Delocalization and bandgap engineering in defective MoS2 by metal ion doping for enhanced electrical performance and efficient near-infrared detection

Abstract

This study presents delocalization and bandgap engineering in defective MoS₂ by metal ion doping. Due to inevitable defects, MoS₂ field-effect transistors (FETs) exhibit unstable electrical characteristics. However, doping with indium, gallium, zinc, and oxygen ions using an IGZO layer enhances the stability and electrical performance of MoS₂ FETs and remarkably enables efficient detection of near-infrared light. Chemical and structural analyses reveal that metal ions diffuse into defective MoS₂, forming a few-nanometer-thick doped MoS₂ layer with a delocalized electronic structure and a reduced bandgap, and also a quasi-quantum well structure made of MoS₂, doped MoS₂, and IGZO. Current–voltage analyses and ab initio density functional theory calculations reveal that, due to the delocalized doped layer and the quasi-quantum-well structure, charge transport is confined to the layer, leading to remarkable near-infrared detection properties and band-like charge transport. We thus regard the doping-induced delocalization and bandgap engineering in defective MoS₂ as a promising strategy for next-generation optoelectronic applications.