Scanning Tunneling Microscopoy and surface Simulation of c-GaN(001)-4x1 Ga Tetramer Reconstruction

Hamad A. Albrithen 1,3Muhammed B. Haider 1Nancy Sandler 1Arthur R. Smith 1Pablo Ordejon 1,2

1. Ohio University (OU), Dept. of Physics & Astronomy, Athens, OH 45701, United States
2. Institut de Ciencia de Materials (ICMAB) - CSIC (ICMAB), Campus de la UAB, Barcelona 080193, Spain
3. King Saud University (KSU), P.O. Box 2455, Riyadh 11451, Saudi Arabia


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 [110] 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)

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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
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