Abstract
Source/Drain extension doping is crucial for minimizing the series resistance of the ungated channel and reducing the contact resistance of field-effect transistors (FETs) in complementary metal–oxide–semiconductor (CMOS) technology. 2D semiconductors, such as MoS2 and WSe2, are promising channel materials for beyond-silicon CMOS. A key challenge is to achieve extension doping for 2D monolayer FETs without damaging the atomically thin material. This work demonstrates extension doping with low-resistance contacts for monolayer WSe2 p-FETs. Self-limiting oxidation transforms a bilayer WSe2 into a hetero-bilayer of a high-work-function WOxSey on a monolayer WSe2. Then, damage-free nanolithography defines an undoped nano-channel, preserving the high on-current of WOxSey-doped FETs while significantly improving their on/off ratio. The insertion of an amorphous WOxSey interlayer under the contacts achieves record-low contact resistances for monolayer WSe2 over a hole density range of 1012 to 1013 cm−2 (1.2 ± 0.3 kΩ µm at 1013 cm−2). The WOxSey-doped extension exhibits a sheet resistance as low as 10 ± 1 kΩ □−1. Monolayer WSe2 p-FETs with sub-50 nm channel lengths reach a maximum drain current of 154 µA µm−1 with an on/off ratio of 107–108. These results define strategies for nanometer-scale selective-area doping in 2D FETs and other 2D architectures.
Original language | English (US) |
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Journal | Advanced Electronic Materials |
DOIs | |
State | Accepted/In press - 2024 |
Keywords
- WSe
- contact interlayer
- contact resistance
- scanning probe lithography
- selective-area doping
- short channel
- tungsten oxyselenide
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials