Composition‐Triggered Growth of Monolayer MoTe2(1−x)S2x Alloys with Coherent Phase Interfaces for High‐Performance Broadband Photodetection

Abstract 2D transitional metal dichalcogenides (TMDs) have attracted great interest for their advantageous application in room‐temperature broadband photodetectors. Developing effective strategies to optimize the photo‐carrier dynamical process of monolayer TMDs is still urgently necessary to extend wavelength range and reduce dark current due to the theoretical limitation of their intrinsic band structure. Herein, an interesting approach is reported to realize broadband photodetection from 532 to 1550 nm with low dark current for the first time by using composition‐triggered growth of coherent atomic structures of enriched nanoscale mix‐phase (2H/1T') monolayer MoTe 2(1− x ) S 2 x alloys. The morphology and phase evolution at the nanoscale of monolayer MoTe 2(1− x ) S 2 x alloys are elucidated as affected by tiny formation energy (Δ E ) by the chemical composition of S/Te atoms triggered. As‐grown enriched nanoscale mix‐phase (2H/1T') of monolayer MoTe 2(1− x ) S 2 x alloys devices exhibit typical n‐type conductivity properties. More interestingly, the devices show an extended photo‐response range from 532 to 1550 nm with reduced dark current to 10 −10 A at 100 mV bias voltage. This work demonstrates that coherent atomic structure of enriched nanoscale mix‐phase (2H/1T′) monolayer TMDs alloys can be an alternative approach to obviously extend photo‐response wavelength range without increasing dark current for room temperature broadband photodetection.