High-Mobility Holes in Dual-Gated WSe2 Field-Effect Transistors

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• 作者：Hema C. P. Movva ; Amritesh Rai ; Sangwoo Kang ; Kyounghwan Kim ; Babak Fallahazad ; Takashi Taniguchi ; Kenji Watanabe ; Emanuel Tutuc ; Sanjay K. Banerjee
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：October 27, 2015
• 年：2015
• 卷：9
• 期：10
• 页码：10402-10410
• 全文大小：618K
• ISSN：1936-086X

文摘

We demonstrate dual-gated p-type field-effect transistors (FETs) based on few-layer tungsten diselenide (WSe₂) using high work-function platinum source/drain contacts and a hexagonal boron nitride top-gate dielectric. A device topology with contacts underneath the WSe₂ results in p-FETs with I_ON/I_OFF ratios exceeding 10⁷ and contacts that remain ohmic down to cryogenic temperatures. The output characteristics show current saturation and gate tunable negative differential resistance. The devices show intrinsic hole mobilities around 140 cm²/(V s) at room temperature and approaching 4000 cm²/(V s) at 2 K. Temperature-dependent transport measurements show a metal鈥搃nsulator transition, with an insulating phase at low densities and a metallic phase at high densities. The mobility shows a strong temperature dependence consistent with phonon scattering, and saturates at low temperatures, possibly limited by Coulomb scattering or defects.