XPS studies on nitridation of InP(100) surface by N+ 2 ion beam bombardment

Abstract

Ion beam nitridation (IBN) of InP at room temperature was studied as a function of both N+ 2 ion incident angle and energy. The InP surfaces were exposed to N+ 2 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 N+ 2 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.