Surface and Bulk Passivation effect of GaAs grown on Si Substrates by SeS 2 Treatment

The effect of selenium sulphide (SeS 2 ) treatment for GaAs grown on Si has been studied. The surface and bulk properties such as the photoluminscence intensity and minority carrier life-time have been significantly increased. The PL intensity showed a two fold and four fold increase for the as-passivated, passivated and annealed samples. It is proposed that the passivation on the surface occurs by means of sulphur and selenium atoms. The bulk passivation is by means of diffusion of Se into the bulk of the epilayer. Additional steps of annealing increased the minority carrier life time thereby reducing the recombination velocity and also indiffusion of Se helps to passivate the buried defects such as As Ga in the double heterostructures. Results obtained by X-ray photoelectron spectroscopy (XPS) reveal that sulfides and selenides reside on the outermost surface and only gallium based selenides are in the bulk of the GaAs layer.