Kim Minkyong, Han Chang-Yeol, Yang Heesun, Park Byoungnam
Department of Materials Science and Engineering, Hongik University 72-1, Sangsu-dong, Mapo-gu, Seoul 04066, Korea.
Materials (Basel). 2019 Jul 17;12(14):2289. doi: 10.3390/ma12142289.
We provide a comprehensive understanding of interfacial charge transfer at the lead selenide (PbSe) quantum dot (QD)/zinc oxide (ZnO) interface, proposing band to band tunneling process as a charge transfer mechanism in which initial hopping of carriers from ZnO to PbSe QDs is independent of temperature. Using the transmission line method (TLM) in a ZnO/PbSe/ZnO geometry device, we measured the ZnO/PbSe electrical contact resistance, a measure of charge transfer efficiency. Fabrication of a highly conductive ZnO film through Al doping allows for the formation of ZnO source and drain electrodes, replacing conventional metal electrodes. We found that band to band tunneling at the PbSe QD/ZnO interface governs charge transfer based on temperature-independent PbSe QD/ZnO contact resistance. In contrast, the PbSe QD channel sheet resistance decreased as the temperature increased, indicating thermally activated transport process in the PbSe QD film. These results demonstrate that, at the ZnO/PbSe QD interface, temperature-independent tunneling process initiates carrier injection followed by thermally activated carrier hopping, determining the electrical contact resistance.
我们全面了解了硒化铅（PbSe）量子点（QD）/氧化锌（ZnO）界面处的界面电荷转移，提出带间隧穿过程作为一种电荷转移机制，其中载流子从ZnO到PbSe量子点的初始跳跃与温度无关。在ZnO/PbSe/ZnO几何结构的器件中使用传输线方法（TLM），我们测量了ZnO/PbSe的电接触电阻，这是电荷转移效率的一种度量。通过铝掺杂制备高导电的ZnO薄膜，使得能够形成ZnO源极和漏极，取代传统的金属电极。我们发现，基于与温度无关的PbSe量子点/ZnO接触电阻，PbSe量子点/ZnO界面处的带间隧穿控制着电荷转移。相比之下，PbSe量子点沟道的薄层电阻随着温度升高而降低，表明PbSe量子点薄膜中存在热激活输运过程。这些结果表明，在ZnO/PbSe量子点界面处，与温度无关的隧穿过程引发载流子注入，随后是热激活的载流子跳跃，这决定了电接触电阻。
