【作者】 尚景智；

【导师】 张保平；

【作者基本信息】 厦门大学 ， 凝聚态物理， 2009， 硕士

【摘要】 Ⅲ族氮化物(GaN,AlN及InN)半导体材料具有优异的光学和电学特性,已引起人们广泛的关注和研究。特别是在任意组分下都具有直接带隙的AllnGaN四元材料在高效率短波长发光器件和电子器件领域有着广泛的应用前景,目前正逐渐成为继三元氮化物材料之后国际上新的研究热点。另一方面,GaN基垂直腔面发射激光器(VCSEL)一直是Ⅲ族氮化物器件研究的前沿课题,而高反射率氮化物分布布拉格反射镜(DBR)作为GaN基VCSEL的重要组成部分,其性能和结构也一直被改良和优化。本论文主要以AlInGaN材料的生长和GaN基DBR的制备两个方面为研究对象,详细研究了利用金属有机物化学气相沉积(MOCVD)方法在蓝宝石C面衬底上制备AlInGaN薄膜的生长条件和样品的表面、结构及光学性质,设计并制备了高反射率且表面平整的AlN/GaN DBR。具体的研究内容和相应结果有以下几个部分:1、研究了AlInGaN薄膜的MOCVD生长特性。重点研究了不同生长温度下AlInGaN材料表面形貌的变化及成因,实验上直接证明了不同厚度的AlInGaN薄膜内存在的组分拉伸现象(composition pulling effect)。发现反应室压强与AlInGaN材料组分及其均匀性有密切的关系。2、确认了低温AlN插入层对AlInGaN材料中应力和表面形貌的影响。3、分析了不同生长温度下AlInGaN薄膜的生长机制并提出了相关的生长模型,通过调整生长温度,成功制备出a轴品格匹配的AlInGaN/GaN异质外延结构。4、理论上模拟了折射率、周期数和各层厚度偏差对GaN基DBR结构反射特性的影响,为后续的GaN基DBR结构的生长和设计提供了理论指导和依据。生长了AlInGaN/GaN DBR结构,研究了生长温度和GaN缓冲层厚度对AlInGaN/GaN DBR表面和结构的影响。5、通过使用较薄的GaN缓沖层,低温AlN插入层和DBR中AlN层掺入In三种手段,利用MOCVD方法生长了具有高折射率差的AlN/GaN DBR,所制样品分别在蓝光和紫光波段达到99%的高反射率,并且表面较为平整。更多还原

【Abstract】 Ⅲ-nitrides(GaN,AlN and InN) have been attracting a great deal of attention and research due to their outstanding optical and electrical properties.All quaternary AlInGaN alloys with arbitrary element contents are direct optical bandgaps,which can be used in high efficiency light-emitting and electronic devices.Nowadays,quaternary AlInGaN alloys are becoming a new study hotspot after their ternary alloy systems. On the other hand,GaN-based vertical cavity surface emitting laser(VCSEL) is always the frontier topic ofⅢ-nitrides.Therefore, high-reflectivity distributed Bragg reflector(DBR),as an important component in VCSEL,has also been widely studied.In this paper,we focus on preparation and characterization of quaternary AlInGaN films and GaN-based DBRs grown on C-plane sapphire by metal organic chemical vapor deposition(MOCVD).The main results are summarized as follows:1.Growth characteristics of quaternary AlInGaN films are investigated in details.It is found that growth temperature has significant influence on the surface morphology.We confirm that the composition pulling effect occurs in AlInGaN films.We also observe strong dependence of composition in AlInGaN films on the reactor pressure.2.It is demonstrated that low temperature(LT) AlN insertion layer between GaN buffer layer and AlInGaN epilayer can affect strain distribution and improve the surface morphology.3.The growth mechanism of AlInGaN at different temperatures is studied.By controlling the growth temperature,a-plane lattice-matched AlInGaN/GaN heterostructure is obtained.4.Based on geometrical optics theory,the influence of refractive index,period number and thickness deviation on reflective spectra is simulated.AlInGaN/GaN DBRs are fabricated on GaN/Sapphire templates,and the influence of growth temperature and GaN buffer layer on the performance of DBR is investigated5.High reflectivity AlN/GaN DBRs are grown on GaN/sapphire templates by MOCVD.By controlling the thickness of GaN buffer layer,inserting LT-AlN layer and doping Indium during the growth of theλ/4 AlN layers, the magnitude of strain in DBR is reduced and the surface morphology of the sample is improved.The peak reflectivity of two DBRs attains to 99% in violet and blue regions,respectively.更多还原