Atomic-layer epitaxy control of Ge and Si in flash-heating CVD using GeH₄ and SiH₄ gases

Initial growth stages of Si and Ge in flash-heating CVD using SiH₄ and GeH₄ gases were investigated, in order to control the atomic-layer heteroepitaxy. It was found that Si was deposited on the Ge surface even at substrate temperatures below 300°C without the flash shot, and the deposited Si thickness increased with increasing the SiH₄ exposure time and saturated to a single atomic-layer thickness with a longer time to reach saturation at a lower temperature in the range of 200-300°C. In the case of Ge growth on a wet-cleaned Si surface, an incubation period was observed even with the flash shot. By increasing the flash light intensity and the GeH₄ partial pressure, the incubation period was reduced and a single atomic-layer growth of Ge on the wet-cleaned Si(100) was achieved with a single flash shot at 275°C.