Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 13: Postersitzung (Adsorption auf Oberfl
ächen, Oberfl
ächenreaktionen, Elektronische Struktur, Epitaxie und Wachstum, Halbleiteroberfl
ächen und Grenzfl
ächen, Oxide und Isolatoren)
O 13.68: Poster
Montag, 26. März 2001, 19:00–22:00, Foyer zu B
First-principles calculations of clean and hydrogen covered GaN (0001) and (0001) surfaces — •Fu-He Wang, Peter Krüger, and Johannes Pollmann — Institut für Festkörpertheorie, Universität Münster,Wilhelm-Klemm-Str. 10, 48149 Münster
In the present work we address ab-initio calculations of structural and electronic properties of clean and hydrogen covered GaN surfaces. We use the local density approximation of density functional theory employing supercells to determine energy-optimized surface structures. For a most accurate treatment of the electronic properties of these systems we employ our self-interaction and relaxation corrected pseudopotentials. In the case of the (1×1)-(0001) surface a monolayer of Ga adsorbed in T4 sites turns out to be the most stable structure under Ga-rich conditions while the clean surface is energetically preferred under N-rich conditions. For the (0001) surface a monolayer of Ga adatoms adsorbed in on-top positions is favored. The results of recent angle-resolved photoemission measurements can not be interpreted on the the basis of the calculated band structure for these configurations. Instead, only the surface band structure of the clean N-terminated GaN(0001) surface is in favorable agreement with experiment. Hydrogen atoms prefer to adsorb on top of the N atoms of the GaN(0001) surface. It is found that a coverage of 3/4 of a monolayer yields the most stable structure under hydrogen rich conditions. On the basis of a large variety of investigated adsorption configurations we discuss the possible role of hydrogen in the growth of GaN.
[1] Y.-C. Chao, Phys. Rev. B 59, R15586 (1999)