Low temperature growth kinetics of SiGe alloys by disilane and germanium molecular beam epitaxy

Low temperature (≤500 °C) growth kinetics of SixGe1-x alloys by disilane and germanium molecular beam epitaxy has been studied. It is found that the germanium composition x increases with the decrease of substrate temperature in SiGe layers grown with constant disilane flow rate and fixed germanium cell temperature. On the other hand, in SiGe layers grown at a substrate temperature of 500 °C and a constant disilane flow rate, germanium composition x first increases with germanium cell temperatures, and then saturates at about 0.45 when further increase with germanium cell temperatures. This composition dependence behavior on substrate temperature and germanium cell temperature is different from that of SiGe grown using disilane and germane, which may be explained by the H atoms desorption limited growth kinetics.