Highly Stable and Tunable Chemical Doping of Multilayer WS2 Field Effect Transistor: Reduction in Contact Resistance

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• 作者：Hafiz M. W. Khalil ; Muhammad Farooq Khan ; Jonghwa Eom ; Hwayong Noh
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：October 28, 2015
• 年：2015
• 卷：7
• 期：42
• 页码：23589-23596
• 全文大小：550K
• ISSN：1944-8252

文摘

The development of low resistance contacts to 2D transition-metal dichalcogenides (TMDs) is still a big challenge for the future generation field effect transistors (FETs) and optoelectronic devices. Here, we report a chemical doping technique to achieve low contact resistance by keeping the intrinsic properties of few layers WS<sub>2sub>. The transfer length method has been used to investigate the effect of chemical doping on contact resistance. After doping, the contact resistance (R<sub>csub>) of multilayer (ML) WS<sub>2sub> has been reduced to 0.9 k惟路渭m. The significant reduction of the R<sub>csub> is mainly due to the high electron doping density, thus a reduction in Schottky barrier height, which limits the device performance. The threshold voltage of ML-WS<sub>2sub> FETs confirms a negative shift upon the chemical doping, as further confirmed from the positions of E<sup>1sup><sub>2gsub> and A<sub>1gsub> peaks in Raman spectra. The n-doped samples possess a high drain current of 65 渭A/渭m, with an on/off ratio of 1.05 脳 10<sup>6sup> and a field effect mobility of 34.7 cm<sup>2sup>/(V路s) at room temperature. Furthermore, the photoelectric properties of doped WS<sub>2sub> flakes were also measured under deep ultraviolet light. The potential of using LiF doping in contact engineering of TMDs opens new ways to improve the device performance.