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

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 46; pp. e2403225 - n/a
• Main Authors: Mallick, Sagar, Majumder, Sudipta, Maiti, Paramita, Kesavan, Kamali, Rahman, Atikur, Rath, Ashutosh
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-11-2024
• Subjects: 1T/2H‐MoS2; Carrier density; Carrier recombination; Chemical vapor deposition; FET; Field effect transistors; HRTEM; Molybdenum disulfide; Optoelectronics; Phase transitions; photodetector; Raman; Synthesis; Transition metal compounds
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202403225

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‐MoS2 and mixed‐phase 1T/2H‐MoS2 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‐MoS2 mixed‐phase show an on/off ratio of 107. Photo response devices fabricated with 1T/2H‐MoS2 mixed‐phase show ≈55 times enhancement in responsivity (from 0.32 to 17.4 A W−1) and 102 times increase in the detectivity (from 4.1 × 1010 to 2.48 × 1012 cm Hz W−1) compare to 2H‐MoS2. 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‐MoS2 mixed‐phase in comparison to 2H‐MoS2. This work provides insights into the self‐doping effects of 1T phase in 2H MoS2, enabling the tuning of 2D TMDs properties for optoelectronic applications.
Large‐area self‐doped, monolayer 2D MoS2 is successfully synthesized via the one‐step chemical vapor deposition method without the use of a catalyst. Notably, the self‐doped MoS2 (1T‐2H mixed‐phase) exhibits significantly enhanced photo responsivity (55 times higher), alongside improved detectivity, photo gain, and response time compared to the 2H phase.