Growth and doping studies of CdTe epilayers on GaAs substrates by low-pressure plasma-radical-assisted metalorganic chemical vapor deposition

Abstract

Heteroepitaxial layers of CdTe were grown on GaAs substrates by the hydrogen-radical-assisted metalorganic chemical vapor deposition (MOCVD) technique at a low pressure and temperature. Dimethylcadmium and diethyltelluride were used as the source materials and hydrogen radicals produced in a remote plasma source by applying inductively coupled RF power were introduced into the reaction chamber. The growth was carried out in the substrate temperature range of 150–300°C, at a pressure of 0.2 Torr. The grown films, undoped, have high resistivities in the order of 10 5 Ω cm for the entire growth range. Gas-phase iodine doping to obtain n-type conductivity was carried by utilizing n-butyliodine as a dopant precursor, whereas p-type doping was achieved by employing nitrogen plasma radicals produced by nitrogen or ammonia gas in addition to hydrogen during the film growth. Highly conductive n- and p-type CdTe films with carrier concentration in the order of 10 18 cm −3 and mirror-like surface were obtained.