Ga–S–Ga bridge-bond formation on in-situ S-treated GaAs 001/ surface observed by synchrotron radiation photoemission spectroscopy, X-ray absorption near edge structure, and X-ray standing waves

The chemical and structural changes of an in-situ S-treated GaAs 001.surface induced by thermal treatments were studied by synchrotron radiation photoemission spectroscopy SRPES., X-ray absorption near edge structure XANES., and X-ray standing waves XSW.. SRPES results revealed that As–S chemical states in the As 3d core level disappear from the surface with annealing at 4008C. S K-edge XANES spectra showed that most of the S atoms are in a S–Ga chemical state after annealing at about 350–4008C. XSW results suggested that the exchange reaction between the S and As atoms begins to occur at an annealing temperature lower than 3008C, and that the Ga–S–Ga bridge-bond formation is almost completed with annealing at about 350–4008C. q1998 Elsevier Science B.V. All rights reserved