ABSTRACT
Transition from GaAs(001)(2x6)-S to (2x3)-S surfaces was successfully observed by synchrotron radiation photoelectron spectroscopy(SRJPES), X-ray absorption near edge structure(XANES), and X-ray standing waves(XSW). With increasing substrate temperature, a (2x6) structure turns into a (2x3) structure at around 520 °C releasing about 20% surface sulfur atoms, observed by SRPES, which amount consist with the central dimer pairs of the (2x6) structure. The E polarization dependence in the SK-edge XANES spectra suggests that interdiffussion of S atoms should not be occurred, and that S atoms are still in the top layer bridge site even after high temperature annealing. Moreover, by XSW, it was found that, after the transition from the (2x6) to the (2x3), Ga-S-Ga bridge-bond formation was almost same as that of the (2x6). Therefore, by the transition, only the central dimer pairs of the (2x6) structure were released without interdiffussion and with keeping Ga-S-Ga bridge-bond formation.
