(NH_4)_2S_X-treated GaAs surfaces studied by soft x-ray photoelectron spectroscopy and S K-edge XANES

摘要

The sulfur chemical bonding states on (NH_4)_2S_X - treated GaAs surfaces have been studied by S1s core-level photoelectron and S K-edge fluorescence yield x-ray absorption near edge structure (XANES) using synchrotron radiation soft x-rays. The change in the sulfur chemical bonding states caused by annealing in vacuum after (NH_4)_2S_X -treatment was confirmed more clearly by spectral changes in both spectra than in the S2p photoelectron spectra. While four kinds of sulfur bonding states exist on the as-treated surfaces, only the S-Ga bonding state was detected on the surface after annealing. The spectra of S1s photoelectron and S K-edge XANES both suggested that annealing after the (NH_4)_2S_X - treatment is indispensable to achieve GaAs surface termination by S-Ga bonds.