Kinetics of native oxide film growth on epiready GaAs

The evolution of the native oxide layer on polished epiready GaAs wafers ha s been studied over a period of almost 2 years using grazing incidence X-ra y reflectivity and surface photoabsorption, Using computer-simulated reflec tivity profiles to fit the X-ray data, the thickness, density and effective roughness of the oxide layer was measured as a function of time. Surface p hotoabsorption measurements within a metal-organic vapour phase epitaxy rea ctor indicated that, after about 5 months, oxide species appeared that requ ired higher temperatures to desorb. There was no difference in the oxide sp ecies present for wafers stored in air or in an inert atmosphere. The data suggest that the thickening occurs by reaction of the oxide with the bulk s emiconductor material. (C) 2001 Elsevier Science B.V. All rights reserved.