Deoxidation of gallium arsenide surface via silicon overlayer: A study on the evolution of the interface state density

The GaAs surface with the native oxide formed by wet etching has been gradually deoxidized via evaporation of a silicon overlayer. Both chemical and electronic properties of such structures have been examined by x-ray photoelectron spectroscopy (XPS) and “XPS under biases,” respectively. The latter technique enables a direct assessment of the interface state density of insulator∕semiconductor interfaces. We have concluded that gap states incident to the native oxide∕GaAs interface have annihilated due to replacement of Ga–O bonds by Ga–Si and As–Si bonds.