Abstract
The atomic and electronic structures and stability of native defects in a single-layer are investigated, based on density-functional theory calculations. Native defects such as a S vacancy (), a S interstitial (), a Mo vacancy (), and a Mo interstitial () are considered. The is found to have S-adatom configuration on top of a host S atom, and the has Mo- split interstitial configuration along the direction. The formation energies of the native defects in neutral and charged states are calculated. For the charged states, the artificial electrostatic interactions between image charges in supercells are eliminated by a supercell size scaling scheme and a correction scheme that uses a Gaussian model charge. It is found that the has a low formation energy of 1.3–1.5 eV in the Mo-rich limit condition, and the has 1.0 eV in the S-rich limit condition. The is found to be a deep single acceptor with the (0/) transition level at 1.7 eV above the valence-band maximum (VBM). The is found to be an electrically neutral defect. The Mo-related native defects of and are found to be high in formation energy above 4 eV. The is a deep single acceptor and the is a deep single donor, of which the (0/) acceptor and (+/0) donor transition levels are found at 1.1 and 0.3 eV above the VBM, respectively.
8 More- Received 15 July 2013
- Revised 17 March 2014
DOI:https://doi.org/10.1103/PhysRevB.89.205417
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