Monolayer MoSe<inf>2</inf> grown by chemical vapor deposition for fast photodetection

Abstract

Monolayer molybdenum disulfide (MoS ) has become a promising building block in optoelectronics for its high photosensitivity. However, sulfur vacancies and other defects significantly affect the electrical and optoelectronic properties of monolayer MoS devices. Here, highly crystalline molybdenum diselenide (MoSe ) monolayers have been successfully synthesized by the chemical vapor deposition (CVD) method. Low-temperature photoluminescence comparison for MoS and MoSe monolayers reveals that the MoSe monolayer shows a much weaker bound exciton peak; hence, the phototransistor based on MoSe presents a much faster response time (<25 ms) than the corresponding 30 s for the CVD MoS monolayer at room temperature in ambient conditions. The images obtained from transmission electron microscopy indicate that the MoSe exhibits fewer defects than MoS . This work provides the fundamental understanding for the differences in optoelectronic behaviors between MoSe and MoS and is useful for guiding future designs in 2D material-based optoelectronic devices. © 2014 American Chemical Society. 2 2 2 2 2 2 2 2 2 2 2