Analysis of sulfide layer on gallium arsenide using X-ray photoelectron spectroscopy

The increasing use of the III–V compound semiconductors in electronic devices has created a pressing need to develop a good passivant to reproducibly control their surface properties. Ultrathin sulfur passivation of GaAs stabilizes its surface or interface very well and reduces the interface states density. However, the passivated surface exhibits a substantial degradation due to the exposure to air after passivation. In this study, the effect of growing a thick non-degradable sulfide layer by non-aqueous ammonium polysulfide anodization on the GaAs surface was investigated using X-ray photoelectron spectroscopy (XPS). The surface chemistry of this amorphous sulfide layer indicated a relationship between the atomic structure and the property of the interface state. The depth profile of the passivation layer revealed that the structure of the thick sulfide/GaAs interface includes a Ga2S3 rich layer on the surface and homogeneous distribution of GaS, Ga2S3, As2S5 and GaAs in the bulk of the insulator layer.