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While two-dimensional (2D) materials have shown great promise for scaling technology nodes beyond the limits of silicon devices, key challenges remain for realizing high quality and practical 2D field effect transistors (FETs), including lowering contact resistance, demonstrating device structures with high electrical stability and reduced interface charge trapping, and integrating n- and p-FETs for beyond-CMOS devices. High contact resistance often stems from Schottky contacts and Fermi level pinning, and can be reduced by local doping or transferred contacts, respectively. However, these approaches have so far been mutually incompatible. We demonstrate a locally-doped transferred contact device stack, where metal via contacts embedded in hexagonal boron nitride (hBN) contain a local access region through which otherwise fully encapsulated WSe2 channels are surface charge transfer doped by oxygen plasma treatment, creating a lateral p+–i–p+ junction FET. The geometry of gates, doped access regions, and the channel are all defined by electron beam lithograph giving full and precise control over size and position. The p-FET behavior is strongly enhanced with high on/off ratio up to 107, but ambipolar characteristics from the intrinsic channel are still retained. Negligible, temperature-independent hysteresis is achieved from T = 10 to 300 K, with only back gate carrier control. High electrical stability is evident in excellent reproducibility of transfer characteristics between multiple contact sets on a single device and different devices. The doping reduces contact resistance by reducing Schottky barrier height and width, achieving Ohmic IV characteristics. The doping appears very stable, with negligible degradation of performance keeping the device for 50 days in atmosphere. This relatively simple device structure incorporates two important strategies to improve con- tact quality, improving p-FET performance while retaining intrinsic ambipolar channel properties for applications integrating n- and p-FETs.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: 2D field-effect transistors, contact resistance, WSe2

刊行年月日: 2024-11-26

出版者: American Chemical Society (ACS)

掲載誌:

• ACS Applied Electronic Materials (ISSN: 26376113) vol. 6 issue. 11 p. 8319-8327

研究助成金:

• Ministry of Education, Culture, Sports, Science and Technology
• Japan Society for the Promotion of Science 21H05233
• Japan Society for the Promotion of Science 23H02052
• Taiwan Semiconductor Manufacturing Company
• National Science and Technology Council 111-2112-M-006-036-MY3
• Ministry of Education Taiwan

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1021/acsaelm.4c01574

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更新時刻: 2025-02-05 16:30:33 +0900

MDRでの公開時刻: 2025-02-05 16:30:33 +0900