Terahertz photoconductivity in bilayer graphene transistors: evidence for tunneling at gate-induced junctions

Abstract

Photoconductivity of novel materials is the key property of interest for design of photodetectors, optical modulators, and switches. Despite the photoconductivity of most novel 2d materials has been studied both theoretically and experimentally, the same is not true for 2d p-n junctions that are necessary blocks of most electronic devices. Here, we study the sub-terahertz photocoductivity of gapped bilayer graphene with electrically-induced p-n junctions. We find a strong positive contribution from junctions to resistance, temperature resistance coefficient and photo-resistivity at cryogenic temperatures T ~ 20 K. The contribution to these quantities from junctions exceeds strongly the bulk values at uniform channel doping even at small band gaps ~ 10 meV. We further show that positive junction photoresistance is a hallmark of interband tunneling, and not of intra-band thermionic conduction. Our results point to the possibility of creating various interband tunneling devices based on bilayer graphene, including steep-switching transistors and selective sensors.

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Cited by in corpus (7)

• Roadmap for Photonics with 2D Materials
• Ultralow-noise terahertz detection by p-n junctions in gapped bilayer graphene
• Zero-bias photodetection in 2d materials via geometric design of contacts
• Anomalous terahertz photoconductivity caused by the superballistic flow of hydrodynamic electrons in graphene
• Enhanced Terahertz Photoresponse via Acoustic Plasmon Cavity Resonances in Scalable Graphene
• Mode-selective cloaking and phase-matching cavity resonances in bilayer graphene transport
• Selective damping of plasmons in coupled two-dimensional systems by Coulomb drag