Electronic states in valence and conduction bands of group-III nitrides: Experiment and theory

• Published in: Physical review. B, Condensed matter and materials physics Vol. 61; no. 24
• Main Authors: Lawniczak-Jablonska, K., Suski, T., Gorczyca, I., Christensen, N. E., Attenkofer, K. E., Perera, R. C. C., Gullikson, E. M., Underwood, J. H., Ederer, D. L., Liliental Weber, Z.
• Format: Journal Article
• Language: English
• Published: United States 15-06-2000
• Subjects: ABSORPTION SPECTRA; ALUMINIUM NITRIDES; ANISOTROPY; BORON NITRIDES; CHEMICAL BONDS; ELECTRONIC STRUCTURE; ENERGY-LEVEL DENSITY; EXPERIMENTAL DATA; GALLIUM NITRIDES; INDIUM NITRIDES; MATERIALS SCIENCE; SYNCHROTRON RADIATION; THEORETICAL DATA; X-RAY EMISSION ANALYSIS
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.61.16623

A comprehensive study of the electronic structure of group-III nitrides (AlN, GaN, InN, and BN) crystallizing in the wurtzite, zinc-blende, and graphitelike hexagonal (BN) structures is presented. A large set of the x-ray emission and absorption spectra was collected at the several synchrotron radiation facilities at installations offering the highest possible energy resolution. By taking advantage of the linear polarization of the synchrotron radiation and making careful crystallographic orientation of the samples, the bonds along c axis ({pi}) and ''in plane'' ({sigma}) in the wurtzite structure could be separately examined. Particularly for AlN we found pronounced anisotropy of the studied bonds. The experimental spectra are compared directly with ab initio calculations of the partial density of states projected on the cation and anion atomic sites. For the GaN, AlN, and InN the agreement between structures observed in the calculated density of states (DOS) and structures observed in the experimental spectra is very good. In the case of hexagonal BN we have found an important influence of insufficient core screening in the x-ray spectra that influences the DOS distribution. The ionicity of the considered nitrides is also discussed. (c) 2000 The American Physical Society.