Surface electronic properties of n- and p-type InGaN alloys

X-ray photoemission spectroscopy is utilised to determine the variation in surface Fermi level pinning across the composition range of n- and p-type c-plane In(x)Ga(1-x)N alloys. The pinning relative to the charge neutrality level is used to explain a change in band bending direction causing a transition from surface electron accumulation (In rich) to depletion (Ga-rich), at x approximate to 0.43 for n-type alloys and a transition from surface inversion to hole depletion at x approximate to 0.59 for p-type alloys where downward band bending occurs across the composition range. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.