Scanning Tunneling Microscopoy and surface Simulation of c-GaN(001)-4x1 Ga Tetramer Reconstruction
|Hamad A. Albrithen 1,3, Muhammed B. Haider 1, Nancy Sandler 1, Arthur R. Smith 1, Pablo Ordejon 1,2|
1. Ohio University (OU), Dept. of Physics & Astronomy, Athens, OH 45701, United States
Scanning tunneling microscopy images of c-GaN(001)-4×1 acquired at both positive and negative sample biases show that the surface consists of "tetramer" rows aligned along  with a spacing along [1-10] of 12.8 Å, or 4-atomic spacings. Dual-bias imaging indicates a shift of the corrugation maximum position by 180o as the sample bias changes sign. Simulated images of the surface reconstruction based on the 4×1 linear tetramer model by Neugabauer et al.,(1) confirm the STM data, showing the occupied states peak at the middle of the tetramer and the unoccupied states peak between tetramers. Scanning tunneling spectroscopy also shows the semi-insulating nature of the 4×1 reconstruction, having a surface gap of 1.3 ± 0.1 eV, as also predicted by theory. Higher Ga coverage on the surface shows a variety of Ga-adatom reconstruction.
(1) Neugebauer et al., Phys. Rev. Lett. 80, 3097(1998)
Presentation: poster at E-MRS Fall Meeting 2005, Symposium F, by Hamad A. Albrithen
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-14 08:57 Revised: 2009-06-07 00:44