High-Performance Two-Dimensional Electronics with a Noncontact Remote Doping Method.

Ho, Po-Hsun; Cheng, Ren-Hao; Pao, Po-Heng; Chou, Sui-An; Huang, Yi-Hsiu; Yang, Yu-Ying; Wu, Yu-Syuan; Su, Yuan-Chun et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

Because of the intrinsic low carrier density of monolayer two-dimensional (2D) materials, doping is crucial for the performance of underlap top-gated 2D devices. However, wet etching of a high-<i>k</i> (dielectric constant) dielectric layer is difficult to implement without causing performance deterioration on the devices; therefore, finding a suitable spacer doping technique for 2D devices is indispensable. In this study, we developed a remote doping (RD) method in which defective SiO<sub><i>x</i></sub> can remotely dope the underlying high-<i>k</i> capped 2D regions without directly contacting these materials. This method achieved a doping density as high as 1.4 × 10<sup>13</sup> cm<sup>-2</sup> without reducing the mobility of the doped materials; after 1 month, the doping concentration remained as high as 1.2 × 10<sup>13</sup> cm<sup>-2</sup>. Defective SiO<sub><i>x</i></sub> can be used to dope most popular 2D transition-metal dichalcogenides. The low-<i>k</i> properties of SiO<sub><i>x</i></sub> render it ideal for spacer doping, which is very attractive from the perspective of circuit operation. In our experiments, MoS<sub>2</sub> and WS<sub>2</sub> underlap top-gate devices exhibited 10× and 200× increases in their on-currents, respectively, after being doped with SiO<i><sub>x</sub></i>. These results indicate that SiO<i><sub>x</sub></i> doping can be conducted to manufacture high-performance 2D devices.