Fast and efficient photodetection in nanoscale quantum-dot junctions.

Prins, Ferry; Buscema, Michele; Seldenthuis, Johannes S; Etaki, Samir; Buchs, Gilles; Barkelid, Maria; Zwiller, Val; Gao, Yunan et al. · Nano Lett · 2012

basic_science · Level V

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Abstract

We report on a photodetector in which colloidal quantum dots directly bridge nanometer-spaced electrodes. Unlike in conventional quantum-dot thin film photodetectors, charge mobility no longer plays a role in our quantum-dot junctions as charge extraction requires only two individual tunnel events. We find an efficient photoconductive gain mechanism with external quantum efficiencies of 38 electrons-per-photon in combination with response times faster than 300 ns. This compact device-architecture may open up new routes for improved photodetector performance in which efficiency and bandwidth do not go at the cost of one another.

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