GaAs and Ge by HBr transport

Abstract

The conditions for forming epitaxial deposits of ZnSe on Ge and GaAs substrates were determined for the ZnSe HBr H 2, Zn Se HBr H 2 and Zn H 2Se HBr H 2 systems. Laue topography showed that Zn H 2Se HBr H 2 gave films of the greatest crystalline perfection, but the most rapid deposition rates were obtained with the ZnSe HBr H 2 system. Slower deposition rates did not always produce films of greater perfection, for crystalline perfection also was dependent on the reaction species. Deposition rates and crystalline perfection varied for different orientations. Films deposited on Ge substrates had greater crystalline perfection than those on GaAs substrates, but films on Ge substrates had a tendency to develop cracks. Doping with BBr 3 during deposition introduced donors in the ZnSe films and decreased the resistance of the films. Use of excess Zn during epitaxial growth with the ZnSe HBr H 2 system produced films having mobilities greater than 1000 cm 2/V-sec at 300°K. Photoluminescence studies indicated that the luminescence centers in ZnSe are related to Zn and/or Se vacancies or interstitials.