Selective Electron Beam Patterning of Oxygen‐Doped WSe(2) for Seamless Lateral Junction Transistors

Surface charge transfer doping (SCTD) using oxygen plasma to form a p‐type dopant oxide layer on transition metal dichalcogenide (TMDs) is a promising doping technique for 2D TMDs field‐effect transistors (FETs). However, patternability of SCTD is a key challenge to effectively switch FETs. Herein, a simple method to selectively pattern degenerately p‐type (p(+))‐doped WSe(2) FETs via electron beam (e‐beam) irradiation is reported. The effect of the selective e‐beam irradiation is confirmed by the gate‐tunable optical responses of seamless lateral p(+)–p diodes. The OFF state of the devices by inducing trapped charges via selective e‐beam irradiation onto a desired channel area in p(+)‐doped WSe(2), which is in sharp contrast to globally p(+)‐doped WSe(2) FETs, is realized. Selective e‐beam irradiation of the PMMA‐passivated p(+)‐WSe(2) enables accurate control of the threshold voltage (V (th)) of WSe(2) devices by varying the pattern size and e‐beam dose, while preserving the low contact resistance. By utilizing hBN as the gate dielectric, high‐performance WSe(2) p‐FETs with a saturation current of −280 µA µm(−1) and on/off ratio of 10(9) are achieved. This study's technique demonstrates a facile approach to obtain high‐performance TMD p‐FETs by e‐beam irradiation, enabling efficient switching and patternability toward various junction devices.