Effects Of Annealing Temperature On Structural And Nanomechanical Characteristics Of Ga-Doped ZnO Thin Films

• Main Authors: Wang, Szuko, 王斯可
• Other Authors: Jian, Shengrui
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/63217503613452732992

博士 === 義守大學 === 材料科學與工程學系 === 100 === In this study, the effects of post-annealing（PA）and rapid thermal annealing（RTA）on the nano-structure, the surface morphology and nano-mechanical properties of ZnO thin films doped with a nominal concentration of 3 at.% Ga（ZnO:Ga）are investigated using X-ray diffraction（XRD）, atomic force microscopy（AFM）, scanning electron microscopy（SEM）and nano-indentation techniques. The Ga-doped ZnO thin films were deposited on the glass substrates at room temperature by radio frequency（RF）magnetron sputtering. The deformation behavior is referred to the inverse Hall‐Petch effect commonly observed in systems deformed primarily via grain boundary sliding. The suppression of dislocation movement‐associated deformation mechanism might be arisen from strong pinning effects introduced by Ga‐doping. Results revealed that the as-deposited GZO thin films were polycrystalline albeit the low deposition temperature. Post-annealing carried out at 300℃, 400℃ and 500℃ for one hour, respectively, which has resulted in progressive increase in both the average grain size and the surface roughness of the GZO thin film, in addition to the improved thin films crystallinity. Moreover, the hardness and Young’s modulus of GZO thin films are measured by a Berkovich nano-indenter operated with the continuous contact stiffness measurements（CSM）option. The hardness and Young’s modulus of GZO thin films increased as the annealing temperature increased from 300℃ to 500℃, with the best results being obtained at 500℃. According to the above better isothermal annealing condition at 500℃, the structural and nano-mechanical properties of Ga‐doped ZnO（GZO）thin films on glass substrates followed by rapid thermal annealing（RTA）process during 0.5min., 1.0min., 2.0min. and 3.0min., which were investigated by X‐ray diffraction（XRD）, atomic force microscopy（AFM）and nano-indentation techniques. The XRD results indicated that the annealed GZO thin films are textured, having a preferential crystallographic orientation along the hexagonal wurtzite（002）axis. Both the grain size and surface roughness of the annealed GZO thin films exhibit an increasing trend after RTA treatment. The hardness and Young’s modulus of the annealed GZO thin films were measured by a Berkovich nano-indenter operated with the continuous contact stiffness measurements（CSM）option. Furthermore, the hardness and Young’s modulus were found to increase with increasing grain size when the RTA time was prolonged from 0.5 min. to 3 min.