Hybrid graphene-quantum dot phototransistors with ultrahigh gain |
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Authors: | Konstantatos Gerasimos Badioli Michela Gaudreau Louis Osmond Johann Bernechea Maria Garcia de Arquer F Pelayo Gatti Fabio Koppens Frank H L |
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Affiliation: | ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Barcelona, Spain. gerasimos.konstantatos@icfo.es |
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Abstract: | Graphene is an attractive material for optoelectronics and photodetection applications because it offers a broad spectral bandwidth and fast response times. However, weak light absorption and the absence of a gain mechanism that can generate multiple charge carriers from one incident photon have limited the responsivity of graphene-based photodetectors to ~10(-2)?A?W(-1). Here, we demonstrate a gain of ~10(8) electrons per photon and a responsivity of ~10(7)?A?W(-1) in a hybrid photodetector that consists of monolayer or bilayer graphene covered with a thin film of colloidal quantum dots. Strong and tunable light absorption in the quantum-dot layer creates electric charges that are transferred to the graphene, where they recirculate many times due to the high charge mobility of graphene and long trapped-charge lifetimes in the quantum-dot layer. The device, with a specific detectivity of 7?×?10(13) Jones, benefits from gate-tunable sensitivity and speed, spectral selectivity from the short-wavelength infrared to the visible, and compatibility with current circuit technologies. |
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