Surface and bulk electronic structure of thin-film wurtzite GaN

Abstract

The bulk and surface valence-band electronic structure of thin-wurtzite GaN has been studied using angle-resolved photoemission spectroscopy. The bulk band dispersion along the {Gamma}{Delta}A, {Gamma}{Sigma}M, and {Gamma}TK directions of the bulk Brillouin zone was measured. Our results indicate the local-density approximation band-structure calculations using partial-core corrections for the Ga 3d states predict the relative dispersion of many of the observed bands with a high degree of accuracy. Furthermore, a nondispersive feature was identified near the valence-band maximum in a region of k space devoid of bulk states. This feature is identified as emission from a surface state on GaN(0001)-(1{times}1). The symmetry of this surface state is even with respect to the mirror planes of the surface and polarization measurements indicate that it is of sp{sub z} character, consistent with a dangling-bond state. {copyright} {ital 1997} {ital The American Physical Society}