Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors.

Lien, Der-Hsien; Uddin, Shiekh Zia; Yeh, Matthew; Amani, Matin; Kim, Hyungjin; Ager, Joel W; Yablonovitch, Eli; Javey, Ali · Science · 2019

basic_science · Level V

Where this comes from

Abstract

Defects in conventional semiconductors substantially lower the photoluminescence (PL) quantum yield (QY), a key metric of optoelectronic performance that directly dictates the maximum device efficiency. Two-dimensional transition-metal dichalcogenides (TMDCs), such as monolayer MoS<sub>2</sub>, often exhibit low PL QY for as-processed samples, which has typically been attributed to a large native defect density. We show that the PL QY of as-processed MoS<sub>2</sub> and WS<sub>2</sub> monolayers reaches near-unity when they are made intrinsic through electrostatic doping, without any chemical passivation. Surprisingly, neutral exciton recombination is entirely radiative even in the presence of a high native defect density. This finding enables TMDC monolayers for optoelectronic device applications as the stringent requirement of low defect density is eased.