Oxygen Driven Defect Engineering of Monolayer MoS<sub>2</sub> for Tunable Electronic, Optoelectronic, and Electrochemical Devices
Irfan Haider Abidi, Sindhu Priya Giridhar, Jonathan O. Tollerud, Jake Limb, Moaz Waqar, Aishani Mazumder, Edwin L. H. Mayes, Billy J. Murdoch, Chenglong Xu, Ankit Bhoriya, Abhishek Ranjan, Taimur Ahmed, Yongxiang Li, Jeffrey A. Davis, Cameron L. Bentley, Salvy P. Russo, Enrico Della Gaspera, Sumeet Walia
Abstract
Abstract Molybdenum disulfide (MoS 2 ), a two‐dimensional (2D) semiconducting material harbors intrinsic defects that can be harnessed to achieve tuneable electronic, optoelectronic, and electrochemical devices. However, achieving precise control over defect formation within monolayer MoS 2 , remains a notable challenge. Here, an in‐situ defect engineering approach for monolayer MoS 2 using a pressure‐dependent chemical vapor deposition (CVD) process is presented. Monolayer MoS 2 grown in a low pressure CVD conditions (LP‐MoS 2 ) produces sulfur vacancy ( V s ) induced defect‐rich crystals primarily attributed to the oxygen‐deficient growth conditions. Conversely, atmospheric pressure CVD‐grown MoS 2 (AP‐MoS 2 ) passivates these defects with oxygen from ambient conditions. This disparity in defect profiles profoundly impacts crucial functional properties and device performance. AP‐MoS 2 shows a drastically enhanced photoluminescence, which is significantly quenched in LP‐MoS 2 attributed to in‐gap electron donor states induced by the V s defects. However, the n‐doping induced in LP‐MoS 2 generates enhanced photoresponsivity and detectivity in fabricated photodetectors compared to the AP‐MoS 2 ‐based devices. Defect‐rich LP‐MoS 2 outperforms AP‐MoS 2 as channel layers of field‐effect transistors (FETs), as well as electrocatalytic material for hydrogen evolution reaction (HER). This work presents a single‐step CVD approach for in situ defect engineering in monolayer MoS 2 and presents a pathway to control defects in other monolayer 2D materials.