(NH4)(2)S-X-TREATED INAS(001) SURFACE STUDIED BY X-RAY PHOTOELECTRON-SPECTROSCOPY AND LOW-ENERGY-ELECTRON DIFFRACTION

The chemical state of sulfur on (NH4)(x)S-x-treated InAs(001) and ther mal stability of the surface have been studied by high-resolution x-ra y photoelectron spectroscopy and low-energy electron diffraction, We f ind sulfur bonded to In and As atoms but no elemental sulfur for the a s-treated surface. The binding energies of S 2p for sulfur bonded to I n and As an very close. Only one chemical state in sulfur bonded to In is found, in contrast with treated GaAs(001), GaP(001), and InP(001) with two. The sulfur bonded to As atoms is desorbed upon annealing the sample at 300 degrees C in a vacuum. A diffuse (1X1) surface observed on the as-treated sample is reconstructed to a (2X1) structure upon a nnealing at 350 degrees C, which is different from a(1X2) structure fo r GaP(001) and InP(001).