标题: | 以同步辐射X光绕射实验和量子蒙地卡罗方法来探讨氧化锌的应变及应力变化 Studying the Strain/Stress of Zinc Oxide by X-ray Diffraction and Quantum Monte Carlo Methods |
作者: | 刘力豪 Liu, Li-Hao 林炯源 徐嘉鸿 Lin, Chiung-Yuan Hsu, Chia-Hung 工学院加速器光源科技与应用硕士学位学程 |
关键字: | 量子蒙地卡罗;第一原理;同步辐射;氧化锌;弹性模量;应变;Quantum Monte Carlo;First Principle;Synchrotron Radiation;Zinc Oxide;Elastic Modulus;Strain |
公开日期: | 2015 |
摘要: | 近年来氧化锌材料已被广泛的讨论并且应用在半导体(发光二极体和表面声波元件等光电元件)、医学(牙齿修复和防晒相关产品)和传统产业(橡胶制造工业与水泥工业等传产)上。在本文中,我们利用脉冲雷射蒸镀系统在不同的基板上成长高品质的氧化锌磊晶薄膜,其中使用的基板包括蓝宝石基板与使用奈米厚度的氧化铝(Al2O3)或氧化钇(Y2O3)材料当作缓冲层的矽基板。 在本论文当中,我们主要着重在探讨氧化锌的弹性模量与其相关的物理性质,其中主要分成实验和模拟计算两部份来做研究:(1)利用同步辐射X光绕射来量测氧化锌的应变变化及其内部所受的应力数据。(2)模拟计算在密度泛函理论的架构下,保留LDA与GGA,之后并进一步超越密度泛函理论使用了混合函数近似的方式,如PBE0和B3LYP等混合函数计算方法,藉由其来改善计算应变趋势的误差,(3)此外我们也使用量子蒙地卡罗法来计算材料的应变变化、体积模量与帕松比。 根据研究结果显示:(1)密度泛函理论计算无法完整描述氧化锌的应变趋势,其应变的定性趋势并不正确(在拉伸的部份是跟实验值相反),(2)量子蒙地卡罗法的计算则使应变趋势与实验数据一致并使体积模量的计算更加精确。 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. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT079801504 http://hdl.handle.net/11536/127589 |
显示于类别: | Thesis |