Semimetal-Monolayer Transition Metal Dichalcogenides Photodetectors for Wafer-Scale Broadband Photonics

Atomically thin 2D transition metal dichalcogenides (TMDs), such as MoS2, are promising candidates for nanoscale photonics because of strong light-matter interactions. However, Fermi-level pinning due to metal-induced gap states (MIGS) at the metal-monolayer (1L)-MoS2 interface limits the application of optoelectronic devices based on conventional metals due to high contact resistance. On the other hand, a semimetal-TMD-semimetal device can overcome this limitation, where the MIGS are sufficiently suppressed allowing ohmic contacts. Herein, the optoelectronic performance of a bismuth-1L-MoS2-bismuth device with ohmic electrical contacts and extraordinary optoelectronic properties is demonstrated. To address the wafer-scale production, full coverage 1L-MoS2 grown by chemical vapor deposition. High photoresponsivity of 300 A W-1 at wavelength 400 nm measured at 77 K, which translates into an external quantum efficiency (EQE) approximate to 1000 or 10(5)%, is measured. The 90% rise time of the devices at 77 K is 0.1 ms, suggesting they can operate at the speed of approximate to 10 kHz. High-performance broadband photodetector with spectral coverage ranging from 380 to 1000 nm is demonstrated. The combination of large-array device fabrication, high sensitivity, and high-speed response offers great potential for applications in photonics, including integrated optoelectronic circuits.

Automated summary

Researchers demonstrated a bismuth-1L-MoS2-bismuth device with ohmic electrical contacts and extraordinary optoelectronic properties by suppressing metal-induced gap states (MIGS) at the metal-monolayer MoS2 interface. This overcomes Fermi-level pinning and expands the application range of optoelectronic devices based on 2D transition metal dichalcogenides.