【作者】 刘欢；

【导师】 袁小明；

【作者基本信息】 中南大学 ， 电子材料与器件， 2022， 硕士

【摘要】 Ⅲ-Ⅴ族纳米半导体阵列在光学、电学、光电子等领域都具有广泛的应用。自下而上外延生长的纳米结构可实现晶体结构的有效调控,实现稳定闪锌矿（ZB）及亚稳相纤锌矿（WZ）Ⅲ-Ⅴ族半导体的外延生长。选择性区域外延（SAE）生长亚稳相结构是调控半导体能带结构、光学和电学性质的有效手段之一。因此揭示不同晶体结构半导体的热力学及光学性质对开发半导体信息器件具有重要研究价值。ZB及WZ结构的磷化铟（In P）都是直接带隙半导体,具有高载流子迁移率以及很低的表面复合速度,在近红外光学及光电信息领域都具有重要应用,例如太阳能电池,光电探测器,激光等方面。本论文研究以In P为代表的Ⅲ-Ⅴ族化合物半导体的拉曼光谱及二次谐波（SHG）性质,取得的成果如下:（1）以WZ InP纳米片阵列为例,进行了详细的光学和拉曼散射研究。通过偏振依赖性拉曼实验说明了A₁（TO）和E_2h声子振动模式在偏振散射中呈现相反的趋势。通过温度依赖拉曼实验,认定Al₂O₃对873 K高温以下的纳米片具有良好的保护作用,使其没有出现明显的光学性能劣化或相变。同时也得到了WZ和ZB In P的一阶温度系数和热膨胀系数,它们的数值大小非常接近。此外,应用密度泛函理论（DFT）和密度泛函微扰理论（DFPT）,计算了WZ In P晶格的格律奈森（Grüneisen）参数和热膨胀系数,结果与实验数据吻合较好。结果证明WZ与ZB In P相的热力学性质接近。研究所获得的In P纳米片的热力学性质为那些在高温下工作的器件提供了有价值的信息。（2）针对ZB以及WZ InP纳米结构在非线性光学领域的应用,本文进行了SHG性质的研究。首先,通过第一性原理计算获得了ZB以及WZ In P的折射率和二阶非线性系数。在此基础上,结合COMSOL仿真软件探索了SHG的偏振效应与In P晶体结构及形貌的关系。结果表明可以利用形状工程、调节晶体结构以及控制偏振激发调控材料的SHG响应,在最大限度上增强SHG转换效率。同时探索了不同形貌及晶体结构对SHG辐射方向的调控,证明了通过控制In P纳米片的形貌以及晶体结构,可实现SHG的正向辐射,并且极大的增强了SHG的收集效率。研究成果为利用外延生长的WZ In P纳米结构阵列在基于SHG的偏振探测器、高效率器件以及光通信器件中的应用奠定了理论基础。图38幅,表2个,参考文献213篇更多还原

【Abstract】 Ⅲ-Ⅴ nano-semiconductor arrays have been widely used in optical,electrical and photoelectronic applications.Bottom-up epitaxy of nanostructures is an effective approach to modify their crystal structures and realize the epitaxy of stable zinc blende（ZB）and metastable wurtzite（WZ）Ⅲ-Ⅴ semiconductor.Metastable phase fabricated by selective area epitaxy（SAE）is regarded as one of effective methods of modulating semiconductor band structure and their optical and thermal properties.Therefore,to develop semiconductor information devices,it has significant research value to reveal optical and thermal properties of semiconductors with different crystal structures.Indium Phosphide（In P）either with ZB or WZ structures is a direct band gap semiconductor material with high carrier mobility and low surface recombination speed,which has potential application among near-infrared（near-IR）optics and photoelectric information,such as solar cells,light-emitting devices,photodetectors,and higher speed electron lasers.In this paper,the Raman spectra and second harmonic properties of Ⅲ-Ⅴ compound semiconductors represented by In P are studied.The results achieved are as follows:（1）Here,we take WZ InP nanosheet arrays as an example and perform detailed optical and Raman scattering studies.The opposite trends of A₁（TO）and E_2hmodes are shown in polarization-dependent Raman scattering.It is shown in temperature-dependent Raman scattering that Al₂O₃provides good protection for nanosheets under the environment with temperature below 873 K,with no observable deterioration in optical properties or phase transition.The first-order temperature coefficient and thermal expansion coefficient of WZ and ZB In P could also be obtained from temperature-dependent Raman experiments which are quite close to each other.Furthermore,by applying density functional theory and density functional perturbation theory,the Grüneisen parameter and the thermal expansion coefficient of WZ In P lattice are calculated,showing good agreement with the experimental Raman data.The difference between WZ and ZB In P phase is negligible in thermodynamic property.The revealed thermal properties of the In P nanosheets provide valuable information for those devices that operate at high temperatures.（2）Aiming at the application of ZB and WZ InP nanostructures in nonlinear optics,the properties of SHG are studied in this paper.Firstly,the refractive index and second-order nonlinear coefficients of ZB and WZ In P are obtained by first-principles calculation.On this basis,the relationship between SHG polarization effect and In P crystal structure and morphology was explored with COMSOL simulation software.The results show that the SHG conversion efficiency can be maximized by shape engineering,crystal structure and polarization excitation to regulate the SHG response.At the same time,the regulation of SHG radiation direction by different morphology and crystal structure was explored,and it was proved that forward radiation of SHG could be realized by controlling the morphology and crystal structure of In P nanosheets,and the collection efficiency of SHG was greatly enhanced.The research results lay a theoretical foundation for the application of WZ In P nanostructure arrays with epitaxial growth in SHG based polarization detectors,high efficiency devices and optical communication devices.更多还原