Removal of the sulfur passivation overlayer on a (NH4)2Sx-treated GaAs surface by vacuum-ultraviolet irradiation

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Abstract
Effects of photon irradiation on the chemical state of a (NH4)2Sx‐treated GaAs surface have been investigated using photoemission and photon‐stimulated desorption (PSD) spectroscopic techniques with synchrotron radiation (SR). It is shown that a sulfur‐passivation overlayer on the (NH4)2Sx‐treated GaAs surface is readily removed by irradiating SR in the vacuum‐ultraviolet (VUV) region onto the surface, suggesting the possibility of cleaning the sulfur‐passivated GaAs surface by VUV irradiation. The dominant PSD ion product that desorbs from the sulfur‐passivated GaAs surface during VUV irradiation is found to be H+. No desorption of sulfur ions is observed, which suggests that sulfur adatoms desorb as neutral species.