title: Y-contacted high-performance n-type single-walled carbon nanotube field-effect transistors: scaling and comparison with Sc-contacted devices.
abstract: While it has been shown that scandium (Sc) can be used for making high-quality Ohmic contact to the conduction band of a carbon nanotube (CNT) and thus for fabricating high-performance n-type CNT field effect transistors (FETs), the cost for metal Sc is currently five times more expensive than that for gold and one thousand times more expensive than for yttrium (Y) which in many ways resembles Sc. In this Letter we show that near perfect contacts can be fabricated on single-walled CNTs (SWCNTs) using Y, and the Y-contacted CNT FETs outperform the Sc-contacted CNT FETs in many important aspects. Low-temperature measurements on Y-contacted devices reveal that linear output characteristics persist down to 4.3 K, suggesting that Y makes a perfect Ohmic contact with the conduction band of the CNT. Self-aligned top-gate devices have been fabricated, showing high performance approaching the theoretical limit of CNT-based devices. In particular a room temperature conductance of about 0.55G(0) (with G(0) = 4e(2)/h being the quantum conductance limit of the SWCNT), threshold swing of 73 mV/decade, electron mobility of 5100 cm(2)/V.s, and mean free length of up to 0.639 mum have been achieved. Gate length scaling behavior of the Y-contacted CNT FETs is also investigated, revealing a more favorable energy consumption and faster intrinsic speed scaling than that of the Si-based devices.
authors.affiliation: Department of Electronics, Key Laboratory for the Physics and Chemistry of Nanodevices, Peking University, Beijing 100871, China.
authors.forename: Li
authors.initials: L
authors.lastname: Ding
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Qingsheng
authors.initials: Q
authors.lastname: Zeng
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Wang
authors.forename: Tian
authors.initials: T
authors.lastname: Pei
authors.forename: Leijing
authors.initials: L
authors.lastname: Yang
authors.forename: Xuelei
authors.initials: X
authors.lastname: Liang
authors.forename: Jun
authors.initials: J
authors.lastname: Shen
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.forename: Rongli
authors.initials: R
authors.lastname: Cui
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Lian-Mao
authors.initials: LM
authors.lastname: Peng
mesh_terms: D004553:Electric Conductivity; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D008839:Microelectrodes; D036103:Nanotechnology / Q000295:instrumentation*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D012538:Scandium / Q000737:chemistry*; D014173:Transistors, Electronic; D015019:Yttrium / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D015019:Yttrium; D012538:Scandium