Surface reaction mechanism in Si and GaAs crystal growth

Abstract

In the field of applied crystal growth we have investigated the mechanism of crystal growth on semiconductors in each reaction step: gas-phase reaction, adsorption, surface reaction, and sticking to a stable site of the substrate. In this review mainly the investigations and the results of the reactions or the processes occurring on the substrate surface are described. In the case of epitaxial growth of Si, the formation of SiCl 2 was ascertained both by IR-absorption spectroscopy in the gas phase of the atmospheric pressure system and by mass spectroscopy in the surface reaction of molecular layer epitaxy. Migration of the adsorbate is important to form a high-quality crystal of Si. From the observation of pyramidal hillocks and the deformation of tables which were artificially formed on the substrate, surface migration is discussed. In GaAs epitaxy the gas-phase reaction was investigated by means of IR-absorption spectroscopy. An intermediate species which showed an absorption peak at 2080 cm -1 was detected. Molecular layer epitaxy was achieved by alternate injection of trimethyl gallium (TMG) as Ga source and AsH 3 as arsenic source. The formation of monolayer adsorption species closely depends on the surface reaction producing GaCH 3. In another case that multilayer growth occurs, the dominant surface reaction is the decomposition of TMG into Ga.