毕业设计（论文）-氮化镓在铝酸镁钪表面生长初期的理论研究精选.doc

氮化镓在铝酸镁钪表面生长初期的理论研究 目录 摘要 I Abstract II 引言 1 第一章绪论 3 1.1氮化镓的性质 3 1.2 ScAlMgO4的性质 3 1.3薄膜生长初期的重要性 4 1.4计算机模拟计算 4 1.5研究意义 5 第二章理论基础与计算方法 6 2.1密度泛函理论在第一性原理计算中的应用 6 2.1.1 Hohenberg-Kohn定理 7 2.1.3自洽Kohn-Sham 方程 8 2.2密度泛函理论中的近似方法与赝势 9 2.3从头算（abinito）方法 10 第三章模拟计算与结果讨论 12 3.1计算方法及参数设置 12 3.2计算机模拟计算 12 3.3结果与讨论 13 3.3.1截断能与表面能 13 3.3.2吸附能与电子结构 16 3.3.3阴阳离子与极性 19 结论 20 致谢 21 参考文献 22 氮化镓在铝酸镁钪表面生长初期的理论研究 摘要:从头研究计算氮化镓晶格匹配的衬底在ScAlMgO4外延生长的初始阶段。ScAlMgO4表面的表面积的几何参数和电子结构已经通过密度泛函第一性原理研究。通过不同表面的表面能与松弛计算来检验不同的表面截断能的影响。与其他截断能相比O–Mg–O的截断能计算出的表面能更稳定，更适合做氮化镓的衬底。在本文的计算中，发现其能够作为适当的表面结构。在氮化镓外延生长初始阶段的基础上建立ScAlMgO4原子的吸附和扩散来对ScAlMgO4（0001）氮化镓 关键词：氮化镓；铝酸镁钪； 极性；第一原理  Theoretical study on the initial growth of gallium nitride on the surface of magnesium scandium oxide Abstract: The initial stages of GaN epitaxial growth on lattice-matched ScAlMgO4 substrates have been investigated by ab initio calculation. The geometrical parameters and electronic structure of ScAlMgO4 bulk and surface have been investigated by density-functional first-principles study. The effects of different surface terminations have been examined through surface energy and relaxation calculations. The O–Mg–O termination is more favorable than other terminations by comparing the calculated surface energies. It should be accepted as the appropriate surface structure in subsequent calculation. The initial stages of GaN epitaxial growths are discussed based on the adsorption and diffusion of the adatoms on reconstructed ScAlMgO4 (0001) surface. According to theoretical characterizations, Na adatom on the surface is more stable than GaN adatom is more favorable. These observations lead to the formation of GaN epilayer and explain experimentally-confirmed in-plane alignment mechanisms of GaN on ScAlMgO4substrates. Furthermore, the polarity of GaN surfaces on ScAlMgO4 (0001) at the initial growth stage have been explored by ab initio calculation. Theoretical studies indicate that the predominant growths of Ga-polar GaN are determi