Control of as Diffusion using Ultrathin Metal Passivating Layers at GaAs(100) Surfaces

Abstract

We have performed low-energy cathodoluminescence spectroscopy (CLS) and synchrotron radiation photoemission (SXPS) measurements of Sb-passivated, clean and ordered molecular-beam epitaxy-grown GaAs(lOQ) surfaces. SXPS measurements show an effective stabilization of the surface As/Ga atomic ratio under annealing for Sb-passivated surfaces, in contrast to the variations in the surface stoichiometry observed for unpassivated GaAs(lOO) surfaces. Our CLS data provide evidence for the generation of deep level states during annealing to 550 °C in the GaAs(lOO) subsurface region. Fabrication of a passivating layer by annealing a 2 ML Sb layer on the GaAs(100) surface has been found to dramatically reduce the formation of this subsurface defective layer by inhibiting As desorption from the surface. Studies of A1 Schottky barrier formation on Sb-passivated layers demonstrate that the Schottky barrier value becomes independent of the detailsof processing, in contrast to the surface-dependent variations in barrier height observed for AI/GaAs(100) junctions without Sb passivating layers. © 1993, American Vacuum Society. All rights reserved.