P-type Ohmic contact to monolayer WSe<sub>2</sub> field-effect transistors using high electron affinity amorphous MoO<sub>3</sub>
ORAL
Abstract
Monolayer tungsten diselenide (1L-WSe2) has recently received attention because of its favorable band structure for probing novel correlated phenomena of p-type carriers, such as interaction-driven and topological insulating phases and superconductivity in twisted bilayers, and Bose-Einstein condensation of excitons in double-layer heterostructures. However, electrical transport studies have been impeded by the lack of a reliable method to realize Ohmic hole-conducting contacts to 1L-WSe2 especially at low carrier densities and low temperatures. Here, we present low-temperature p-type Ohmic contact to 1L-WSe2 field-effect transistors at carrier densities (n) below n = 1 × 1012 cm−2. Monolayer WSe2 was sandwiched by hexagonal boron nitride flakes by a dry transfer technique and electrically contacted with 20 nm thick amorphous MoO3 followed by Pd metal. The finding of p-type Ohmic contact is supported by linear current-voltage characteristics down to a temperature of 10 K and carrier densities from n = 7.7 × 1011 cm−2 to below the threshold, temperature-independent output curves up to room temperature, and negligible contact barrier down to subthreshold regime. Furthermore, the contact resistivity of MoO3-contacted 1L-WSe2 FET is 30.2–64.8 kΩ·μm at n = 1.5 × 1012 cm−2, which is the lowest reported for 1L-WSe2 FETs at such low carrier density. Achieving p-type Ohmic contact in 1L-WSe2 FETs will enable direct electronic measurements of quantum transport in correlated phases in the valence bands of monolayer semiconductors.
*ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET; CE170100039); JSPS KAKENHI (Grant Numbers 19H05790, 20H00354 and 21H05233); Center of Atomic Initiative for New Materials, National Taiwan University (grant nos. 110 L9008 and 111 L9008), from the Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education of Taiwan; ARC grant DP200101345;
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Publication: https://arxiv.org/abs/2206.11096
Presenters
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Yi-Hsun Chen
- Monash University