Surface and bulk passivation effect of GaAs grown on Si substrates by SeS2treatment

The effect of selenium sulphide (SeS2) treatment for GaAs gl-own on Si has been studied. The surface and bulk properties such as the photoluminscence intensity and minority carrier lift-time have been significantly increased, The PL intensity showed a two fold and four fold increase for the as-passi vated, passivated and annealed samples. It is proposed that the passivation on the surface occurs by means of sulphur and selenium atoms. The bulk pas sivation is by means of diffusion of Se into the bulk of the epilayer. Addi tional steps of annealing increased the minority carrier life time thereby reducing the recombination velocity and also indiffusion of Se helps to pas sivate the buried defects such as AS(Ga) in the double heterostructures. Re sults obtained by X-ray photoelectron spectroscopy (XPS) reveal that sulfid es and selenides reside on the outermost surface and only gallium based sel enides are in the bulk of the GaAs layer.