Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK.
Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.
Nature. 2022 Oct;610(7930):61-66. doi: 10.1038/s41586-022-05134-w. Epub 2022 Aug 1.
Digital logic circuits are based on complementary pairs of n- and p-type field effect transistors (FETs) via complementary metal oxide semiconductor 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 (2D) transition-metal dichalcogenides (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, obtaining p-type devices by evaporating high-work-function metals onto 2D TMDs has not been realized so far. Here we report high-performance p-type devices on single- and few-layered molybdenum disulfide and tungsten diselenide based on industry-compatible electron beam evaporation of high-work-function metals such as palladium and platinum. 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 approximately 190 cmVs at room temperature, saturation currents in excess of 10 A μm and an on/off ratio of 10. 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 a power conversion efficiency of 0.82%.
数字逻辑电路基于互补对的 n 型和 p 型场效应晶体管（FET），通过互补金属氧化物半导体技术实现。在三维（3D）或体半导体中，通过替代掺杂受主或施主杂质来实现 p 型和 n 型 FET。然而，对于二维（2D）过渡金属二卤化物（TMD）等低维半导体的可控 p 型掺杂已被证明具有挑战性。尽管有可能在 2D TMD 上实现高质量、低电阻的 n 型范德华（vdW）接触，但迄今为止，通过将高功函数金属蒸发到 2D TMD 上获得 p 型器件尚未实现。在这里，我们报告了基于工业兼容的电子束蒸发高功函数金属（如钯和铂）的单层和少层二硫化钼和二硒化钨的高性能 p 型器件。通过原子分辨率成像和光谱学，我们证明了在 2D TMD 和 3D 金属之间没有化学相互作用的近乎理想的 vdW 界面。电子输运测量表明费米能级未钉扎，基于 vdW 接触的 p 型 FET 具有低接触电阻 3.3 kΩµm、室温下约为 190 cmVs 的高迁移率值、超过 10 A µm 的饱和电流和 10 的导通/关断比。我们还展示了基于 n 型和 p 型 vdW 接触的超薄膜光伏电池，其开路电压为 0.6 V，功率转换效率为 0.82%。
