Direct evidence of O2-plasma induced contact metal Fermi-level realignment is observed in WSe2 based SB field-effect transistors (FETs), leading to high hole currents with on/off ratios >108. The formation of tungsten oxide (WOx) converted from top WSe2 layers not only serves as an effective p-type dopant, but also unpins the Fermi-level of the metal contacts. The phenomena are corroborated by significant threshold voltage shifts, improved hole currents and suppression of the electron branch, observed from our statistical device characteristics. In addition, channel thickness dependence is investigated with the observation of complete suppression of the electron branch in thin WSe2 (< 4.9nm) devices after the O2-plasma treatment, which is interpreted as more substantial increase of SB height to the conduction band of larger bandgaps. Excellent air-stability is also concluded from statistical device results, suggesting a robust p-doping approach for WSe2 through O2-plasma treatment.

中文翻译：

---

用于具有 > 10 8 开/关比的单极和高空穴电流 WSe2 器件的掺杂诱导肖特基势垒重新排列

在基于 WSe2 的 SB 场效应晶体管 (FET) 中观察到 O2 等离子体诱导接触金属费米能级重新排列的直接证据，导致开/关比 >108 的高空穴电流。从顶部 WSe2 层转化的氧化钨 (WOx) 的形成不仅可以作为有效的 p 型掺杂剂，而且还可以解除金属触点的费米能级。从我们的统计器件特性中观察到的显着阈值电压偏移、改进的空穴电流和电子分支的抑制证实了该现象。此外，通过观察在 O2 等离子体处理后薄 WSe2 (< 4.9nm) 器件中电子分支的完全抑制，研究了沟道厚度依赖性，这被解释为 SB 高度增加到更大的导带。带隙。