Studying the Strain/Stress of Zinc Oxide by X-ray Diffraction and Quantum Monte Carlo Methods

• Main Authors: Liu, Li-Hao, 劉力豪
• Other Authors: Lin, Chiung-Yuan
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/37180779891884548858

碩士 === 國立交通大學 === 工學院加速器光源科技與應用碩士學位學程 === 103 === In recent years, the Zinc Oxide material has drawn broad attentions and has been widely used in the semiconductors (like the Light-Emitting Diodes, the Surface Acoustic Wave devices and the other optoelectronic devices), medical (dental restoration and sun protection products) and conventional industries (rubber manufacturing industry and the cement industry and etc. ).We use a pulsed laser deposition system to grow high-quality epitaxial zinc-oxide thin film on different substrates, e.g. sapphire or silicon, where the later requires buffer layers like Al2O3 or Y2O3. In this thesis, we mainly focus on studying the modulus of elasticity and the physical properties of Zinc Oxide. There are two main parts in this study: (1) XRD experiments, using the synchrotron radiation (hard x-ray diffraction) to measure the uniaxial strains of Zinc Oxide and calculate the internal stress. (2) density-functional calculations with exchange correlation functionals treated by LDA, GGA, and hybrid functionals, where hybrid functionals used here include PBE0, and B3LYP. These hybrid functionals improve the calculated strains. (3) In addition, we also use the Quantum Monte Carlo method to calculate the strains, the bulk modulus and the Poisson’s ratio. According to the final results: (1)the density-functional calculations do not give qualitatively correct strains (the calculated tensile is the opposite of the experimental measurement). (2) Quantum Monte Carlo obtains the strains, including the bulk modulus, consistent with the experimental data.