The effect of external excitation on the sulphur passivation of GaAs surfaces

A simple chemical treatment using alkaline sulphides as an effective and robust means of surface passivation of GaAs has been widely studied. A new method of external excitation in the form of light and heat during sulphorization is investigated in the present study. This method of passivation is found to be more effective. The stoichiometry and the electronic properties of the passivated GaAs surfaces have been characterized by X-ray photoelectron spectroscopy, photoluminescence and I-V measurements on Schottky contacts. The recently proposed advanced unified defect model is found to explain the apparently contradictory results of decrease in surface state density accompanied by an increase in the surface band bending. © 1992.