Ultrafast Charge Carrier Dynamics and Transport Characteristics in HgTe Quantum Dots

作者：Kseniia A. Sergeeva, Kezhou Fan, Aleksandr A. Sergeev, Sile Hu, Haochen Liu, Christopher C. S. Chan, Stephen V. Kershaw, Kam Sing Wong, Andrey L. Rogach · 发表于：The Journal of Physical Chemistry C · 年份：2022 · DOI：10.1021/acs.jpcc.2c05348 · 被引用次数：20 · 研究领域：Quantum Dots Synthesis And Properties、Chalcogenide Semiconductor Thin Films、Advanced Semiconductor Detectors and Materials

We investigate the charge carrier dynamics in HgTe quantum dots emitting in the second near-infrared window (1000–2500 nm). To provide a link between fundamental physics and practical application, we made consistent studies of the charge carrier dynamics evolution for quantum dots in different states: colloidal solutions of quantum dots capped with a long-chain ligand; thin films made from them; and finally, exchanged to short-chain ligand films suitable for field effect transistor based devices. Ultrafast transient absorption spectroscopy reveals an ultralow Auger-related nonradiative relaxation threshold at 0.1 exciton per quantum dot, both in colloidal solutions and solid films, with a rate of 30 ns –1 . The exchange from long- to short-chain ligands causing closer packing of the HgTe quantum dots leads to a strong increase of the Auger recombination rate of up to 100 ns –1 . The competition between the Auger process and excitonic recombination significantly affects the performance of HgTe-based thin film photodetectors operating at room temperature, resulting in a 2 orders of magnitude drop in responsivity when the excitation flux was increased from 0.01 to 5 W·cm –2 .