Epitaxial Growth of ZnO Films on Patterned c-Plane GaN Layer Using Hydrothermal Method. (1st January 2015)

• Record Type: Journal Article
• Authors: Ko, Rong-Ming; Lin, Yan-Ru; Wang, Shui-Jinn; Su, Si-Ming; Huang, Yen-Chieh; Yu, Tsung-Hsien
• Is Part Of: ECS journal of solid state science and technology. Volume 4:Number 9(2015)
• Page Start: N111
• Page End: N116
• Publication Date: 2015-01-01
• Subjects: Solid state chemistry -- Periodicals; Electronics -- Materials -- Periodicals; Electrochemistry -- Periodicals; 541.0421
• DOI: 10.1149/2.0131509jss
• Languages: English
• ISSNs: 2162-8777

Abstract

Abstract : The growth of epitaxial ZnO film with a c -axis orientation on a patterned GaN/sapphire substrate using a two-step hydrothermal (HT) process is demonstrated. Honeycomb arrays of etched holes were formed on the GaN epilayer to unveil m -plane for the synthesis of ZnO crystallites with a lattice mismatch of 0.4% along c -axis (as compared with that of 1.88% on the c -plane). Effects of the etched pattern and HT processing parameters on the coalescence of hexagonal ZnO prisms are investigated. Experimental results reveal that etched holes with a 5-μm diameter, 3-μm spacing, and an off angle of 30° between the close-packing direction of the honeycomb array and the a -axis (i.e., the [ 11 2 ̄ 0 ] direction) of GaN yield ZnO films might be most efficient for the ZnO epitaxy. The successful growth of ZnO single-crystalline films can be attributed to the m -plane of GaN providing nucleation sites with a lower lattice mismatch for the hetero-epitaxy of ZnO crystallites and the propagation of homo-epitaxial lateral growth over c - and m -plane. Material analysis results confirm that the continuous ZnO films grown on the GaN epilayer have high quality and a single-crystalline wurtzite structure, suggesting a high potential for use in the fabrication of ZnO substrates and devices.