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.
@article{arxiv.1211.0456,
title = {Fast and efficient photodetection in nanoscale quantum-dot junctions},
author = {Ferry Prins and Michele Buscema and Johannes S. Seldenthuis and Samir Etaki and Gilles Buchs and Maria Barkelid and Val Zwiller and Yunan Gao and Arjan J. Houtepen and Laurens D. A. Siebbeles and Herre S. J. van der Zant},
journal= {arXiv preprint arXiv:1211.0456},
year = {2012}
}