Surface and bulk properties of GaAs (001) treated by Mg layers

Photoelectron spectroscopy was used to investigate the interactions which occur when Mg is deposited onto a GaAs (001) surface. The Mg, Ga and As core lines were deconvoluted into components whose angle dependence and intensity variation with overlayer thickness was used to interpret the reactions and morphology. The deposition of Mg causes the appearance of new chemically shifted components in Ga and As. This is interpreted as showing that the Mg initially diffuses into the GaAs and replaces the Ga which diffuses towards the surface, Further Mg deposition causes more in-diffusion but also creates a Mg overlayer. Annealing the sample to 500°C causes the overlayer to desorb together with the disappearance of most of the Mg in the lattice from the sampled layer. Some Mg-As however remains