Effects of NH 3 on the growth rate and the surface morphology of GaAs in chloride VPE

Abstract

Effects of ammonia (NH 3) on the growth rate and the surface morphology of GaAs were studied in chloride vapor phase epitaxy (C-VPE). We found that the NH 3 addition increases the growth rate at the substrate temperatures of 640–680°C, but does not at higher temperatures in a conventional C-VPE method. For a single flat temperature zone (SFT) C-VPE method, an increase of the growth rate due to the NH 3 addition was not observed in any growth temperature range. These results indicate that the NH 3 addition enhances only the desorption of GaCl 3, which is the rate determining step of conventional C-VPE at low temperatures. In addition to that, we found that the NH 3 addition greatly suppressed the formation of hillocks which were often observed on the GaAs surface grown on (001)just-oriented substrates. A simple model of the mechanism will be proposed.