Epitaxially grown semiconductor surfaces

Abstract

The atomic distributions on surfaces of Si, GaAs, HgTe and CdTe are studied as functions of temperature and substrate orientation in the [100], [111] and [111] directions. Surface entropy is calculated within the quasichemical approximation and the pair interaction energies are obtained using the tight-binding Green's function method. In most cases considered, the interactions between the atoms are attractive and they tend to congregate into islands for submonolayer coverage at temperatures below the roughening transition temperatures. Free energy curves for double-layer growth are presented. We find that growth in this case is mostly layer by layer as is often observed in atomic layer or molecular epitaxial growth. However, in cases such as Ga terminated [111] GaAs surfaces and most CdTe surfaces, the in-plane interactions are predicted to be repulsive. The calculated order-disorder transition temperatures for these cases are often much larger than usual growth temperatures and, consequently, incompletely filled surfaces are temperatures for these cases are often much larger than usual growth temperatures and, consequently, incompletely filled surfaces are expected to have domains in which atoms and vacancies arrange themselves in superlattice patterns.