Understanding the Charge Transport Mechanism in MoS 2 Transistors with Graphene Electrodes
- PDF / 509,478 Bytes
- 4 Pages / 595.22 x 842 pts (A4) Page_size
- 45 Downloads / 179 Views
Understanding the Charge Transport Mechanism in MoS2 Transistors with Graphene Electrodes Jisu Jang and Do Kyung Hwang
∗
Center of Opto-Electronic Materials and Devices, Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea and Division of Nano & Information Technology, KIST School, University of Science and Technology (UST), Seoul 02792, Korea (Received 6 August 2020; revised 8 September 2020; accepted 9 September 2020) Two-dimensional transition-metal dichalcogenides (TMDs) have emerged as promising candidates for next-generation electronics owing to their excellent semiconducting properties. However, metalTMDs junctions are of particular interest as they have become a major limiting factors to further improvements in TMD-based device performance. Here, we investigate the charge transport of MoS2 transistors contacted with Ti/Au and graphene electrodes. Compared to a conventional Ti/Au contact, the MoS2 devices with graphene electrodes exhibit improved electrical properties (field-effect mobility, subthreshold swing, and low off-state current). Such a device improvement could be attributed to efficient electron injection arising from the tunable graphene Fermi level as well as the high hole barrier height, which significantly reduces the off-state current caused by hole transport. Furthermore, a simple Schottky barrier model has been employed to explain the observed transfer characteristic of MoS2 transistors with two different contacts. Our finding provides significant insights into the understanding of charge transport in TMD-based transistors for future 2D electronics. Keywords: Molybdenum disulfide, Graphene, Schottky barrier height, Field-effect transistors DOI: 10.3938/jkps.77.1008
I. INTRODUCTION Two-dimensional transition-metal dichalcogenides (TMDs) have received significant attention due to their unique electronic and optoelectronic properties [1, 2]. Among the various TMDs, molybdenum disulfide (MoS2 ) has been the most extensively explored for semiconductor applications because of its advantages, such as a high mobility (700 cm2 V−1 s−1 from mechanical exfoliated MoS2 transistors) [3], a sizable band gap (1.2–1.8 eV), and a high on/off ratio (up to 108 ) [4]. Although MoS2 is a promising material for electronics, its transistor characteristics are largely determined by its contact properties [5]. Thus, controlling the Schottky barrier height (SBH) at source/drain contacts, which is very related to the contact properties, is a mandatory requirement, but remains a significant challenge. Various approaches, including contact work function engineering [3], molecular/chemical doping [6, 7], and van der Waals contacts via mechanical transfer of metal electrodes, have been made to control the Schottky barrier at contacts [5]. Recently, graphene has been proposed as an electrode ∗ E-mail:
[email protected]
pISSN:0374-4884/eISSN:1976-8524
material for achieving an ohmic contact to TMDs [8, 9]. In such devices, the SBH at the graphene-TMD junction can be effectively modu
Data Loading...
