• Legagneux, Pierre
• Montanaro, Alberto
• Forti, Stiven
• Mišeikis, Vaidotas
• Terrés, Bernat
• Giambra, Marco Angelo
• Romagnoli, Marco
• Piccinini, Giulia
• Hamidouche, Louiza
• Martini, Leonardo
• Marconi, Simone
• Ferrari, Andrea
• Koppens, Frank
• Sorianello, Vito
• Fabbri, Filippo
• Pezzini, Sergio
• Coletti, Camilla
• Goykhman, Ilya

Abstract

We report compact, scalable, high-performance, waveguide integrated graphene-based photodetectors (GPDs) for telecom and datacom applications, not affected by dark current. To exploit the photothermoelectric (PTE) effect, our devices rely on a graphene/polymer/graphene stack with static top split gates. The polymeric dielectric, poly(vinyl alcohol) (PVA), allows us to preserve graphene quality and to generate a controllable p-n junction. Both graphene layers are fabricated using aligned single-crystal graphene arrays grown by chemical vapor deposition. The use of PVA yields a low charge inhomogeneity ∼8 × 1010 cm-2 at the charge neutrality point, and a large Seebeck coefficient ∼140 μV K-1, enhancing the PTE effect. Our devices are the fastest GPDs operating with zero dark current, showing a flat frequency response up to 67 GHz without roll-off. This performance is achieved on a passive, low-cost, photonic platform, and does not rely on nanoscale plasmonic structures. This, combined with scalability and ease of integration, makes our GPDs a promising building block for next-generation optical communication devices.

Topics

• impedance spectroscopy
• polymer
• alcohol
• chemical vapor deposition
• aligned