Photoemission studies on GaN(0 0 0 (1)over-bar) surfaces

We present the results of photoemission studies on (0 0 0 (1) over bar) (N- polar) surfaces of bulk gallium nitride crystals. The procedures that yield clean and well-ordered (0 0 0 (1) over bar) (1 x 1) surfaces were develope d and tested. The surface crystallinity was assessed by low-energy electron diffraction. Angle-resolved photoemission spectroscopy with synchrotron ra diation was used to determine the valence-band electronic structure of GaN along the Gamma-Delta -A direction of the Brillouin zone. The band structur e derived from our experimental data is compared with the results of recent band structure calculations. (C) 2001 Elsevier Science B.V. All rights res erved.