We report first-principles investigation of the electronic structure, atomic geometry and formation energy of the isolated substitutional oxygen impurity (OAs) and the oxygen-hydrogen pair complex (OAs-H) in GaAs. Our results for OAs in neutral charge state, show an on-site defect with an A1 midgap level occupied with one electron. The OAs-2 charge state shows an off-center displacement of 0.7 Å on the < 111 > direction associated to a JT distorion. The calculated formation energy reveal a negative-U behavior for the doubly negative charge state. For the neutral complex OAs-H, we calculated the total energy and atomic configuration for seven different positions of hydrogen atom with oxygen in the same substitutional site. The lowest energy configuration obtained from our calculations has hydrogen near a bond-center site of OAs-Ga bond, with OAs-H bond length of 1.88 Å and H-Ga of 1.54 Å. The angle between these bonds is found to be 160°. The hydrogen passivation of the impurity level is observed.
|Number of pages||8|
|Journal||Brazilian Journal of Physics|
|Publication status||Published - Dec 1997|
ASJC Scopus subject areas
- Physics and Astronomy(all)