Abstract
We report the fabrication of both n-type and p-type WSe2 field-effect transistors with hexagonal boron nitride passivated channels and ionic-liquid (IL)-gated graphene contacts. Our transport measurements reveal intrinsic channel properties including a metal-insulator transition at a characteristic conductivity close to the quantum conductance e2/h, a high ON/OFF ratio of >107 at 170 K, and large electron and hole mobility of μ ≈ 200 cm2 V-1s-1 at 160 K. Decreasing the temperature to 77 K increases mobility of electrons to ∼330 cm2 V-1 s-1 and that of holes to ∼270 cm2 V-1 s-1. We attribute our ability to observe the intrinsic, phonon-limited conduction in both the electron and hole channels to the drastic reduction of the Schottky barriers between the channel and the graphene contact electrodes using IL gating. We elucidate this process by studying a Schottky diode consisting of a single graphene/WSe2 Schottky junction. Our results indicate the possibility to utilize chemically or electrostatically highly doped graphene for versatile, flexible, and transparent low-resistance ohmic contacts to a wide range of quasi-2D semiconductors.
Original language | English |
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Pages (from-to) | 3594-3601 |
Number of pages | 8 |
Journal | Nano Letters |
Volume | 14 |
Issue number | 6 |
DOIs | |
State | Published - Jun 11 2014 |
Keywords
- Schottky barrier
- field-effect transistor
- graphene
- ionic-liquid gate