Electronic band structure of gallium nitride: a comparative angle-resolved photoemission study of single crystals and thin films

Angle-resolved photoemission measurements on gallium nitride single crystals and epitaxial thin films with wurtzite structure were performed using synchrotron radiation. Calculated theoretical final state bands were used to determine the corresponding k vectors in reciprocal space using the direct transition model. We were able to identify several previously unobserved features including several surface states and transitions to non-free-electron final states. Significant differences in the surface electronic band structure between thin film and single crystal samples were observed. 2002 Elsevier Science B.V. All rights reserved.