Single-layer MoS2 transistors

Abstract

Two-dimensional materials are attractive for use in next-generation nanoelectronic devices because, compared to one-dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two-dimensional material is graphene1,2, both because of its rich physics3,4,5 and its high mobility6. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors7. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films8,9,10,11,12,13 or requires high voltages14,15. Although single layers of MoS2 have a large intrinsic bandgap of 1.8 eV (ref. 16), previously reported mobilities in the 0.5–3 cm2 V−1 s−1 range17 are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room-temperature single-layer MoS2 mobility of at least 200 cm2 V−1 s−1, similar to that of graphene nanoribbons, and demonstrate transistors with room-temperature current on/off ratios of 1 × 108 and ultralow standby power dissipation. Because monolayer MoS2 has a direct bandgap16,18, it can be used to construct interband tunnel FETs19, which offer lower power consumption than classical transistors. Monolayer MoS2 could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting. The large bandgap of a single layer of molybdenum disulphide can be exploited to construct transistors with high on/off ratios and high mobilities.