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Two‐dimensional semiconductors are considered as promising candidates in next‐generation nanoelectronics. The polarity regulation, however, has been a great obstacle to their applications. Herein, a strategy to comprehensively modulate the polarity of WSe2 field‐effect transistors (FETs) by combining contact engineering and plasma doping is demonstrated. N‐type and ambipolar WSe2 FETs are obtained by indium (In) and chromium (Cr) contact, respectively. Meanwhile Cr contact and mild oxygen plasma doping are employed simultaneously to realize p‐type WSe2 FET. High on/off ratio of ≈107 has been achieved for both n‐type and p‐type WSe2 FETs. Subsequently, they are connected in series to construct a homogeneous complementary logic inverter and a lateral p–n diode. Anti‐ambipolar transfer characteristics, therefore, are accessed from the inverter. And the forward to backward rectifying ratio reaches 106 for the p–n diode. The proposed strategy paves the way for practical applications of WSe2 FETs in logic circuits and optoelectronics.

The performance of nanoelectronic devices can be significantly improved using high‐k dielectric materials. However, the interface between the gate dielectric and channel can impact the device's stability and performance. To address this issue, a new approach is developed that involves incorporating high‐k dielectric into the channel via in situ oxidation of air‐sensitive 2D materials. Herein, the impact of HfSe2 thermal oxidation on the electrical properties of the MoS2 channel is investigated. The findings demonstrate that incomplete oxidation of HfSe2 on the MoS2 channel introduces significant border traps, leading to device performance degradation. In contrast, complete oxidation of HfSe2 leads to the formation of high‐k HfOx. The MoS2 field‐effect transistors capped by in situ thermally oxidized HfOx show a twofold enhancement in field‐effect mobility and improved gate bias stress stability. These findings suggest that the integration of high‐k dielectrics via in situ oxidation has great potential for high‐performance electronic device applications.