Intrinsic rectification in gated CVD graphene ribbons
(2017) Graphene Barcelona 2017 — Location: Barcelona, Spain (28.March.2017)
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- THz rectennas couple micron-size antennas and high-speed diodes to convert the incoming THz AC electric field to useable DC power. The non-linear electrical behavior required for rectification can be obtained from metal/insulator/metal (MIM) diodes [1]. These however present frequency limitations due to poor intrinsic RC response time and impedance matching. Geometric graphene diodes have been proposed to address these issues [2]. The ballistic transport of charge carriers in a funnel-shaped planar structure, with a funnel neck width smaller than the mean free path, has been discussed to induce a diode-like asymmetric electrical behavior. Electrical results on the I-V asymmetry ϒ=|IDS(+VDS)/IDS(-VDS)| of these diodes have been reported with exfoliated graphene [2]. Here we investigate rectangular graphene ribbon FETs with the methodology described in [2] and report non-linear electrical characteristics without the particular funnel-shaped channel. Commercially available CVD graphene is transferred on wafer-scale from its Cu catalyst to a thermally grown 20 nm-thick silicon dioxide layer on a lightly-doped silicon substrate with an aluminum back-gate (Fig. 1). The 3 μm long and 30 μm wide graphene channels are defined and contacted using optical lithography. Kelvin probe DC measurements are performed at room temperature and at 77 K under vacuum conditions and exhibit a gate-controlled diode-like asymmetric behavior between forward and reverse biases of the same amplitude as reported by [2] (Fig. 2) at both temperatures. The results are explained by SPICE simulations and related to the slight change in graphene conductivity due to the VDG voltage variations. This may be of interest for graphene interconnect considerations as well as circuit designs using graphene FETs.
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Haddad, P.-A., Flandre, D., & Raskin, J.-P. (2017). Intrinsic rectification in gated CVD graphene ribbons. Proceedings of Graphene Barcelona 2017, p. paper #19. https://hdl.handle.net/2078.5/226869