Trilayered MoS$_{\bf 2}$ Metal –Semiconductor–Metal Photodetectors: Photogain and Radiation Resistance

Trilayered MoS
₂
metal-semiconductor-metal (MSM) photodetectors (PDs) exhibit the photogain is up to 24 with high responsivity (~1.04 A/W). This is because photocarriers generated at the MoS2 between two Au electrodes drift toward the metal-semiconductor interfaces due to band bending under applied bias and are then trapped at the surface state sites at the Au/MoS
₂
interfaces, giving rise to the decrease in Schottky barrier height. Moreover, MoS
₂
MSM PDs show fast operation speed; as the contact spacing reduces from 8 to 4 μm, the rise time and fall time of PDs reduce from 70 to 40 μs and from 110 to 50 μs, respectively. Trilayered MoS
₂
MSM PDs can operate even after 2-MeV proton illumination with ~10
¹¹
cm
^-2
fluences, indicating the high radiation tolerance. This work demonstrates that trilayer MoS
₂
opens up a new dimension for 2-D nanomaterial applications in harsh electronics.