Isotropic conduction and negative photoconduction in ultrathin PtSe₂ films

$PtSe2$ ultrathin films are used as the channel of back-gated field-effect transistors that are investigated at different temperatures and under super-continuous white laser irradiation. The temperature-dependent behavior confirms the semiconducting nature of multilayer $PtSe2$⁠, with p-type conduction, a hole field-effect mobility up to $40 cm2 V−1 s−1$⁠, and significant gate modulation. Electrical conduction measured along different directions shows isotropic transport. A reduction of $PtSe2$ channel conductance is observed under exposure to light. Such a negative photoconductivity is explained by a photogating effect caused by photo-charge accumulation in SiO₂ and at the $Si/SiO2$ interface.