ZnO Heteroepitaxy on Sapphire Using a Novel Buffer Layer of Titanium Oxide: Crystallographic Behavior


A novel buffer layer consists of titanium oxide grown on a-sapphire by low-pressure chemical vapor deposition using titanum-tetra-iso-propoxide and oxygen gas was used for ZnO epitaxial growth at temperature as low as 340 by plasma-assisted epitaxy using radio-frequency oxygen-gas plasma. XRD and RHEED indicated (0001)Ti2O3 layer in corundum crystal system was epitaxially grown on the substrate in an in-plane relationship of [1-100]Ti2O3// [0001]Al2O3 by uniaxial phase-lock system. Growth behavior of ZnO layer was significantly dependent on the Ti2O3 buffer-layer thickness, for example, dense columnar ZnO-grains were grown on the buffer layer thinner than 10 nm but the hexagonal pyramid-like grains were formed on the thin buffer layers below 2 nm. RHEED observations showed ZnO layer including the pyramid-like grains was epitaxially grown with single-domain on the thin buffer layer of 0.8 nm in the in-plane relationship of [1-100]ZnO//[1-100]Ti2O3//[0001]Al2O3, whereas the multi-domain was included in ZnO layer on the buffer layer above 10 nm.

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S. Yamauchi and Y. Imai, "ZnO Heteroepitaxy on Sapphire Using a Novel Buffer Layer of Titanium Oxide: Crystallographic Behavior," Crystal Structure Theory and Applications, Vol. 2 No. 2, 2013, pp. 39-45. doi: 10.4236/csta.2013.22006.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] M. A. L. Johnson, et al., “MBE Growth and Properties of ZnO on Sapphire and SiC Substrates,” Journal of Electronic Materials, Vol. 25, No. 5, 1996, pp. 855-862. doi:10.1007/BF02666649
[2] A. B. M. A. Ashrafi, et al., “Nitrogen-Doped p-Type ZnO Layers Prepared with H2O Vapor-Assisted Metalorganic Molecular-Beam Epitaxy,” Japanese Journal of Applied Physics, Vol. 41, 2002, pp. L1281-L1284. doi:10.1143/JJAP.41.L1281
[3] R. D. Vispute, et al., “High Quality Crystalline ZnO Buffer Layers on Sapphire(001) by Pulsed Laser Deposition for III-V Nitrides,” Applied Physics Letters, Vol. 70, No. 20, 1997, pp. 2735-2737. doi:10.1063/1.119006
[4] S. Yamauchi, et al., “Low Temperature Epitaxial Growth of ZnO Layer by Plasma-Assisted Epitaxy,” Thin Solid Films, Vol. 345, No. 1, 1999, pp. 12-17. doi:10.1016/S0040-6090(99)00096-6
[5] S. Yamauchi, et al., “Plasma-Assisted Epitaxial Growth of ZnO Layer on Sapphire,” Journal of Crystal Growth, Vol. 214-215, 2000, pp. 63-67. doi:10.1016/S0022-0248(00)00060-9
[6] S. Yamauchi, et al., “Surface Treatment of Si Using Hydrogen-Plasma to Improve Optoelectronic Property of ZnO on (111)Si,” Japanese Journal of Applied Physics, Vol. 44, 2005, pp. 7801-7804. doi:10.1143/JJAP.44.7801
[7] K. Minegishi, et al., “Growth of p-Type Zinc Oxide Films by Chemical Vapor Deposition,” Japanese Journal of Applied Physics, Vol. 36, 1997, pp. L1453-L1455. doi:10.1143/JJAP.36.L1453
[8] M. Joseph, et al., “p-Type Electrical Conduction in ZnO Thin Films by Ga and N Codoping,” Japanese Journal of Applied Physics, Vol. 38, 2001, pp. L1205-L1207. doi:10.1143/JJAP.38.L1205
[9] D. C. Look, et al., “Characterization of Homoepitaxial p-Type ZnO Grown by Molecular Beam Epitaxy,” Applied Physics Letters, Vol. 81, No. 10, 2002, pp. 18301832. doi:10.1063/1.1504875
[10] S. Yamauchi, et al., “Photoluminescence Studies of Undoped and Nitrogen-Doped ZnO Layers Grown by Plasma-Assisted Epitaxy,” Journal of Crystal Growth, Vol. 260, No. 1-2, 2006, pp. 1-6. doi:10.1016/j.jcrysgro.2003.08.002
[11] I. S. Hauksson, et al., “Compensation Processes in Nitrogen Doped ZnSe,” Applied Physics Letters, Vol. 61, No. 18, 1992, pp. 2208-2210. doi:10.1063/1.108296
[12] A. Ohtomo, et al., “Lateral Grain Size and Electron Mobility in ZnO Epitaxial Films Grown on Sapphire Substrates,” Journal of Crystal Growth, Vol. 214-215, 2000, pp. 284-288. doi:10.1016/S0022-0248(00)00093-2
[13] Y. Chen, et al., “Layer-by-Layer Growth of ZnO Epilayer on Al2O3(0001) by Using a MgO Buffer Layer,” Applied Physics Letters, Vol. 76, No. 5, 2000, pp. 559-561. doi:10.1063/1.125817
[14] K. H. Ahna, et al., “Kinetic and Mechanistic Study on the Chemical Vapor Deposition of Titanium Dioxide Thin Films by in Situ FT-IR Using TTIP,” Surface and Coatings Technology, Vol. 171, No. 1-3, 2003, pp. 198-204. doi:10.1016/S0257-8972(03)00271-8
[15] S. Tokita, et al., “High-Rate Epitaxy of Anatase Films by Atmospheric Chemical Vapor Deposition,” Japanese Journal of Applied Physics, Vol. 39, 2000, pp. L169L171. doi:10.1143/JJAP.39.L169
[16] S. Weisssmann, et al., “Selected Powder Diffraction Data for Metals and Alloys,” JCPDS, Card No. 10-63, 1978, p. 298.
[17] K. Nakahara, et al., “Growth of Undoped ZnO Films with Improved Electrical Properties by Radical Source Molecular Beam Epitaxy,” Japanese Journal of Applied Physics, Vol. 40, 2001, pp. 250-254. doi:10.1143/JJAP.40.250
[18] T. Fukuda and H. J. Scheel, “Crystal Growth Technology,” Wiley, New York, 2003.
[19] I. Ohkubo, et al., “In-Plane and Polar Orientations of ZnO Thin Films Grown on Atomically Flat Sapphire,” Surface Science, Vol. 443, 1999, pp. L1043-L1048. doi:10.1016/S0039-6028(99)01024-9
[20] H. Kato, et al., “High-Quality ZnO Epilayers Grown on Zn-Face ZnO Substrates by Plasma-Assisted Molecular Beam Epitaxy,” Journal of Crystal Growth, Vol. 265, No. 3-4, 2004, pp. 375-381. doi:10.1016/j.jcrysgro.2004.02.021

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