Maier Andre, Strauß Fabian, Kohlschreiber Pia, Schedel Christine, Braun Kai, Scheele Marcus
Institute of Physical and Theoretical Chemistry, Universität Tübingen, Auf der Morgenstelle 18, D-72076Tübingen, Germany.
Center for Light-Matter Interaction, Sensors and Analytics LISA+, Universität Tübingen, Auf der Morgenstelle 15, D-72076 Tübingen, Germany.
Nano Lett. 2022 Apr 13;22(7):2809-2816. doi: 10.1021/acs.nanolett.1c04938. Epub 2022 Mar 21.
Colloidal nanocrystals (NCs), especially lead sulfide NCs, are promising candidates for solution-processed next-generation photodetectors with high-speed operation frequencies. However, the intrinsic response time of PbS-NC photodetectors, which is the material-specific physical limit, is still elusive, as the reported response times are typically limited by the device geometry. Here, we use the two-pulse coincidence photoresponse technique to identify the intrinsic response time of 1,2-ethanedithiol-functionalized PbS-NC photodetectors after femtosecond-pulsed 1560 nm excitation. We obtain an intrinsic response time of ∼1 ns, indicating an intrinsic bandwidth of ∼0.55 GHz as the material-specific limit. Examination of the dependence on laser power, gating, bias, temperature, channel length, and environmental conditions suggest that Auger recombination, assisted by NC-surface defects, is the dominant mechanism. Accordingly, the intrinsic response time might further be tuned by specifically controlling the ligand coverage and trap states. Thus, PbS-NC photodetectors are feasible for gigahertz optical communication in the third telecommunication window.
胶体纳米晶体（NCs），尤其是硫化铅NCs，是具有高速工作频率的溶液处理下一代光电探测器的有前途的候选材料。然而，硫化铅-NC光电探测器的本征响应时间，即材料特定的物理极限，仍然难以捉摸，因为报道的响应时间通常受器件几何结构的限制。在这里，我们使用双脉冲符合光响应技术来确定在飞秒脉冲1560 nm激发后1,2-乙二硫醇功能化的硫化铅-NC光电探测器的本征响应时间。我们获得了约1 ns的本征响应时间，表明作为材料特定极限的本征带宽约为0.55 GHz。对激光功率、门控、偏置、温度、沟道长度和环境条件的依赖性研究表明，由NC表面缺陷辅助的俄歇复合是主导机制。因此，本征响应时间可能通过具体控制配体覆盖率和陷阱态进一步调整。因此，硫化铅-NC光电探测器对于第三电信窗口中的千兆赫光通信是可行的。
