Surface states on GaN(0 0 0 1̄)(1×1)––an angle-resolved photoemission study

We present the results of angle-resolved photoemission studies on the (0 0 0 1̄) (N-polar) surface of bulk gallium nitride crystals. The bulk and surface band structure was investigated along Γ–A and Γ–K–M directions on the surface with (1×1) symmetry. The sets of spectra were obtained in normal and off-normal emission for the surface prepared by Ar+ ion sputtering and annealing and for the same surface enriched with Ga under molecular beam epitaxy conditions. The bulk and surface related features were identified by analysis of the acquired experimental data and by comparison with the results of band structure calculations.