Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals
Temperature-, excitation wavelength-, and excitation power-dependent photoluminescence (PL) spectroscopy have been utilized to investigate the orientation-modulated near band edge emission (NBE) and deep level emission (DLE) of ZnO single crystals (SCs). The near-band-edge emission of ZnO SC with &l...
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MDPI AG
2022-06-01
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| Series: | Nanomaterials |
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| author | Ali Hassan Abbas Ahmad Khan Yeong Hwan Ahn Muhammad Azam Muhammad Zubair Wei Xue Yu Cao |
| author_facet | Ali Hassan Abbas Ahmad Khan Yeong Hwan Ahn Muhammad Azam Muhammad Zubair Wei Xue Yu Cao |
| author_sort | Ali Hassan |
| collection | DOAJ |
| description | Temperature-, excitation wavelength-, and excitation power-dependent photoluminescence (PL) spectroscopy have been utilized to investigate the orientation-modulated near band edge emission (NBE) and deep level emission (DLE) of ZnO single crystals (SCs). The near-band-edge emission of ZnO SC with <0001> orientation exhibits strong and sharp emission intensity with suppressed deep level defects (mostly caused by oxygen vacancies V<sub>o</sub>). Furthermore, Raman analysis reveals that <0001> orientation has dominant E<sub>2</sub> (high) and E<sub>2</sub> (low) modes, indicating that this direction has better crystallinity. At low temperature, the neutral donor-to-bound exciton (D<sup>o</sup>X) transition dominates, regardless of the orientation, according to the temperature-dependent PL spectra. Moreover, free-exciton (FX) transition emerges at higher temperatures in all orientations. The PL intensity dependence on the excitation power has been described in terms of power-law (I~L<sup>α</sup>). Our results demonstrate that the α for <0001>, <1120>, and <1010> is (1.148), (1.180), and (1.184) respectively. In short, the comprehensive PL analysis suggests that D<sup>o</sup>X transitions are dominant in the NBE region, whereas oxygen vacancies (V<sub>o</sub>) are the dominant deep levels in ZnO. In addition, the <0001> orientation contains fewer V<sub>o</sub>-related defects with intense excitonic emission in the near band edge region than other counterparts, even at high temperature (~543 K). These results indicate that <0001> growth direction is favorable for fabricating ZnO-based highly efficient optoelectronic devices. |
| first_indexed | 2024-03-09T10:26:16Z |
| format | Article |
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| language | English |
| last_indexed | 2024-03-09T10:26:16Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-2595972e8ba34c55babcdb161a7d51202023-12-01T21:37:25ZengMDPI AGNanomaterials2079-49912022-06-011213219210.3390/nano12132192Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single CrystalsAli Hassan0Abbas Ahmad Khan1Yeong Hwan Ahn2Muhammad Azam3Muhammad Zubair4Wei Xue5Yu Cao6China International Science & Technology Cooperation Base for Laser Processing Robotics, Wenzhou University, Wenzhou 325035, ChinaDepartment of Physics and Department of Energy Systems Research, Ajou University, Suwon 16499, KoreaDepartment of Physics and Department of Energy Systems Research, Ajou University, Suwon 16499, KoreaDepartment of Physics, Faculty of Sciences, University of Central Punjab, Lahore 54000, PakistanCentre for Advanced Materials Application CEMEA, Slovak Academy of Sciences, Dubravska Cesta 9, 845 11 Bratislava, SlovakiaChina International Science & Technology Cooperation Base for Laser Processing Robotics, Wenzhou University, Wenzhou 325035, ChinaChina International Science & Technology Cooperation Base for Laser Processing Robotics, Wenzhou University, Wenzhou 325035, ChinaTemperature-, excitation wavelength-, and excitation power-dependent photoluminescence (PL) spectroscopy have been utilized to investigate the orientation-modulated near band edge emission (NBE) and deep level emission (DLE) of ZnO single crystals (SCs). The near-band-edge emission of ZnO SC with <0001> orientation exhibits strong and sharp emission intensity with suppressed deep level defects (mostly caused by oxygen vacancies V<sub>o</sub>). Furthermore, Raman analysis reveals that <0001> orientation has dominant E<sub>2</sub> (high) and E<sub>2</sub> (low) modes, indicating that this direction has better crystallinity. At low temperature, the neutral donor-to-bound exciton (D<sup>o</sup>X) transition dominates, regardless of the orientation, according to the temperature-dependent PL spectra. Moreover, free-exciton (FX) transition emerges at higher temperatures in all orientations. The PL intensity dependence on the excitation power has been described in terms of power-law (I~L<sup>α</sup>). Our results demonstrate that the α for <0001>, <1120>, and <1010> is (1.148), (1.180), and (1.184) respectively. In short, the comprehensive PL analysis suggests that D<sup>o</sup>X transitions are dominant in the NBE region, whereas oxygen vacancies (V<sub>o</sub>) are the dominant deep levels in ZnO. In addition, the <0001> orientation contains fewer V<sub>o</sub>-related defects with intense excitonic emission in the near band edge region than other counterparts, even at high temperature (~543 K). These results indicate that <0001> growth direction is favorable for fabricating ZnO-based highly efficient optoelectronic devices.https://www.mdpi.com/2079-4991/12/13/2192zinc oxidesingle crystalphotoluminescenceexcitonimpurities and defects |
| spellingShingle | Ali Hassan Abbas Ahmad Khan Yeong Hwan Ahn Muhammad Azam Muhammad Zubair Wei Xue Yu Cao Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals Nanomaterials zinc oxide single crystal photoluminescence exciton impurities and defects |
| title | Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals |
| title_full | Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals |
| title_fullStr | Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals |
| title_full_unstemmed | Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals |
| title_short | Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals |
| title_sort | orientation mediated luminescence enhancement and spin orbit coupling in zno single crystals |
| topic | zinc oxide single crystal photoluminescence exciton impurities and defects |
| url | https://www.mdpi.com/2079-4991/12/13/2192 |
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