Depleted Nanocrystal-Oxide Heterojunctions for High-Sensitivity Infrared Detection
Technical Report,01 Sep 2014,31 May 2015
West Virginia University Morgantown United States
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The goal of this project is to explore a new IR photodetector architecture based on a depleted ZnOPbS QD heterojunction. Colloidal PbSQDs with the first excitonic absorption peak from 850-1050 nm were synthesized, and ZnO thin films were prepared by two different methods thermal evaporation and solution processing. Devices with an optimized ZnOPhS QD structure showed ultralow dark current, fast response, and a photocurrent onoff ratio greater than 10000. A comparative study of ZnO or PhS QD single-layer structures proved that the optical response arises from charge separation at a depleted junction forming between ZnO and PbS QDs. However, poor charge transport through the solution-processed ZnO and QD layers limits the photoconductive gain and quantum efficiency of devices.