Temperature-Dependent Photoluminescence of ZnO Thin Films Grown on Off-Axis SiC Substrates by APMOCVD |
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Authors: | Ivan Shtepliuk Volodymyr Khranovskyy Arsenii Ievtushenko Rositsa Yakimova |
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Institution: | 1.Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden; (V.K.); (R.Y.);2.Department of Physics and Technology of Photoelectronic and Magnetoactive Materials, I. Frantsevich Institute for Problems of Material Science, NASU, 3 Krzhizhanovskogo str., 03142 Kyiv, Ukraine; |
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Abstract: | The growth of high-quality ZnO layers with optical properties congruent to those of bulk ZnO is still a great challenge. Here, for the first time, we systematically study the morphology and optical properties of ZnO layers grown on SiC substrates with off-cut angles ranging from 0° to 8° by using the atmospheric pressure meta–organic chemical vapor deposition (APMOCVD) technique. Morphology analysis revealed that the formation of the ZnO films on vicinal surfaces with small off-axis angles (1.4°–3.5°) follows the mixed growth mode: from one side, ZnO nucleation still occurs on wide (0001) terraces, but from another side, step-flow growth becomes more apparent with the off-cut angle increasing. We show for the first time that the off-cut angle of 8° provides conditions for step-flow growth of ZnO, resulting in highly improved growth morphology, respectively structural quality. Temperature-dependent photoluminescence (PL) measurements showed a strong dependence of the excitonic emission on the off-cut angle. The dependences of peak parameters for bound exciton and free exciton emissions on temperature were analyzed. The present results provide a correlation between the structural and optical properties of ZnO on vicinal surfaces and can be utilized for controllable ZnO heteroepitaxy on SiC toward device-quality ZnO epitaxial layers with potential applications in nano-optoelectronics. |
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Keywords: | ZnO SiC off-cut angle luminescence APMOCVD |
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