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Updated: Jul 29, 2025

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating
Published on: April 12, 2018
p-Type Conversion of WS2 and WSe2 by Position-Selective Oxidation Doping and Its Application in Top Gate Transistors
Ryoichi Kato1, Haruki Uchiyama1,2, Tomonori Nishimura1
1Department of Materials Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
Abstract:
For the complementary operation of two-dimensional (2D) material-based field-effect transistors (FETs), high-performance p-type FETs are essential. In this study, we applied surface charge-transfer doping from WO, which has a large work function of ∼6.5 eV, selectively to the access region of WS2 and WSe2 by covering the channel region with h-BN. By reducing the Schottky barrier width at the contact and injecting holes into the valence band, the p-type conversion of intrinsically n-type trilayer WSe2 FET was successfully achieved. However, trilayer WS2 did not show clear p-type conversion because its valence band maximum is 0.66 eV lower than that of trilayer WSe2. Although inorganic WO boasts high air stability and fabrication process compatibility due to its high thermal budget, the trap sites in WO cause large hysteresis during back gate operation of WSe2 FETs. However, by using top gate (TG) operation with an h-BN protection layer as a TG insulator, a high-performance p-type WSe2 FET with negligible hysteresis was achieved.
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