Photocurrent Measurement of Monolayer Transition Metal Dichalcogenides*

Monolayer transition metal dichalcogenides (TMDs) exhibit unique excitonic physics due to the reduced screening and enhanced Coulomb interactions. The strong light matter interaction in monolayer TMDCs gives rise to large response of photocurrent which involves carrier extraction after the excitation of the exciton. Photocurrent measurement thus provides a unique tool to investigate the combined effects of optical absorption and gain mechanism, revealing the spatial electric field distribution and photocurrent generation mechanism. The monolayer TMDs based photodetector exhibits large signal to noise ratio and can be exploited for sensitive photon sensor. The photocurrent measurement can also read out the valley degree of freedom of monolayer TMDs, excited by light of certain helicity.