Nitrogen K-edge NEXAFS measurements on group-III binary and ternary nitrides

It is demonstrated that the NEXAFS spectra are a "fingerprint" of the micro structure and the composition of the AlGaN and InGaN alloys. From the angul ar dependence of the NEXAFS spectra, the hexagonal symmetry of the compound s under study is deduced and the (p(x,) p(y)) or p(z) character of the fina l state is identified. The energy position of the absorption edge (E-abs) O f the binary compounds depends on the cation atomic number. The Eabs Of the AlGaN alloys takes values in between those corresponding to AlN and GaN; a s was expected. Contrary to that the absorption edge of In0.16Ga0.84N is re d-shifted relative to that of GaN and InN, probably due to ordering and/or phase separation phenomena.