Optical spectroscopy of (001) GaAs and AlAs under molecular-beam epitaxy growth conditions

Abstract

Reflectance-difference (RD) studies were performed on variously reconstructed (001) GaAs and AlAs surfaces. The spectra of the (2×4) and (4×2) reconstructions on (001) GaAs show prominent features due to electronic transitions between lone-pair orbitals and dimer states, as previously identified by theoretical calculations. The spectra of the c(4×4) reconstructions on (001) GaAs and AlAs show similar features that we also interpret in terms of surface dimer excitations. These dimer features provide a capability of obtaining real-time, in situ information of dynamics on polar surfaces.