| CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES |
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Structural and Electrical Properties of Single Crystalline a-Doped ZnO Thin Films Grown by Molecular Beam Epitaxy |
| LU Zhong-Lin1,2,3, ZOU Wen-Qin3, XU Ming-Xiang1, ZHANG Feng-Ming3, DU You-Wei3 |
| 1Department of Physics, Southeast University, Nanjing 2100962Department of Physics and Institute of Innovations and Advanced Studies (IIAS), National Cheng Kung University, Tainan 7013Jiangsu Provincial Laboratory for Nanotechnology, National Laboratory of Solid State Microstructure, and Department of Physics, Nanjing University, Nanjing 210093 |
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| Cite this article: |
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LU Zhong-Lin, ZOU Wen-Qin, XU Ming-Xiang et al 2009 Chin. Phys. Lett. 26 116102 |
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Abstract High-quality Ga-doped ZnO (ZnO:Ga) single crystalline films with various Ga concentrations are grown on a-plane sapphire substrates using molecular-beam epitaxy. The site configuration of doped Ga atoms is studied by means of x-ray absorption spectroscopy. It is found that nearly all Ga can substitute into ZnO lattice as electrically active donors, a generating high density of free carriers with about one electron per Ga dopant when the Ga concentration is no more than 2%. However, further increasing the Ga doping concentration leads to a decrease of the conductivity due to partial segregation of Ga atoms to the minor phase of the spinel ZnGa2O4 or other intermediate phase. It seems that the maximum solubility of Ga in the ZnO single crystalline film is about 2at.% and the lowest resistivity can reach 1.92×10-4Ω・cm at room temperature, close to the best value reported. In contrast to ZnO:Ga thin film with 1% or 2% Ga doping, the film with 4% Ga doping exhibits a metal semiconductor transition at 80K. The scattering mechanism of conducting electrons in single crystalline ZnO:Ga thin film is discussed.
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| Keywords:
61.72.Sd
72.20.Jv
73.50.-h
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Received: 05 August 2009
Published: 30 October 2009
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| PACS: |
61.72.sd
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(Impurity concentration)
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72.20.Jv
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(Charge carriers: generation, recombination, lifetime, and trapping)
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73.50.-h
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(Electronic transport phenomena in thin films)
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