DIMINUTION OF THE SURFACE-STATES ON GAAS BY A SULFUR TREATMENT

The surface chemical properties of a GaAs layer grown by molecular bea m epitaxy were investigated by photoluminescence (PL) and photoreflect ance (PR) measurements. While the intensity of the PL spectra for the sulfur-treated GaAs, using a (NH4)2Sx solution, increased 75 times com pared to that for the as-grown GaAs, the peaks for the as-grown GaAs m easured by PR vanished after a sulfur treatment. These results indicat e that the surface state acting as the nonradiative recombination cent ers was passivated by the sulfur. The chemical adsorption behavior res ulting from the sulfur is discussed.