Digital logic circuits are based on complementary pairs of n- and p-type field effect transistors (FETs) via complementary metal oxide semiconductor (CMOS) technology. In three dimensional (3D or bulk) semiconductors, substitutional doping of acceptor or donor impurities is used to achieve p- and n-type FETs. However, the controllable p-type doping of low-dimensional semiconductors such as two-dimensional transition metal dichalcogenides (2D TMDs) has proved to be challenging. Although it is possible to achieve high quality, low resistance n-type van der Waals (vdW) contacts on 2D TMDs^1–5, obtaining p-type devices from evaporating high work function metals onto 2D TMDs has not been realised so far. Here we report high-performance p-type devices on single and few-layered molybdenum disulphide (MoS₂) and tungsten diselenide (WSe₂) based on industry-compatible electron beam evaporation of high work function metals such as Pd and Pt. Using atomic resolution imaging and spectroscopy, we demonstrate near ideal vdW interfaces without chemical interactions between the 2D TMDs and 3D metals. Electronic transport measurements reveal that the Fermi level is unpinned and p-type FETs based on vdW contacts exhibit low contact resistance of 3.3 kΩ·µm, high mobility values of ~ 190 cm²-V^-1s^-1 at room temperature with saturation currents in excess of > 10^-5 Amperes per micron (A-μm^-1) and on/off ratio of 10⁷. We also demonstrate an ultra-thin photovoltaic cell based on n- and p-type vdW contacts with an open circuit voltage of 0.6 V and power conversion efficiency of 0.82%.

数字逻辑电路基于通过互补金属氧化物半导体 (CMOS) 技术互补的 n 型和 p 型场效应晶体管 (FET) 对。在三维（3D 或体）半导体中，使用受主或施主杂质的替代掺杂来实现 p 型和 n 型 FET。然而，二维过渡金属二硫属化物（2D TMD）等低维半导体的可控p型掺杂已被证明具有挑战性。^{尽管可以在 2D TMD 1-5}上实现高质量、低电阻的 n 型范德华 (vdW) 接触，但迄今为止尚未实现通过将高功函数金属蒸发到 2D TMD 上来获得 p 型器件。在这里，我们报告了单层和多层二硫化钼 ( _MoS2）和二硒化钨（WSe ₂）基于工业兼容的高功函数金属（如 Pd 和 Pt）电子束蒸发。使用原子分辨率成像和光谱学，我们展示了近乎理想的 vdW 界面，2D TMD 和 3D 金属之间没有化学相互作用。电子传输测量表明，费米能级是无钉扎的，并且基于 vdW 接触的 p 型 FET在室温和饱和电流下表现出 3.3 kΩ·μm 的低接触电阻和 ~ 190 cm 2 -V -1 s -1^的高^迁移率^值超过 > 10 ^-5安培每微米 (A-μm ^-1 ) 且开/关比为 10 ⁷。我们还展示了一种基于 n​​ 型和 p 型 vdW 接触的超薄光伏电池，其开路电压为 0.6 V，功率转换效率为 0.82%。