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.doc

氮化镓在铝酸镁钪表面生长初期的理论研究目录摘要 ......................................................................................................................................IAbstract .............................................................................................................................II引言 .....................................................................................................................................1第一章绪论 .....................................................................................................................31.1 氮化镓的性质 ..........................................................................................31.2 ScAlMgO4 的性质 ...................................................................................31.3 薄膜生长初期的重要性 ..........................................................................41.4 计算机模拟计算 ......................................................................................41.5 研究意义 ..................................................................................................5第二章理论基础与计算方法 ......................................................................62.1 密度泛函理论在第一性原理计算中的应用 ..........................................62.1.1 Hohenberg-Kohn 定理 ..........................................................................72.1.3 自洽 Kohn-Sham 方程 .........................................................................82.2 密度泛函理论中的近似方法与赝势 ......................................................92.3 从头算（abinito）方法 .........................................................................10第三章模拟计算与结果讨论 .............................................................................123.1 计算方法及参数设置 ............................................................................123.2 计算机模拟计算 ....................................................................................123.3 结果与讨论 ............................................................................................133.3.1 截断能与表面能 .................................................................................133.3.2 吸附能与电子结构 .............................................................................163.3.3 阴阳离子与极性 .................................................................................19结论 ..................................................................................................................................20致谢 ..................................................................................................................................21参考文献 ........................................................................................................................22I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）表面进行讨论根据理论研究，氮原子在表面吸附更稳定这些发现揭示了氮化镓外延层的生长方式,以及氮化镓与 ScAlMgO4 衬底间外延生长关系在此基础上进一步计算 ScAlMgO4（0001）上氮化镓表面极性发现，氮化镓初始生长阶段主要生长由氮极性结构组成关键词：氮化镓；铝酸镁钪； 极性；第一原理IITheoretical study on the initial growth of gallium nitride on the surface of magnesium scandium oxideAbstract: 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 determined by the initial growth stage.Key words ：GaN; ScAlMgO4; polarity; density-functional first-principles study 1引言随着现代科学技术的飞速发展，第三代半导体材料已经成为提升新一代信息技术核心竞争力的重要材料。

以硅，锗等元素半导 体为代表的第一代半导体材料，奠定了微电子产业发展基 础 [1]；以砷化镓，磷化铟为代表的第二代半导体材料，奠定了信息产业发展基础；以氮化镓为代表的第三代半导体材料，因具备禁带宽度大、击 穿电场高、热导率大、电子饱和漂移速率高、抗辐射能力强等优越性能，是固态光源和电力电子、微波射频器件的“核芯”，在半导体照明、新一代移动通信、能源互联网、高速轨道交通、新能源汽 车、消 费类电子等领域有广阔的应用前景，有望突破传统半导体技 术的瓶颈，与第一代、第二代半 导体技术互补，对节能减排、产业转型升级、催生新的经济增长点将发挥 重要作用 [2,3]目前，随着外延生长单晶薄膜技术越来越受到关注，宽禁带半导体材料由于其优越的性能和潜在的应用在电子和电子学中的潜在应用也成为研究热点而本文中我们主要对氮化镓膜进行理论研究氮化镓膜通常情况下都是通过异质外延在异质衬底上，例如在蓝宝石或尖晶石上制造，但是因为缺少大块晶体，导致了在外延层和异质衬。