Hudson Margaret H, Chen Menglu, Kamysbayev Vladislav, Janke Eric M, Lan Xinzheng, Allan Guy, Delerue Christophe, Lee Byeongdu, Guyot-Sionnest Philippe, Talapin Dmitri V
University of Lille, CNRS, Centrale Lille, ISEN, University of Valenciennes , UMR 8520 - IEMN, F-59000 Lille , France.
ACS Nano. 2018 Sep 25;12(9):9397-9404. doi: 10.1021/acsnano.8b04539. Epub 2018 Aug 24.
HgTe colloidal quantum dots (QDs) are of interest because quantum confinement of semimetallic bulk HgTe allows one to synthetically control the bandgap throughout the infrared. Here, we synthesize highly monodisperse HgTe QDs and tune their doping both chemically and electrochemically. The monodispersity of the QDs was evaluated using small-angle X-ray scattering (SAXS) and suggests a diameter distribution of ∼10% across multiple batches of different sizes. Electron-doped HgTe QDs display an intraband absorbance and bleaching of the first two excitonic features. We see splitting of the intraband peaks corresponding to electronic transitions from the occupied 1S state to a series of nondegenerate 1P states. Spectroelectrochemical studies reveal that the degree of splitting and relative intensity of the intraband features remain constant across doping levels up to two electrons per QD. Theoretical modeling suggests that the splitting of the 1P level arises from spin-orbit coupling and reduced QD symmetry. The fine structure of the intraband transitions is observed in the ensemble studies due to the size uniformity of the as-synthesized QDs and strong spin-orbit coupling inherent to HgTe.
碲化汞胶体量子点（QDs）备受关注，因为半金属块状碲化汞的量子限制效应使人们能够在整个红外波段合成控制带隙。在此，我们合成了高度单分散的碲化汞量子点，并通过化学和电化学方法调节其掺杂。利用小角X射线散射（SAXS）评估了量子点的单分散性，结果表明在多批不同尺寸的量子点中，直径分布约为10%。电子掺杂的碲化汞量子点表现出带内吸收以及前两个激子特征的漂白现象。我们观察到带内峰的分裂，这对应于从占据的1S态到一系列非简并1P态的电子跃迁。光谱电化学研究表明，在每个量子点掺杂多达两个电子的情况下，带内特征的分裂程度和相对强度在不同掺杂水平下保持恒定。理论模型表明，1P能级的分裂源于自旋 - 轨道耦合和量子点对称性的降低。由于合成的量子点尺寸均匀以及碲化汞固有的强自旋 - 轨道耦合，在整体研究中观察到了带内跃迁的精细结构。
