Surface morphologies associated with thermal desorption: Scanning tunneling microscopy studies of Br–GaAs(110)

Abstract
Scanning tunneling microscopy was used to characterize the developing surface morphology found during typical temperature programmed desorption experiments for halogen–GaAs. Surfaces exposed to Br2 at 300 K were heated to temperatures between 450 and 675 K, followed by scanning at room temperature. This made it possible to relate the temperature-dependent gas phase etch product distribution to the surface structure and thereby examine atomic-level surface processes associated with the evolution of volatile products. We associate the desorption of GaBr3 around 500 K with the initiation of single-layer-deep terrace pits. Desorption of GaBr and As2 above 600 K accounts for the lateral enlargement of the pits.