High-responsivity PtSe₂ photodetector enhanced by photogating effect

Platinum diselenide (PtSe₂), a recently rediscovered two-dimensional transition metal dichalcogenide, has attracted immense attention in the optoelectronic field due to its tunable bandgap, ultrastability, and high electron mobility. However, the applications of PtSe₂ photodetectors are seriously restricted by their low responsivity. In this work, a high-responsivity (5 × 10⁴ A/W) PtSe₂ photodetector is obtained by exploiting a photogating effect; this is induced by the hole-trapping states, which are attributed to Se vacancies. Moreover, a gate-tunable transition between the positive and negative photoconductances is observed under light illumination. A theoretical calculation based on the Boltzmann transport theory is performed to explain the carrier transport of PtSe₂, considering the contributions of charged impurity, acoustic phonon, and polar optical phonon scattering.