We report an inverse photoemission study of the unoccupied states of thin-film n-type wurtzite GaN. For incident electron energies below 30 eV, free-electron bands do not provide a good description of the initial state. However, using a calculated quasiparticle band structure for the initial state, we can obtain good agreement between our measurements and the calculated low-lying conduction bands. No evidence of unoccupied surface states is observed in the probed part of the Brillouin zone, confirming earlier angle resolved photoemission studies, which identified the surface states on GaN(0001) as occupied dangling bond states, resonant with the valence band.

• Received 29 July 1998

DOI:https://doi.org/10.1103/PhysRevB.59.5003