First-principles characterization of native-defect-related optical transitions in ZnO
Journal Article
·
· Journal of Applied Physics
- Naval Research Lab. (NRL), Washington, DC (United States). Center for Computational Materials Science
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of California, Santa Barbara, CA (United States). Dept. of Materials
- Univ. of Delaware, Newark, DE (United States). Dept. of Materials Science and Engineering
We investigate the electrical and optical properties of oxygen vacancies (VO), zinc vacancies (VZn), hydrogenated VZn, and isolated dangling bonds in ZnO using hybrid functional calculations. While the formation energy of VO is high in n-type ZnO, indicating that this center is unlikely to form, our results for optical absorption signals associated with VO are consistent with those observed in irradiated samples, and give rise to emission with a peak at less than 1 eV. Under realistic growth conditions, we find that VZn is the lowest-energy native defect in n-type ZnO, acting as an acceptor that is likely to compensate donor doping. Turning to optical transitions, we first examine NO as a case study, since N-related transitions have been identified in experiments on ZnO. Here, we also examine how hydrogen, often unintentionally present in ZnO, forms stable complexes with VZn and modifies its optical properties. Compared with isolated VZn, VZn-H complexes have charge-state transition levels lower in the band gap as well as have lower formation energies. These complexes also lead to characteristic vibrational frequencies which compare favorably with experiment. Oxygen dangling bonds show behavior mostly consistent with VZn, while zinc dangling bonds give rise to transition levels near the ZnO conduction-band minimum and emission peaking near 2.4 eV. Lastly, we discuss our results in view of the available experimental literature.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); US Army Research Office (ARO); US Department of the Navy, Office of Naval Research (ONR); USDOE
- Grant/Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1418932
- Report Number(s):
- LLNL-JRNL--735588
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 3 Vol. 122; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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