Ultra-high Photoresponsivity in Suspended Metal-SemiconductorMetal Mesoscopic Multilayer MoS2 Broadband Detector from UV-to-IR with Low Schottky Barrier Contacts

The design, fabrication, and characterization of ultra-high responsivity photodetectors based on mesoscopic multilayer MoS2 is presented, which is a less explored system compared to direct band gap monolayer MoS2 that has received increasing attention in recent years. The device architecture is comprised of a metal-semiconductor-metal (MSM) photodetector, where Mo was used as the contact metal to suspended MoS2 membranes. The photoresponsivity R was measured to be similar to 1.4 x 10(4) A/W, which is > 10(4) times higher compared to prior reports, while the detectivity D* was computed to be similar to 2.3 x 10(11) Jones at 300 K at an optical power P of similar to 14.5 pW and wavelength lambda of similar to 700 nm. In addition, the dominant photocurrent mechanism was determined to be the photoconductive effect (PCE), while a contribution from the photogating effect was also noted from trap-states that yielded a wide spectral photoresponse from UV-to-IR (400 nm to 1100 nm) with an external quantum efficiency (EQE) similar to 10(4). From time-resolved photocurrent measurements, a decay time tau(d) similar to 2.5 ms at 300 K was measured from the falling edge of the photogenerated waveform after irradiating the device with a stream of incoming ON/OFF white light pulses.