Analysis of Carrier Transport in Quantum Dot/Metal-Oxide Phototransistors via Light-Mediated Interfacial Modeling

Abstract

Quantum dot (QD) hybrid phototransistors based on high-mobility channel semiconductors have attracted great interest due to their outstanding photonic characteristics with diverse and broadband optoelectronic functionalities. However, difficulties for precise control of electronic coupling between QD particles and lack of QD/semiconductor interface analysis have limited the use of these platforms into practical optoelectronic applications. Here, the authors report a new strategy to high-performance phototransistors based on CdSe QD/amorphous oxide semiconductor heterostructures using trap-reduced chelating chalcometallate surface ligands by optimizing the QD layer thickness and interface engineering to enhance photogenerated charge transfer properties. Furthermore, based on performance parameters extracted from experimental structure and electrical characteristics, Technology Computer-Aided Design (TCAD) modeling reveals carrier flow between the QDs in the semiconductor layer in agreement with various spectroscopic data. These modeling results indicate that interface engineering of QD with chalcometallate ligand results in very efficient photo-induced charge transfer characteristics. Thus, high-performance chalcometallate ligand QD-based phototransistors are successfully realized with enhanced responsivity (2.12 x 10(4) A W-1) and photodetectivity (2.74 x 10(16) Jones) compared with conventional monodentate ligand functionalized (SCN-) QD-based devices (8.79 x 10(3) A W-1 and 8.8 x 10(10) Jones, respectively). This is the demonstration of systematic analysis of QD-based hetero-structured phototransistors with light-mediated interfacial physical modeling and electrochemical measurement.