Characterization of thin oxide films on GaAs substrates by optical methods and atomic force microscopy

In this paper the results of optical and atomic force microscopy characterization of oxide thin films prepared by thermal oxidation of GaAs single crystal wafers at a temperature of 500degreesC in air are presented. The optical characterization is performed using multi-sample modification of the method based on combining variable angle spectroscopic ellipsometry and near-normal spectroscopic reflectometry. It is shown that the films exhibit the rough lower boundaries and refractive index profile inhomogeneities. The spectral dependences of the refractive index and extinction coefficient of these films are presented within the wide spectral region, i.e., 210-900 nm. The values of the thicknesses and roughness parameters characterizing the oxide films are introduced as well. Copyright (C) 2004 John Wiley Sons, Ltd.