共查询到18条相似文献,搜索用时 140 毫秒
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InAs量子环中类氢杂质能级 总被引:1,自引:0,他引:1
在有效质量近似下,利用微扰法研究了InAs量子环内类氢杂质基态及低激发态的能级分布。受限势采用抛物形势,在二维平面极坐标下,用薛定谔方程的精确解析解进行计算。数值计算结果显示,电子能级敏感地依赖于量子环半径,能级存在极小值,这是由于限制势采用抛物势的结果。如果减小环的半径,可以增加能级间距。第一激发态类氢杂质能级的简并没有消除,n≥2时简并的能级发生分裂并且间距随半径的增大而增大。电子能级间距还敏感地依赖于角频率并随角频率的增大而增大。第一激发态的简并没有消除,第二激发态的简并被部分地消除。在计算InAs量子环中类氢杂质的基态和低激发态的能级时,角频率改变的影响也是很深刻的。文章结果对研究量子环的光跃迁及光谱结构有重要指导意义。 相似文献
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无限深势阱下杂质量子点的能级计算 总被引:1,自引:0,他引:1
在有效质量近似下,垂直方向采用无限深势阱限制势,在x-y平面上,量子点内采用抛物势近似,在量子点边界处采用与实际情况更接近的无限深势阱.在中心杂质电荷为ηe时,利用波函数近似,得到基态和低激发态的能级,与x-y平面均采用抛物势时得到的能级进行了比较.计算发现在量子点真实半径比较小时,电子的基态和低激发态受其影响很大,而相应的能级随量子点的半径逐步增大.在量子点半径大于5倍有效玻尔半径时,能级受其影响已经变得很弱.并且,随着磁场的变化,量子点半径对基态和第一激发态的能级差的影响也很大.最后我们计算了杂质电子的基态束缚能并讨论了声子对其影响. 相似文献
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氮化物抛物量子阱中类氢杂质态能量 总被引:6,自引:1,他引:5
采用变分方法研究氮化物抛物量子阱(GaN/AlxGa1-xN)材料中类氢杂质态的能级,给出基态能量、第一激发态能量、结合能和跃迁能量等物理量随抛物量子阱宽度变化的函数关系.研究结果表明,基态能量、第一激发态能量、基态结合能和1s→2p±跃迁能量随着阱宽L的增大而减小,最后接近于GaN中3D值.GaN/Al0.3Ga0.7N抛物量子阱对杂质态的束缚程度比GaAs/Al0.3Ga0.7As抛物量子阱强,因此,在GaN/Al0.3-Ga0.7N抛物量子阱中束缚于杂质中心处的电子比在GaAs/Al0.3Ga0.7As抛物量子阱中束缚于杂质中心处的电子稳定. 相似文献
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考虑应变,在有效质量、有限高势垒近似下,变分研究了纤锌矿GaN/AlxGa1 -xN柱形量子点中类氢施主杂质态结合能随流体静压力、杂质位置及量子点结构参数(量子点高度、半径、Al含量)的变化关系.结果表明,类氢施主杂质态结合能随流体静压力增大而增大,且在量子点尺寸较小时,流体静压力对杂质态结合能的影响更为显著.受流体静压力的影响,杂质态结合能随量子点高度、半径的增加而单调减少,且变化趋势加剧;随Al含量增加而增大的趋势变缓.无论是否施加流体静压力,随着类氢施主杂质从量子点左界面沿材料生长方向移至右界面,杂质态结合能在量子点的右半部分存在一极大值.流体静压力使得极大值点向量子点中心偏移. 相似文献
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由于量子环特殊的结构,我们尝试过不少方法,发现一般传统方法很难求解薛定谔方程,故很难求出它的波函数和能级。国内外很多学者从事这方面的研究,但发表的文献非常少。有必要寻找一些新的方法从事这方面的研究工作,本文中采用了B样条函数近似拟合波函数的方法,计算了一个在谐振子束缚势和磁场作用下含有杂质的二维量子环中的电子能级。研究了电子能级随磁场强度、束缚势的变化关系以及电子能级与量子环半径的关系。我们发现电子能级随磁场强度、束缚势强度的增强而增强;每一个能级都有一个最小值在特定的量子环半径上,并且随着能级的增加,最小值的位置向半径大的方向偏移。 相似文献
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考虑应变,在有效质量、有限高势垒近似下,变分研究了纤锌矿GaN/AlxGa1-xN柱形量子点中类氢施主杂质态结合能随流体静压力、杂质位置及量子点结构参数(量子点高度、半径、Al含量)的变化关系.结果表明,类氢施主杂质态结合能随流体静压力增大而增大,且在量子点尺寸较小时,流体静压力对杂质态结合能的影响更为显著.受流体静压力的影响,杂质态结合能随量子点高度、半径的增加而单调减少,且变化趋势加剧;随A1含量增加而增大的趋势变缓.无论是否施加流体静压力,随着类氢施主杂质从量子点左界面沿材料生长方向移至右界面,杂质态结合能在量子点的右半部分存在一极大值.流体静压力使得极大值点向量子点中心偏移. 相似文献
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考虑应变,在有效质量、有限高势垒近似下,变分研究了纤锌矿GaN/AlxGa1-xN柱形量子点中类氢施主杂质态结合能随流体静压力、杂质位置及量子点结构参数(量子点高度、半径、Al含量)的变化关系.结果表明,类氢施主杂质态结合能随流体静压力增大而增大,且在量子点尺寸较小时,流体静压力对杂质态结合能的影响更为显著.受流体静压力的影响,杂质态结合能随量子点高度、半径的增加而单调减少,且变化趋势加剧;随Al含量增加而增大的趋势变缓.无论是否施加流体静压力,随着类氢施主杂质从量子点左界面沿材料生长方向移至右界面,杂质态结合能在量子点的右半部分存在一极大值.流体静压力使得极大值点向量子点中心偏移. 相似文献
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The energy levels and binding energies of a hydrogenic impurity in GaAs spherical quantum dots with radius R are calculated by the finite difference method. The system is assumed to have an infinite confining potential well with radius R, which can be viewed as a hard wall boundary condition. The parabolicity of the conduction band profile for GaAs material can be viewed as a parabolic potential well. The energy levels and binding energies are depended dramatically on the radius of the quantum dot and the parabolic potential well. The results show that parabolic potential can remarkably alter the energy level ordering and binding energy level ordering of hydrogenic impurity states for the quantum dot with a smaller radius R. 相似文献
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量子点作为一种重要的低维纳米结构, 近年来在单光子光源和新型量子点单光子探测器的研究引起了人们的广泛关注, 对各种势阱中量子点性质的研究已取得了重要成果. 但是大多理论研究都局限于无限深势阱, 而有限深势阱更具有实际意义. 利用平面波展开、幺正变换和变分相结合的方法研究了有限深势阱中极化子激发态能量及激发能随势阱形状和量子盘大小的变化规律. 数值计算结果表明: 极化子的激发态能量、激发能随势垒高度或宽度的增大而增大, 原因是势垒愈高、愈宽, 电子穿透势垒的可能性愈小, 电子在阱内运动的可能性愈大, 进而导致极化子的激发态能量和激发能均随势垒高度和宽度的增大而增大; 极化子的激发态能量和激发能随量子盘半径的增大而减小, 表明量子盘具有显著的量子尺寸效应; 极化子的激发态能量随有效受限长度的增加而减小, 原因是有效受限长度愈大, 有效受限强度愈小, 电子受到的束缚愈弱、振动愈慢、势能愈小, 进而导致基态能量、激发态能量减小; 同时由于激发态能量较基态能量减小慢, 使得激发能随之增加. 研究结果对量子点的应用具有一定的理论指导意义. 相似文献
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采用线性组合算符和幺正变换方法研究了磁场和库仑场对抛物量子点中极化子激发态性质的影响。导出了抛物量子点中弱耦合束缚磁极化子的振动频率、第一内部激发态能量、激发能量与量子点的有效受限长度、库仑束缚势和磁场的回旋频率之间的变化关系。通过数值计算,结果表明:抛物量子点中弱耦合束缚极化子的振动频率、第一内部激发态能量、激发能量均随量子点的有效受限长度减小而迅速增大。随库仑束缚势增大而增大。随磁场的回旋频率的增加而增大。 相似文献
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We report a detailed theoretical study of the effect of combined electric and magnetic field on the nonlinear optical rectification of a hydrogenic impurity, confined in a two dimensional disk-like quantum dot, with parabolic confinement potential. We use the compact density matrix formalism and iterative method to obtain nonlinear optical rectification and absorption coefficients. To find energy levels and wave functions, we employ exact diagonalization method in the effective mass approximation. As main result, we found that the transition energy from ground to first excited state redshifts with increasing the magnetic field while blueshifts for transition from ground to second excited state, moreover, for former transition, nonlinear optical rectification coefficient decreases with increasing magnetic field in contrast to that occurs for latter one. 相似文献
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The binding energy and diamagnetic susceptibility of an on-center hydrogenic donor impurity in an InAs spherical quantum dot placed at the center of a GaAs cylindrical nano-wire have been investigated using finite element method in the framework of the effective mass approximation. The binding energy and diamagnetic susceptibility are calculated as a function of the dot radius, nano-wire radius and nano-wire height. The results show that as the dot radius increases (I) for a dot radius smaller than some critical value, the effect of the spherical confinement on the energy levels becomes negligible and the energies remain constant, for a dot radius larger than some specific value, the energy levels decrease (II) the ground and the first excited state binding energies increase, reach a maximum and then decrease (III) the ground state diamagnetic susceptibility increases, reach a maximum and then decreases (IV) the first excited state diamagnetic susceptibility increases, indicating two maxima and then decreases. The effects of the nano-wire dimensions on the binding energy and diamagnetic susceptibility have also been studied. We found that the binding energy and diamagnetic susceptibility decrease reach a minimum value and then increase as the nano-wire radius increases. Finally we found that as the height of the nano-wire increases the ground state binding energy decreases, reaches a minimum value and then increases but the first excited state binding energy decreases and reaches a constant value. 相似文献
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Shi-Hua Chen 《Physica B: Condensed Matter》2011,406(10):2033-2037
A variational approach is employed to obtain the ground and the first excited state binding energies of an electron bound to a hydrogenic impurity in a polar semiconductor quantum dot (QD) with symmetric parabolic confinement in both two and three-dimensions. We perform calculations for the entire range of the electron-phonon coupling constant and the Coulomb binding parameter and for arbitrary confinement length. It is found that the binding energy of ground and first excited state is larger in a two-dimension (2D) dot than in a three-dimension (3D) dot and this trend is more pronounced with the increase of the electron-phonon coupling constant for the same value of the Coulomb binding parameter and confinement length. Furthermore, the ground and the first excited state binding energy increases with increasing the Coulomb binding parameter in both 2D and 3D QDs for the same electron-phonon coupling constant. 相似文献