Growth Behavior And The Optical Property Of ZnO Film Deposited By Reactive Magnetron Sputtering And Electrodeposition

ZnO is a direct band-gap semiconductor (Eg=3.3eV at RT) with a high exciton binding energy of about 60meV. The feasibility of using excitionic lasers of ZnO at RT has been demonstrated. Besides, ZnO thin films can be prepared at temperature lowerthan 600℃, its growth temperature is lower than GaN, SiC and other II -IVsemiconductor materials. Owing to these properties, ZnO can be used asroom temperature short wavelength ophotoelectron material. It has been investigated extensively because of its interesting electrical, optical and piezoelectric properties making suitable for many applications such as light emitting diodes, photodetectors, electroluminescence, transparent conductive film, surface acoustic waves device and so on. The renewed interest of ZnO film is fueled since room temoerature lasing was reported by Tang et al.In this thesis, the reactive radio-frequency(RF) magnetron sputtering and electrodeposition merhod are used to deposite ZnO films. This work is focus on the growth behavior and the optical properties of the ZnO films. The results are summarized as follow:1. A two-step growth method is used to prepare the ZnO films. It is found that different deposition time of the buffer layer results in the difference in the morphology of ZnO films. The variation of the ZnO films can be related to the coverage of the buffer layer. When the buffer layer cannot cover the substrate, the ZnO film has small grains similar to the film without buffer layer and quite large roughness and inner stress. When the substrate is covered by the buffer layer, a ZnO film can be obtained with large size of grains, smooth surface and low inner stress. The growth behavior of the ZnO films is also related to the etching time of Si chip. With the increase of the etching time, both the roughness of the ZnO films and the correlation length of the self-affine morphology decrease.2. ZnO thin films were electrodeposited on glasses coated with a transparent-conductive film (In₂O₃: Sn) in different currents. It is found that all the films show highly C-axis textured structure and the surface morphology is strongly current-dependent. The transmission spectra show that the films have a transmittance higher than 80% in the wavelength range of visible light. The films have an increase in thickness with the deposition current. The PL spectra exhibit two emission bands, an ultraviolet (UV) one from the exciton transition and a visible light one that might be from the defects in the films. The UV emission band has an obvious blueshift, which is assigned to be from In doping during the deposition. With the increase of deposition current, the UV emission decreases while the visible light emission goes up.