Development of Self‐Doped Monolayered 2D MoS2 for Enhanced Photoresponsivity

Abstract Transition metal dichalcogenides (TMDs) exist in two distinct phases: the thermodynamically stable trigonal prismatic (2H) and the metastable octahedral (1T) phase. Phase engineering has emerged as a potent technique for enhancing the performance of TMDs in optoelectronics applications. Nevertheless, understanding the mechanism of phase transition in TMDs and achieving large‐area synthesis of phase‐controlled TMDs continue to pose significant challenges. This study presents the synthesis of large‐area monolayered 2H‐MoS 2 and mixed‐phase 1T/2H‐MoS 2 by controlling the growth temperature in the chemical vapor deposition (CVD) method without use of a catalyst. The field‐effect transistors (FETs) devices fabricated with 1T/2H‐MoS 2 mixed‐phase show an on/off ratio of 10 7 . Photo response devices fabricated with 1T/2H‐MoS 2 mixed‐phase show ≈55 times enhancement in responsivity (from 0.32 to 17.4 A W −1 ) and 10 2 times increase in the detectivity (from 4.1 × 10 10 to 2.48 × 10 12 cm Hz W −1 ) compare to 2H‐MoS 2 . Introducing the metallic 1T phase within the 2H phase contributes additional carriers to the material, which prevents the electron‐hole recombination and thereby increases the carrier density in the 1T/2H‐MoS 2 mixed‐phase in comparison to 2H‐MoS 2. This work provides insights into the self‐doping effects of 1T phase in 2H MoS 2 , enabling the tuning of 2D TMDs properties for optoelectronic applications.