A (NH4)2Sx-treated InSb(001) surface studied by using x-ray photoelectron spectroscopy, low-energy electron diffraction, and inverse photoemission spectroscopy

Abstract

A ${\mathrm{(NH}}_{\mathrm{4}}{)}_2{\mathrm{S}}_x$ -treated InSb(001) surface has been studied by using x-ray photoelectron spectroscopy, low-energy electron diffraction, and inverse photoemission spectroscopy (IPES). A thick sulfide layer is formed on the as-treated and annealed surfaces at less than about 400 °C. The thickness of the sulfide layer is estimated to be about 6–7 ML. Sulfur is bonded to both In and Sb in the as-treated surface layer although it is bonded only to indium in the layer annealed at more than 310 °C. A (2×1) structure appears for the treated surface annealed at 310 °C. The binding energy shift (−0.3 eV) of $\mathrm{In}{\text{\hspace{0.17em}3d}}_{\text{5/2}}$ and $\mathrm{Sb}{\text{\hspace{0.17em}3d}}_{\text{3/2}}$ is found for the (2×1) surface. The IPES spectra show that the density of states of unoccupied dangling bonds for surface indium is reduced by the $({\mathrm{NH}}_{\mathrm{4}}{)}_2{\mathrm{S}}_x$ treatment. The binding energy shift and structure of the sulfide layer are discussed.