Single-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperature
High-quality, single-crystal-like Cu2O thin films of various thicknesses (10 nm–45 nm) were prepared at a low temperature (150 °C) by controlling layer-by-layer oxidation of wafer-scale Cu thin films sputtered along the (111) direction using a pure single-crystal Cu target. The cross-sectional image...
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2019-03-01
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| Series: | APL Materials |
| Online Access: | http://dx.doi.org/10.1063/1.5087114 |
| _version_ | 1828743159496048640 |
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| author | Taewoo Ha Inhee Park Kyung Ik Sim Howon Lee Jong-Sung Bae Su Jae Kim Jong Phil Kim Teun-Teun Kim Jae Hoon Kim Joon Ik Jang Se-Young Jeong |
| author_facet | Taewoo Ha Inhee Park Kyung Ik Sim Howon Lee Jong-Sung Bae Su Jae Kim Jong Phil Kim Teun-Teun Kim Jae Hoon Kim Joon Ik Jang Se-Young Jeong |
| author_sort | Taewoo Ha |
| collection | DOAJ |
| description | High-quality, single-crystal-like Cu2O thin films of various thicknesses (10 nm–45 nm) were prepared at a low temperature (150 °C) by controlling layer-by-layer oxidation of wafer-scale Cu thin films sputtered along the (111) direction using a pure single-crystal Cu target. The cross-sectional images of the thin films reveal high crystallinity of Cu2O layers except for 60° twinning in the sequential stacking order as evidenced by high-resolution transmission electron microscopy, which is consistent with the absence of the photoluminescence (PL) signals arising from atomic-scale vacancies. The optical properties of our Cu2O films were investigated using temperature-dependent PL and Raman spectroscopy. All of the Cu2O thin films exhibit characteristic band-to-band transitions together with the series of yellow excitonic transitions slightly below the fundamental bandgap. The spectral locations for the PL are approximately consistent with those for the bulk counterpart. The excellent optical quality of our Cu2O was further demonstrated by significantly reduced quasi-direct transition that occurs at symmetry-breaking crystal imperfection, which relaxes the stringent momentum conservation rule. We identified the three main Raman scattering modes of the Cu2O thin films, where the two forbidden modes of Γ15(1) and Γ12−+Γ25− are resonantly allowed by the proximity of the incident photon energy to the green bandgap. We believe that our synthesis technique can be utilized for the preparation of single-crystal-like metal oxide thin films at low production temperatures with precise thickness control for the development of novel optoelectronic devices and for the exploration of the nanoscale light-matter interaction as well. |
| first_indexed | 2024-04-13T01:32:54Z |
| format | Article |
| id | doaj.art-29dea752b8f7439f9c2a2503db32a390 |
| institution | Directory Open Access Journal |
| issn | 2166-532X |
| language | English |
| last_indexed | 2024-04-13T01:32:54Z |
| publishDate | 2019-03-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | APL Materials |
| spelling | doaj.art-29dea752b8f7439f9c2a2503db32a3902022-12-22T03:08:28ZengAIP Publishing LLCAPL Materials2166-532X2019-03-0173031115031115-710.1063/1.5087114012903APMSingle-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperatureTaewoo Ha0Inhee Park1Kyung Ik Sim2Howon Lee3Jong-Sung Bae4Su Jae Kim5Jong Phil Kim6Teun-Teun Kim7Jae Hoon Kim8Joon Ik Jang9Se-Young Jeong10Department of Physics, Yonsei University, Seoul 03722, South KoreaDepartment of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, South KoreaDepartment of Physics, Yonsei University, Seoul 03722, South KoreaDepartment of Physics, Yonsei University, Seoul 03722, South KoreaDivision of Analysis and Research, Pusan Center, Korea Basic Science Institute, Busan 46742, South KoreaCrystal Bank Research Institute, Pusan National University, Busan 46241, South KoreaDivision of Analysis and Research, Pusan Center, Korea Basic Science Institute, Busan 46742, South KoreaCenter for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, South KoreaDepartment of Physics, Yonsei University, Seoul 03722, South KoreaDepartment of Physics, Sogang University, Seoul 04107, South KoreaDepartment of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, South KoreaHigh-quality, single-crystal-like Cu2O thin films of various thicknesses (10 nm–45 nm) were prepared at a low temperature (150 °C) by controlling layer-by-layer oxidation of wafer-scale Cu thin films sputtered along the (111) direction using a pure single-crystal Cu target. The cross-sectional images of the thin films reveal high crystallinity of Cu2O layers except for 60° twinning in the sequential stacking order as evidenced by high-resolution transmission electron microscopy, which is consistent with the absence of the photoluminescence (PL) signals arising from atomic-scale vacancies. The optical properties of our Cu2O films were investigated using temperature-dependent PL and Raman spectroscopy. All of the Cu2O thin films exhibit characteristic band-to-band transitions together with the series of yellow excitonic transitions slightly below the fundamental bandgap. The spectral locations for the PL are approximately consistent with those for the bulk counterpart. The excellent optical quality of our Cu2O was further demonstrated by significantly reduced quasi-direct transition that occurs at symmetry-breaking crystal imperfection, which relaxes the stringent momentum conservation rule. We identified the three main Raman scattering modes of the Cu2O thin films, where the two forbidden modes of Γ15(1) and Γ12−+Γ25− are resonantly allowed by the proximity of the incident photon energy to the green bandgap. We believe that our synthesis technique can be utilized for the preparation of single-crystal-like metal oxide thin films at low production temperatures with precise thickness control for the development of novel optoelectronic devices and for the exploration of the nanoscale light-matter interaction as well.http://dx.doi.org/10.1063/1.5087114 |
| spellingShingle | Taewoo Ha Inhee Park Kyung Ik Sim Howon Lee Jong-Sung Bae Su Jae Kim Jong Phil Kim Teun-Teun Kim Jae Hoon Kim Joon Ik Jang Se-Young Jeong Single-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperature APL Materials |
| title | Single-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperature |
| title_full | Single-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperature |
| title_fullStr | Single-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperature |
| title_full_unstemmed | Single-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperature |
| title_short | Single-crystalline Cu2O thin films of optical quality as obtained by the oxidation of single-crystal Cu thin films at low temperature |
| title_sort | single crystalline cu2o thin films of optical quality as obtained by the oxidation of single crystal cu thin films at low temperature |
| url | http://dx.doi.org/10.1063/1.5087114 |
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