Optoelectronic mixing with high-frequency graphene transistors.

Montanaro, A; Wei, W; De Fazio, D; Sassi, U; Soavi, G; Aversa, P; Ferrari, A C; Happy, H et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

Graphene is ideally suited for optoelectronics. It offers absorption at telecom wavelengths, high-frequency operation and CMOS-compatibility. We show how high speed optoelectronic mixing can be achieved with high frequency (~20 GHz bandwidth) graphene field effect transistors (GFETs). These devices mix an electrical signal injected into the GFET gate and a modulated optical signal onto a single layer graphene (SLG) channel. The photodetection mechanism and the resulting photocurrent sign depend on the SLG Fermi level (E<sub>F</sub>). At low E<sub>F</sub> (<130 meV), a positive photocurrent is generated, while at large E<sub>F</sub> (>130 meV), a negative photobolometric current appears. This allows our devices to operate up to at least 67 GHz. Our results pave the way for GFETs optoelectronic mixers for mm-wave applications, such as telecommunications and radio/light detection and ranging (RADAR/LIDARs.).