Spontaneous and laser-enhanced halogen etching of GaAs(110)

Abstract

We review studies of surface morphologies associated with Cl and Br etching of GaAs(110) via thermal and laser activation, with an emphasis on the former. Using atomic-resolution scanning tunnelling microscopy, we examine the chemisorption structures, etch pit development and growth on terraces, step etching, the concentration dependence of various etching pathways, and the etching yields in the temperature range of 300-800 K. Surface structural changes are correlated with the underlying reaction processes and the stabilities of steps. Etch pit morphologies achieved by nanosecond laser-pulse irradiation of Br-covered GaAs(110) are compared with those obtained in spontaneous etching. We discuss etching mechanisms in light of the observed differences in etching morphology.