Improved Contacts to MoS2 Transistors by Ultra-High Vacuum Metal Deposition

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• 作者：Chris D. English ; Gautam Shine ; Vincent E. Dorgan ; Krishna C. Saraswat ; Eric Pop
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：June 8, 2016
• 年：2016
• 卷：16
• 期：6
• 页码：3824-3830
• 全文大小：526K
• 年卷期：0
• ISSN：1530-6992

文摘

The scaling of transistors to sub-10 nm dimensions is strongly limited by their contact resistance (R_C). Here we present a systematic study of scaling MoS₂ devices and contacts with varying electrode metals and controlled deposition conditions, over a wide range of temperatures (80 to 500 K), carrier densities (10¹² to 10¹³ cm^–2), and contact dimensions (20 to 500 nm). We uncover that Au deposited in ultra-high vacuum (∼10^–9 Torr) yields three times lower R_C than under normal conditions, reaching 740 Ω·μm and specific contact resistivity 3 × 10^–7 Ω·cm², stable for over four months. Modeling reveals separate R_C contributions from the Schottky barrier and the series access resistance, providing key insights on how to further improve scaling of MoS₂ contacts and transistor dimensions. The contact transfer length is ∼35 nm at 300 K, which is verified experimentally using devices with 20 nm contacts and 70 nm contact pitch (CP), equivalent to the “14 nm” technology node.