Electronic Modulation of Semimetallic Electrode for 2D van der Waals Devices

• Published in: Small structures 2023-05, Vol.4 (5), p.n/a
• Main Authors: Kim, Taehun, Lim, Jungmoon, Byeon, Junsung, Cho, Yuljae, Kim, Woojong, Hong, Jinpyo, Jin Heo, Su, Eun Jang, Jae, Kim, Byung-Sung, Hong, John, Pak, Sangyeon, Cha, SeungNam
• Format: Article
• Language: English
• Subjects: Configurations; contact engineering; Copper sulfides; CuS electrodes; electrode dopants; Electrodes; Energy bands; Field effect transistors; Iodine; Material properties; Modulation; Molybdenum disulfide; MoS2 monolayers; ohmic contacts; Phototransistors; Semiconductor devices; semimetallic electrodes; Strain
• ISSN: 2688-4062; 2688-4062
• DOI: 10.1002/sstr.202200274

The 2D semimetallic electrodes have been employed to show outstanding contact properties with 2D semiconducting transition‐metal dichalcogenides (TMDCs) channel, leading to large enhancement of 2D transistor and phototransistor performance. Herein, an innovative concept is established for a unique 2D semimetallic electrode‐2D TMDC channel (2D–2D) device configuration where the electronic structures of 2D semimetallic electrodes are systematically modulated to improve the contact properties with 2D monolayer molybdenum disulfide (MoS2) channel. The 2D semimetallic copper sulfide (CuS) electrodes are doped with iodine atoms by a direct exposure of iodine gas. The contact properties and charge‐transport behavior in the 2D–2D field‐effect transistors (FETs) are highly improved, which is attributed to the favorable energy band alignment and associated material properties between the iodine‐doped CuS (CuS–I) electrodes and 2D channel. The 2D–2D FETs show a high on current, high on/off ratio, and twofold improvement in mobility. Furthermore, 2D–2D phototransistors and flexible/transparent photodetectors are fabricated using the CuS–I/MoS2, which also performed outstanding photoresponsivity characteristics and mechanical durability under external bending strain conditions. These findings demonstrate a promising pathway that under the 2D–2D configuration, the electronic modulation by the iodine atoms may enable the development of future 2D electronic applications. A simple yet innovative approach to form low‐resistance contacts with 2D semiconductor. Practical and viable solution for the enhanced electrode properties of ultrathin semimetallic CuS is provided. Iodine‐doped CuS electrode and 2D MoS2 channel show high on current, high on/off ratio, and twofold improvement in mobility.