Interface Engineering in Heteroepitaxy |
| S.K. Hong, Y. Chen, H.J. Ko and T. Yao Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan |
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| We report the importance of interface engineering in heteroepitaxy with examples of plasma-assisted molecular beam epitaxial ZnO growths on (0001) sapphire substrates and on (0001) GaN/sapphire templates, whose interfaces are engineered to improve and to control properties of ZnO films. The growth of rocksalt structure MgO buffer on Al2O3 (0001) is developed for ZnO epitaxy. By employing the MgO buffer layer, the formation of 30° rotated mixed domains is prohibited and two-dimensional layer-by-layer growth of ZnO on sapphire substrate is achieved. High-resolution X-ray diffraction reveals the superior improvement in a crystal quality of ZnO films with an MgO buffer. Polarity of wurtzite structure ZnO films on Ga-polar GaN/sapphire templates is controlled by changing interface structures. By forming a single crystalline, monoclinic Ga2O3 interfacial layer between GaN and ZnO through O-plasma pre-exposure on the Ga-polar GaN surface, O-polar ZnO films are grown. By forming the ZnO/GaN heterointerface without an interfacial layer through the Zn pre-exposure on the Ga-polar GaN surface, Zn-polar ZnO films are grown. |
| DOI: 10.12693/APhysPolA.102.541 PACS numbers: 68.35.--p, 68.35.Dv, 81.15.--z, 81.15.Hi, 81.10.Aj |