AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS1-MoM

Paper SS1-MoM6
Surface Electronic Structure of Wurtzite GaN(0001)1x1 Studied with Angle-Resolved Photoemission

Monday, November 2, 1998, 10:00 am, Room 308

Session: Issues in Surface Electronic Structure
Presenter: Y.-C. Chao, Boston University
Authors: Y.-C. Chao, Boston University
C.B. Stagarescu, Boston University
J. Downes, Boston University
K.E. Smith, Boston University
D. Hanser, North Carolina State University
M. Bremser, North Carolina State University
R.F. Davis, North Carolina State University
Correspondent: Click to Email
The surface electronic structure of the n-type, Si-doped, wurtzite GaN(0001)1x1 surface has been studied in detail with angle-resolved photoemission. The GaN film was grown on a AlN buffer layer on a 6H-SiC(0001) Si-face, on-axis substrate using a low-pressure metalorganic vapor phase epitaxy technique. A very sharp 1x1 LEED pattern was observed from the surface after the cleaning by repeated cycles of sputtering with nitrogen ions and annealing in ultra-high vacuum. The photoemission spectra reveal a previous unidentified highly dispersive surface-state band. The dispersion of this surface state has been determined along the [@GAMMA@KM] azimuthal direction of the 1x1 surface Brillouin zone. At @GAMMA@ point, the surface state is located at ~2 eV below the valence band maximum. For small emssion angles, this surface state rapidly disperses towards the VBM by ~1 eV. As the emssion angle is increased, the state starts to disperse downward and moves into the projected bulk band gap close to the K point. The identification of this state as originating from a surface band is confirmed by exposure of the surface to activated hydrogen. The intensity of emission from the surface state decreases dramatically following H exposure. This work was supported in part by the National Science Foundation under grant umber DMR-95-04948.