Surface structure and electronic states of sulfur-treated InP(1Â 1Â 1)A studied by LEED, AES, STM, and IPES

The structure and electronic states of an (NH4)2Sx-treated InP(1 1 1)A surface has been studied by using low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), scanning tunneling microscopy (STM), and inverse photoemission spectroscopy (IPES). The sample annealed in ultra-high vacuum (UHV) condition at ∼300-400 °C showed a 2 × 2-LEED pattern. Oval-shaped protrusions are observed in filled-state STM images. IPES intensity of the (2 × 2)-S surface at EF +1-3 eV and +4-6 eV is decreased by the (NH4)2Sx treatment. Based on these results, a plausible structural model is discussed.