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

A (NH4)(2)S-x-treated InSb(001) surface has been studied by using x-ray pho toelectron spectroscopy, low-energy electron diffraction, and inverse photo emission spectroscopy (IPES). A thick sulfide layer is formed on the as-tre ated and annealed surfaces at less than about 400 degrees C. The thickness of the sulfide layer is estimated to be about 6-7 ML. Sulfur is bonded to b oth In and Sb in the as-treated surface layer although it is bonded only to indium in the layer annealed at more than 310 degrees C. A (2 x 1) structu re appears for the treated surface annealed at 310 OC. The binding energy s hift (-0.3 eV) of In 3d(5/2) and Sb 3d(3/2) is found for the (2 x 1) surfac e. The IPES spectra show that the density of states of unoccupied dangling bonds for surface indium is reduced by the (NH4)(2)S-x treatment. The bindi ng energy shift and structure of the sulfide layer are discussed. (C) 1999 American Vacuum Society. [S0734-2101(99)03702-1].