Ultrafast response of monolayer molybdenum disulfide photodetectors

The strong light emission and absorption exhibited by single atomic layer transitional metal dichalcogenides in the visible to near-infrared wavelength range make them attractive for optoelectronic applications. In this work, using two-pulse photovoltage correlation technique, we show that monolayer molybdenum disulfide photodetector can have intrinsic response times as short as 3 ps implying photodetection bandwidths as wide as 300 GHz. The fast photodetector response is a result of the short electron–hole and exciton lifetimes in this material. Recombination of photoexcited carriers in most two-dimensional metal dichalcogenides is dominated by nonradiative processes, most notable among which is Auger scattering. The fast response time, and the ease of fabrication of these devices, make them interesting for low-cost ultrafast optical communication links. Two-dimensional transition-metal dichalcogenides are useful for optoelectronic applications, but the ultimate limit on the speed of photodetector operation is unknown. Here, the authors show that the optical response time of monolayer molybdenum disulfide can be as short as three picoseconds.