Electronic structure of GaN(0 0 0 1̄)-(1 × 1) surface

The (0 0 0 1̄) (N-polar) (1 × 1) surface of bulk gallium nitride crystals has been investigated by means of angle-resolved photoemission spectroscopy. The surface was prepared by repeated cycles of Ar+ ion sputtering and annealing. The electronic band structure was explored along the Γ–A and Γ–K–M directions of the Brillouin zone, by measuring normal and off-normal photoemission spectra. A similar set of data was also collected for the same surface subjected to Ga deposition under MBE conditions. The identification of bulk and surface related spectral features was based on analysis of the acquired experimental data and supported by comparison with the results of available band structure calculations. The features characteristic of both (1 × 1) N-terminated and (1 × 1) Ga-adlayer terminated surface configurations were revealed for the surface under investigation.