纤锌矿晶体结构
声子
量子点
激光线宽
激子
凝聚态物理
材料科学
各向异性
光致发光
合金
格子(音乐)
光电子学
分子物理学
化学
激光器
光学
物理
锌
冶金
复合材料
声学
作者
Linfeng Wang,Jinke Bai,Tingting Zhang,Xinghua Huang,Tianyi Hou,Bing Xu,Dongyu Li,Qinghua Li,Xiao Jin,Yuxiao Wang,Xueru Zhang,Song Ye
标识
DOI:10.1016/j.jcis.2022.05.140
摘要
The emission linewidth of quantum dots (QDs) is one of the important optical properties, which is essential for the applications of QD lasers, high-quality displays, and biological imaging. However, we know less about controlling emission linewidth and its underlying mechanisms. Here we introduce a wurtzite ZnSe shell onto a wurtzite CdSe core to produce asymmetric strain due to their large, anisotropic lattice mismatch. Such asymmetric pressure induces significant splitting (ΔAB) between heavy-hole (hh) and light-hole (lh) in valence band (VB). We show that the emission intensity from the lh state (Elh) is significantly suppressed with the increasing ΔAB caused by the strong asymmetric strain. We demonstrate that the exciton-phonon coupling (EPC) is greatly inhibited under the anisotropic lattice strain. The alloying process between the core and shell occurs under the strong lattice strain and raises the longitudinal-optical (LO) phonon energy (ELO). Higher LO phonon energy declines LO phonon occupation numbers (NLO) and synergistically reduces the EPC. The asymmetrically strained alloy QDs ensemble exhibits highly bright emission with ultra-narrow linewidths of 13.8 nm (∼520 nm) and 15.8 nm (∼620 nm). This concept of band structure regulation via asymmetric strain can provide a new platform for high-quality QDs beyond the currently achieved.
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