Journal article
Incident wavelength and polarization dependence of spectral shifts in β-Ga 2 O 3 UV photoluminescence
Scientific reports, Vol.8(1), p.18075
12/24/2018
Handle:
https://hdl.handle.net/2376/106839
PMID: 30584263
Abstract
We report polarization dependent photoluminescence studies on unintentionally-, Mg-, and Ca-doped β-Ga
O
bulk crystals grown by the Czochralski method. In particular, we observe a wavelength shift of the highest-energy UV emission which is dependent on the pump photon energy and polarization. For 240 nm (5.17 eV) excitation almost no shift of the UV emission is observed between E||b and E||c, while a shift of the UV emission centroid is clearly observed for 266 nm (4.66 eV), a photon energy lying between the band absorption onsets for the two polarizations. These results are consistent with UV emission originating from transitions between conduction band electrons and two differentially-populated self-trapped hole (STH) states. Calcuations based on hybrid and self-interaction-corrected density functional theories further validate that the polarization dependence is consistent with the relative stability of two STHs. This observation implies that the STHs form primarily at the oxygen atoms involved in the original photon absorption event, thus providing the connection between incident polarization and emission wavelength. The data imposes a lower bound on the energy separation between the self-trapped hole states of ~70-160 meV, which is supported by the calculations.
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Details
- Title
- Incident wavelength and polarization dependence of spectral shifts in β-Ga 2 O 3 UV photoluminescence
- Creators
- Yunshan Wang - Department of Electrical and Computer Engineering, The University of Utah, Salt Lake City, UT, 84112, USAPeter T Dickens - Department of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USAJoel B Varley - Quantum Simulations Group, Materials Science Division, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USAXiaojuan Ni - Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT, 84112, USAEmmanuel Lotubai - Department of Electrical and Computer Engineering, The University of Utah, Salt Lake City, UT, 84112, USASamuel Sprawls - Department of Electrical and Computer Engineering, The University of Utah, Salt Lake City, UT, 84112, USAFeng Liu - Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT, 84112, USAVincenzo Lordi - Quantum Simulations Group, Materials Science Division, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USASriram Krishnamoorthy - Department of Electrical and Computer Engineering, The University of Utah, Salt Lake City, UT, 84112, USASteve Blair - Department of Electrical and Computer Engineering, The University of Utah, Salt Lake City, UT, 84112, USAKelvin G Lynn - Department of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USAMichael Scarpulla - Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT, 84112, USA. scarpulla@eng.utah.eduBerardi Sensale-Rodriguez - Department of Electrical and Computer Engineering, The University of Utah, Salt Lake City, UT, 84112, USA. berardi.sensale@utah.edu
- Publication Details
- Scientific reports, Vol.8(1), p.18075
- Academic Unit
- Electrical Engineering and Computer Science, School of
- Publisher
- England
- Grant note
- DE-AC52-07NA27344 / U.S. Department of Energy (DOE) FA9550-18-1-0507 / United States Department of Defense | United States Air Force | AFMC | Air Force Office of Scientific Research (AF Office of Scientific Research) DMR #1121252 / National Science Foundation (NSF)
- Identifiers
- 99900547101701842
- Language
- English
- Resource Type
- Journal article