Book Description

The incorporation and amphoteric behavior of Group IV impurities in high purity gallium arsenide (GaAs) and indium phosphide (InP) grown by various growth techniques have been quantitatively studied by employing the characterization techniques, Hall-effect measurements, photothermal ionization spectroscopy (PTIS), and photoluminescence (PL). These quantitative analyses have been made on over 500 different GaAs samples provided from about 50 different laboratories and 50 different InP samples from 15 different laboratories as grown by the growth techniques of liquid phase epitaxy (LPE), vapor phase epitaxy (VPE), molecular beam epitaxy (MBE), and metalorganic chemical vapor deposition (MOCVD). With these quantitative analyses, the incorporation and amphoteric behavior of Group IV impurities have been correlated with the growth techniques and various independent growth parameters, particularly V/III ratios and substrate orientations. The spectroscopic analysis indicates that the relative ordering of central cell correction of shallow donor impurities in InP are identical to that of GaAs, but the amphoteric behavior of Si in LPE InP is opposite to that in LPE GaAs. Although Ge was always more amphoteric than Si, the values of amphoteric ratios of both Si and Ge in GaAs (100) layers were not noticeably changed with varying V/III ratios or other growth conditions for all of the growth techniques. The orientation dependent amphoteric behavior of Si, Ge, and C in MBE and AsCl$sb3$-MBE GaAs samples strongly suggests that the surface kinetic reactions during epitaxial growth play the dominant role in the amphoteric behavior. Obviously, the above results on the amphoteric behavior cannot be explained by the simple equilibrium thermodynamic consideration alone. The surface kinetic model has been developed to explain the amphoteric behavior of Group IV impurities in MBE and VPE GaAs. The major surface reactions for impurity incorporation involve adsorption, surface diffusion, dissociative chemisorption, and desorption, which are the rate limiting processes that can be different for different substrate orientation and different chemical impurity and/or source species used for the different growth techniques.