Theoretical Study Of The Photocurrent In Transition-Metal Dichalcogenide Materials

Motivated by photocurrent spectroscopy experiments with MoS2, the direct band-to-band transition contribution to the photocurrent of transition-metal dichalcogenides is computed starting from the microscopic Hamiltonian in the Keldysh-Schwinger formalism. It turns out that the band tilting induced by source to drain voltage is necessary for a nonvanishing photocurrent. The photon energy dependence of the normalized photocurrent is found to be consistent with experimental data. For circular polarization the helicity-dependent component of the photocurrent perpendicular to the band-tilting direction is predicted, which essentially originates from the valley Hall effect.