Feng Li-ping, Jiang Wan-zhen, Su Jie, Zhou Lian-qun, Liu Zheng-tang
State Key Lab of Solidification Processing, College of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P. R. China.
Medical Micro and Nano-technology Departmen, CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu 215163, P. R. China.
Nanoscale. 2016 Mar 28;8(12):6507-13. doi: 10.1039/c6nr00380j.
The Schottky barrier has been detected in many field-effect transistors (FETs) based on transition metal dichalcogenide (TMD) semiconductors and has seriously affected the electronic properties of the devices. In order to decrease the Schottky barrier in WS2 FETs, novel Nb doping in WS2 monolayers has been performed and p-FETs based on Nb-doped WS2 (Nb(x)W(1-x)S2) monolayers as the active channel have been fabricated for the first time. The monolayer Nb0.15W0.85S2 p-FET has a drain current of 330 μA μm(-1), an impressive I(ON)/I(OFF) of 10(7), and a high effective hole mobility of ∼146 cm(2) V(-1) s(-1). The novel Nb doping in monolayer WS2 has eliminated the ambipolar behavior and reduced the Schottky barrier in WS2 FETs. The reduction of the Schottky barrier is ascribed to the hybridization between W 5d, Nb 4d and S 3p states near the EF and to the enhancement of the metallization of the contact between the Pd metal and monolayer Nb(x)W(1-x)S2 after Nb doping.
在许多基于过渡金属二卤化物（TMD）半导体的场效应晶体管（FET）中都检测到了肖特基势垒，这严重影响了器件的电子性能。为了降低WS2 FET中的肖特基势垒，首次在WS2单层中进行了新型Nb掺杂，并制备了基于Nb掺杂的WS2（Nb(x)W(1 - x)S2）单层作为有源沟道的p型FET。单层Nb0.15W0.85S2 p型FET的漏极电流为330 μA μm(-1)，令人印象深刻的I(ON)/I(OFF)为10(7)，有效空穴迁移率高达约146 cm(2) V(-1) s(-1)。单层WS2中的新型Nb掺杂消除了双极性行为，并降低了WS2 FET中的肖特基势垒。肖特基势垒的降低归因于费米能级附近W 5d、Nb 4d和S 3p态之间的杂化，以及Nb掺杂后Pd金属与单层Nb(x)W(1 - x)S2之间接触的金属化增强。
