Band to Band Tunneling at the Zinc Oxide (ZnO) and Lead Selenide (PbSe) Quantum Dot Contact; Interfacial Charge Transfer at a ZnO/PbSe/ZnO Probe Device

• Published in: Materials Vol. 12; no. 14; p. 2289
• Main Authors: Kim, Minkyong, Han, Chang-Yeol, Yang, Heesun, Park, Byoungnam
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 17.07.2019; MDPI
• Subjects: Acids; Carrier injection; Charge efficiency; Charge transfer; Contact resistance; Efficiency; Electric contacts; Electrical resistance; Electrodes; Energy; Engineering; field effect transistor; Geometry; Lead selenides; Ligands; Light emitting diodes; localized states; Optimization; PbSe; quantum dot; Quantum dots; Transmission lines; Zinc oxide; Zinc oxides; ZnO; quantum dot; PbSe; ZnO; field effect transistor; charge transfer; localized states
• ISSN: 1996-1944; 1996-1944
• 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.