XPS studies on nitridation of InP(100) surface by ion beam bombardment

Abstract

Ion beam nitridation (IBN) of InP at room temperature was studied as a function of both ion incident angle and energy. The InP surfaces were exposed to ion beam in an ultrahigh vacuum environment and the resulting surfaces were characterized in situ by small spot size x-ray photoelectron spectroscopy (XPS) for accurate determination of the surface composition and chemical state. Thin InN reaction layers were formed at all ion incident angles and ion energies whereas the formation of P - N bonds was not observed. However, the degree of nitridation of In decreases with increasing incident angle and ion energy, closely following the reduced incorporation of N at higher angles and ion energies. The variation in nitridation is smaller with ion energy in the 2 - 10 keV range than with ion incident angle. The observed angular and energy dependence of the N incorporation can be explained in terms of sputtering yields, indicating that the growth kinetics can be described as a dynamic process comprising the accumulation of N and sputter removal of the surface layer.