Fabrication and Characterization of Zinc Oxide Produced by the Remote Plasma Oxidation of Thermal Evaporated Zinc

• Main Authors: Chih-hung Chen, 陳致宏
• Other Authors: Chao-sheng Chou
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/91223129276773153485

碩士 === 義守大學 === 材料科學與工程學系碩士班 === 96 === ZnO has been processed by remote plasma oxidation of thermal evaporated Zn on silicon substrate. Thermal evaporation deposition has the benefits of simplicity, low cost, capability to deposit large area thin films and the easy control of the film composition. Remote plasma oxidation can reduce the thermal budget, the ion barbardment and electrical charging on the films. The morphology, microstructure, photoluminescence and defect concentration of the ZnO were discussed by controlling factors including oxidation temperature and RF plasma power. Optical Emission Spectroscopy (OES), X-ray Diffration (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Photoluminescence Analysis (PL) were used to investigate the morphology, microstructure, chemical state, decfect, and photoluminescence of ZnO. XRD and TEM results showed that oxidation of thermal evaporated Zn were enhanced with increasing the oxidation temperature and remote plasma power. Meanwhile, ZnO could be formed by remote plasma oxidation even under 200 ℃. With increasing oxidation temperature and remote plasma power, the morphology of Zn/ZnO was transformed from coaxial Zn/ZnO rods at l00 ℃~200 ℃, to polycrystalline ZnO nanotube at 300 ℃~400 ℃. Grain size and c-lattice constant of ZnO increased with increasing oxidation temperature ranging from 0 ℃~400 ℃ and with increasing remote plasma power ranging from 0 W~200 W. TEM results showed that the epitaxial ZnO sheath grown on Zn core has an orientation relationship [010]Zn//[010]ZnO, and (002)Zn//(002)ZnO. PL analysis results indicated that ZnO emitted UV light, blue light, and green light emissions. The UV light emission was attributed to the two electronic transitions from the donor level of free exciton and Zn interstitial to valence band. The blueshit of UV light emission peak was possibly due to the concentration reduction of Zn interstitial defect. The blue light emission was attributed to the electronic transition from the donor level of Zn interstitial to acceptor level of Zn vacancy, and the green light emission was attributed to the electronic transition from the donor level of oxygen vacancy to acceptor level of valence band. The blue light emission intensity and the green light emission intensity showed a direct proportion relationship. With increasing oxidation temperature and remote plasma powder, both the blue light emission intensity and the green light emission intensity decreased, meanwhile, concentration of the ZnO defects, Vo and Zni, also decreased.