Desorption of InSb(001) native oxide and surface smoothing induced by low temperature annealing under molecular hydrogen flow

Abstract

The preparation of InSb (001) oxygen-free surfaces by thermal annealing at relatively low temperatures under molecular hydrogen flow is reported. This process is compared with thermal oxide desorption (TOD) at 400°C under ultrahigh vacuum conditions. Molecular hydrogen cleaning (MHC) at substrate temperature of 250°C and at hydrogen pressure of 5×10−6Torr resulted in complete desorption of the native oxide layer. Furthermore, no carbon contamination was observed on the surface following this treatment. The surface morphology of the samples following this process was found to be very smooth without any droplet structure. The In:Sb surface stoichiometry was nearly 1:1 along the MHC process. In addition, annealing the sample at 400°C in vacuum after oxide removal by MHC maintains the smoothness and the stoichiometry of the surface. In contrast, TOD at 400°C of an oxidized InSb surface in vacuum does not result in complete oxide removal from the surface. Furthermore, small droplets associated with In are produced at this annealing temperature. The surface stoichiometry shows In enrichment after TOD in vacuum above 360°C. The surface composition and chemical bonding were monitored by Auger electron spectroscopy and x-ray photoelectron spectroscopy as a function of process parameters. The surface morphology was analyzed by atomic force microscopy.