11:15 AM–1:51 PM, Wednesday, March 23, 2005
LACC - 406A
Sponsoring Unit:
DCMP
Chair: Dr. Tae-Sik Yoon, Dept. MSE, UCLA
Abstract ID: BAPS.2005.MAR.P18.8
12:39 PM–12:51 PM
Walter R.L. Lambrecht
Xiaoshu Jiang
M.S. Miao
(Case Western Reserve University)
Sukit Limpijumnong
(Suranaree University of Technology)
The Zn-vacancy is one of the dominant defects in ZnGeP$_2$. Its single negative charge state is EPR active. The hyperfine splitting shows that the unpaired electron is primarily localized on a pair of P atoms. In contrast, first-principles 64 atom supercell calculations using both the FP-LMTO and the VASP method of the $V_{Zn}^{-}$ state show that the defect maintains $S_4$ symmetry with the wave function spread equally over 4 P atoms. Here a group-theoretical analysis is presented. When including only the nearest neighbors, the system has $D_{2d}$ symmetry. While the one electron state of the unpaired electron is non-degenerate, a doubly degenerate $e$-state lies only about 10 meV below it. We show that a P-pairing distortion mode splits this $e$-state in two states which are even with respect to one of the mirrorplanes and odd with respect to the other and thus can only contain two of the P-dangling bonds. Calculations in which a pairing of P atoms is enforced while relaxing the remaining atoms confirm this model. Remaining puzzling aspects of this defect will be discussed.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.MAR.P18.8