半导体量子点中的非线性光整流效应

发布时间：2018-05-30 04:37

本文选题：非线性光学 + 低维半导体材料　；参考：《内蒙古大学》2017年博士论文

【摘要】：非线性光学是现代光学领域十分重要的一个分支,它是自激光出现以后而发展起来的一门重要学科.随着研究的日趋成熟,非线性光学在光纤通信、光计算、光谱技术、激光技术以及物质结构分析等方面具有重要的应用价值,同时也促进了其他科学领域的发展.由于理想的非线性光学材料要求其具有较快的响应速度、较大的非线性极化率以及较小的阈值功率,而大量的科学研究证明,人工合成的低维半导体材料正符合上述要求.在低维半导体材料中,由于量子局域效应的存在,使得其非线性光学效应更加明显.因此,研究低维半导体材料中的非线性光学性质具有十分重要的意义.本文针对Ⅲ-Ⅴ族及Ⅱ-Ⅵ族低维半导体材料在非线性光学性质方面所体现出的特性,首先在有效质量近似下利用变分法研究了外电场下闪锌矿结构GaN/AlxGa1-xN椭球形量子点中的非线性光整流效应.其次,我们研究了外电场下球形量子点中极化子对非线性光整流效应的影响,考虑了局域光学声子和界面光学声子分别与电子和杂质的相互作用.最后,研究了外电场下球形量子点中激子的非线性光整流效应.数值计算结果表明,由于量子局域效应的存在,在椭球形量子点中可以获得很明显的光整流效应.椭球形状、量子点尺寸、外加电场、A1组分等对光整流效应有着十分重要的作用.椭球常数的增加会使光整流系数峰值减小且峰值位置向光子能量小的方向移动.即相对于扁平形椭球量子点,扁长形椭球量子点使光整流系数峰值减小并向光子能量小的方向移动.另外,外电场强度和量子点尺寸的增加使光整流系数峰值增加并向光子能量小的方向移动.相对于扁平形椭球量子点,电场对扁长椭球量子点中的光整流效应作用更加明显.此外,我们还发现随着A1组分的增加,光整流系数峰值单调递减,而峰值位置向光子能量大的方向移动.其次,考虑了局域光学声子和界面光学声子分别与电子和杂质的相互作用,通过对外电场下Zn1-xCdxSe/ZnSe球形量子点中极化子对非线性光整流效应的影响研究发现,极化子对光整流效应有着十分明显的影响.计算结果表明,在考虑极化子效应后,光整流系数峰值明显高于未考虑极化子效应的情形,且光整流系数峰值产生红移现象,尤其当量子点尺寸或Cd组分较小时,产生的红移更为明显.另外,无论是否考虑极化子效应,量子点尺寸以及电场强度的增加会使光整流系数峰值增加并向光子能量小的方向移动.随着Cd组分的增加,光整流系数峰值减小并向光子能量大的方向移动.此外,考虑极化子效应与未考虑极化子效应两种情形下的光整流系数峰值差随着电场强度的增加而增加,而随Cd组分的增加而减小.另一方面,不同的光学声子模式对光整流效应影响不同,相比于局域声子,界面声子对光整流效应产生的影响更为明显.最后,通过对外电场下GaAs/AlxGa1-xAs球形量子点中激子非线性光整流效应的研究,发现在考虑激子效应后,光整流系数峰值明显高于单电子态情形,而峰值位置没有发生改变.考虑库仑作用使激子光整流系数峰值增加并向光子能量高的方向移动.另外,随着电场强度的增加,光整流系数峰值先增加后减小,且峰值位置向光子能量低的方向移动.随着量子点尺寸的增加,光整流系数峰值增加并向光子能量小的方向移动.在考虑激子效应后,随着A1组分的增加,光整流系数峰值先增加后减小,而峰值位置向光子能量高的方向移动.
[Abstract]:Nonlinear optics is a very important branch of modern optics. It is an important subject developed after the emergence of laser. With the development of research, nonlinear optics has important application value in optical fiber communication, optical computing, spectral technology, laser technology and material structure analysis. As the ideal nonlinear optical materials require them to have faster response speed, larger nonlinear polarizability and smaller threshold power, a large number of scientific studies have proved that synthetic low dimensional semiconductor materials are in line with the above requirements. In the low dimensional semiconductor materials, the quantum local effect is due to the quantum local effect. It is of great significance to study the nonlinear optical properties of low dimensional semiconductor materials. In this paper, the characteristics of the nonlinear optical properties of the low dimensional semiconductor materials of the III - V and the II - VI family are presented in this paper. First, the variational method is used in the effective mass approximation. The nonlinear optical rectification effect in the GaN/AlxGa1-xN ellipsoidal quantum dots of the sphalerite structure under external electric field is studied. Secondly, we study the influence of the polaron in the spherical quantum dots on the nonlinear optical rectifying effect under the external electric field, and consider the interaction between the local optical phonon and the optical phonon of the interface with the electron and impurity. Finally, the study is made. The nonlinear optical rectifying effect of the exciton in a spherical quantum dot under an external electric field is obtained. The numerical results show that, due to the existence of the quantum local effect, a very obvious optical rectifying effect can be obtained in the ellipsoidal quantum dots. The shape of the ellipsoid, the size of the quantum dots, the applied electric field, and the A1 group are very important to the optical rectifying effect. The increase of the number will reduce the peak of the optical rectifying coefficient and move the peak position to the photon energy. That is, the flat long ellipsoid quantum dot reduces the peak of the light rectifying coefficient and moves to the direction of the photon energy. In addition, the increase of the external electric field intensity and the size of the quantum dot point increases the peak of the optical rectifying coefficient. The effect of the electric field on the light rectification effect in the flat ellipsoidal quantum dots is more obvious than that of the flat ellipsoidal quantum dots. Furthermore, we also find that the peak value of the optical rectifying coefficient decreases monotonically with the increase of the A1 component, and the peak position moves towards the light energy. Secondly, the local light is considered. The study of the interaction between the phonons and the optical phonons of the interface with the electrons and impurities respectively. Through the study of the influence of the polaron in the Zn1-xCdxSe/ZnSe spherical quantum dots on the nonlinear optical rectifying effect under the external electric field, it is found that the polaron has a very obvious effect on the optical rectifying effect. The peak value is obviously higher than that without the polaron effect, and the peak of the optical rectifying coefficient is red shift, especially when the size of the quantum dots or the Cd component is small, the red shift is more obvious. In addition, the increase in the quantum point size and the intensity of the electric field will increase the peak of the optical rectifying coefficient and to the photon energy. With the increase of the Cd component, the peak value of the optical rectifying coefficient decreases and moves to the direction of the photon energy. In addition, the peak difference of the optical rectifying coefficient under the polaron effect and the non considered polaron effect increases with the increase of the electric field intensity, but decreases with the increase of the Cd component. On the other hand, the difference is different. The effect of optical phonon mode on the optical rectification effect is different, compared with the local phonon, the influence of the interfacial phonon on the optical rectifying effect is more obvious. Finally, through the study of the exciton nonlinear optical rectification effect of the exciton in the GaAs/AlxGa1-xAs spherical quantum dots under the external electric field, it is found that the peak value of the optical rectifying coefficient is obviously higher than that after the exciton effect is considered. The peak position is not changed in the electronic state. The Coulomb effect makes the peak of the exciton light rectifying coefficient increase and move to the direction of high photon energy. In addition, with the increase of the intensity of the electric field, the peak value of the optical rectifying coefficient increases first and then decreases, and the peak position moves to the direction of low photon energy. With the increase of quantum dots, light is increased. The peak value of the rectifying coefficient increases and moves in the direction of the photon energy. After the exciton effect is considered, with the increase of the A1 component, the peak of the optical rectifying coefficient first increases and then decreases, while the peak position moves toward the direction of the photon energy.
【学位授予单位】：内蒙古大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O471.1

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