电场驱动HgCdTe/CdTe量子阱拓扑相变引起的光吸收增强研究

HgTe/CdTe量子阱是研究拓扑绝缘体新奇物性的一个很好载体。采用Kane八带k·p模型,对电场驱动Hg1-xCdxTe/CdTe量子阱拓扑相变及其相变前后的光吸收性质进行了研究,并使用BHZ模型对吸收系数进行了解析计算和分析。结果表明:在电场能够驱动Hg1-xCdxTe/CdTe量子阱拓扑相变后继续增大电场,其能带可变为墨西哥帽形状,联合态密度将会增强,导致光吸收相比于无电场时显著增强,与解析计算结果相吻合。对于平行界面偏振光(TE)吸收曲线在带边还形成了双峰结构。文章结果可用于新型红外光电探测器、激光器以及频率选择器等量子阱器件的研究和设计。

The Enhancement of Optical Absorption in HgCdTe/CdTe Quantum Well Induced by Electric Field Driven Topological Phase Transition

HgTe/CdTe quantum well is a good platform for the research the unique properties of topological insulator. The electric field driven Hg1-xCdxTe/CdTe quantum well topological phase transition and the corresponding optical absorption were investigated by Kane eight band k·p model. Moreover, the optical absorption was analytically calculated through Bernevig Hughes Zhang (BHZ) model. The results show that the electric field can drive the topological phase transition. Further increasing the electric field will distort the lowest conduction band and the highest valence band into a mexican hat shape. The special energy band shape will lead to a significant enhancement of the joint density of states as well as the optical absorption, which are consistent with the analytical results. Meanwhile, the absorption curve will form two humped structure for the transverse electric mode (TE). Our results can provide new design guidance for infrared photodetectors, lasers and frequency selectors.