Atomistic theoretical study of electronic and polarization properties of single and vertically stacked elliptical InAs quantum dots
Atomistic theoretical study of electronic and polarization properties of single and vertically stacked elliptical InAs quantum dots
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单层和垂直堆叠椭圆InAs量子点电子和偏振特性的原子理论研究
DOI：
10.1103/physrevb.86.155444
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发表时间：
2012
影响因子：
3.7
通讯作者：
M. Usman
中科院分区：
文献类型：
--
作者：
M. Usman
半导体量子点（QD）的各向同性偏振响应的演示是设计几种光电技术的关键一步。在影响量子点偏振度的诸多参数中，形状不对称性是一个关键因素。我们进行了数百万原子的模拟，研究了椭圆形状对单个和垂直堆叠的InAs量子点的电子和偏振特性的影响。低纵横比（AR）和高AR QD之间的比较表明，电子和偏振特性强烈依赖于QD的AR;高QD的伸长允许在更宽的范围内调谐DOP。然后，我们将我们的分析扩展到实验报告的9个量子点（9-VSQDs）的垂直堆栈，已显示出显着的潜力，实现各向同性偏振特性。我们分析了在大的，实验测量，在平面偏振各向异性的形状不对称的贡献。我们的分析表明，基本伸长的方向控制的DOP的符号，然而，基本伸长的幅度只有一个非常小的影响DOP的幅度。我们进一步预测，椭圆形的9-VSQDs只能调整DOP或DOP的各向同性响应。我们的模型结果与TEM结果一致，表明实验生长的9-VSQDs具有圆形或略微细长的基底。总体而言，详细调查的DOP作为QD形状不对称性的函数提供了一个理论指导，为持续的实验努力，以实现定制的偏振性能从QD纳米结构的光学器件的设计。
The demonstration of isotropic polarization response from semiconductor quantum dots (QDs) is a crucial step towards the design of several optoelectronic technologies. Among many parameters that impact the degree of polarization (DOP) of a QD system, the shape asymmetry is a critical factor. We perform multi-million-atom simulations to study the impact of the elliptical shapes on the electronic and polarization properties of single and vertically stacked InAs QDs. The comparison between a low aspect ratio (AR) and a high AR QD reveals that the electronic and the polarization properties strongly depend on the AR of the QD; the elongation of a tall QD allows tuning of the DOPover a much wider range. We then extend our analysis to an experimentally reported vertical stack of nine QDs (9-VSQDs) that has shown significant potential to achieve isotropic polarization properties. We analyze the contribution from the shape asymmetry in the large, experimentally measured, in-plane polarization anisotropy. Our analysis shows that the orientation of the base elongation controls the sign of the DOP; however, the magnitude of the base elongation has only a very little impact on the magnitude of the DOP. We further predict that the elliptical shape of the 9-VSQDs can only tune either DOPor DOPfor the isotropic response. Our model results, in agreement with the TEM findings, suggest that the experimentally grown 9-VSQDs has either a circular or a slightly [10] elongated base. Overall, the detailed investigation of DOPas a function of the QD shape asymmetry provides a theoretical guidance for the continuing experimental efforts to achieve tailored polarization properties from QD nanostructures for the design of optical devices.