Abstract
Graphene-based van der Waals heterostructures are promising building blocks for broadband photodetection because of the gapless nature of graphene. However, their performance is mostly limited by the inevitable trade-off between low dark current and photocurrent generation. Here, we demonstrate a hybrid photodetection mode based on the photogating effect coupled with the photovoltaic effect via tunable quantum tunneling through the unique graphene/Bi2Se3 heterointerface. The tunneling junction formed between the semimetallic graphene and the topologically insulating Bi2Se3 exhibits asymmetric rectifying and hysteretic current–voltage characteristics, which significantly suppresses the dark current and enhances the photocurrent. The photocurrent-to-dark current ratio increases by about a factor of 10 with the electrical tuning of tunneling resistance for efficient light detection covering the major photonic spectral band from the visible to the mid-infrared ranges. Our findings provide a novel concept of using tunable quantum tunneling for highly sensitive broadband photodetection in mixed-dimensional van der Waals heterostructures.
Highlights
Light detection over a wide spectral range, from the visible to the mid-infrared, has a great potential for numerous photonic and optoelectronic applications
Graphene can provide a versatile platform for broadband photodetection due to its gapless electronic band structure.[1−4] its low absorption and fast recombination of photogenerated carriers result in low photocurrent with comparably large dark current.[5−7] These limitations present major challenges, restraining the practical applications of photodetectors based on graphene
In graphene-based van der Waals heterostructures, semiconducting two-dimensional transition-metal dichalcogenide materials are typically used as they exhibit superior light−matter interaction properties that allow for enhanced light absorption
Summary
Light detection over a wide spectral range, from the visible to the mid-infrared, has a great potential for numerous photonic and optoelectronic applications. This is similar to the current silicon technology, where naturally formed silica plays a key role Another novelty of our work is describing the transition of charge carrier transport mechanisms through the graphene/Bi2Se3 interface, which is essential for coupling between photogating and photovoltaic effects. I−V curves in graphene/Bi2Se3 heterojunction is first observed in this work, implying the trapping of charge carriers at the interface This observation suggests that the trap-assisted photogating effect heterochannel by can be trapping ionfdupcheodtoignentehreategdrapchaerrnieer/sB,4i72−Se493 which can be coupled with the photovoltaic effect to effectively enhance the photocurrent owing to the rectifying tunneling junction.[5−7]
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