CHARACTERIZATION OF VAPOR-PHASE EPITAXIAL ZNSE FILMS

Properties of ZnSe films doped with donor impurities were investigated. The ZnSe films were grown at 350-degrees-C by using metallic zinc and selenium as the source materials; their vapors were transported separately by H-2 gas under atmospheric pressure. Iodine-doped ZnSe films were grown using CH3I (1000 ppm, diluted in helium) as a dopant source. However, it was necessary to stop this dopant flow during the film growth to obtain epitaxial films. HCl gas etching and evacuation of the reaction apparatus before the film growth began were employed to obtain epitaxial films and to avoid redistribution of impurities without heat-treatment at higher temperature. Secondary ion mass spectroscopy analysis indicated that both chlorine and gallium were included in the layers, as well as iodine, because of residual HCI gas. Optically high-quality and rather highly conductive n-type ZnSe films were obtained. Maximum electron concentration was 3.3 x 10(17) CM-3.