Letter abstract
Nature Nanotechnology 4, 40 - 44 (2009)
Published online: 9 November 2008 | doi:10.1038/nnano.2008.313
Subject Categories: Electronic properties and devices | Nanoparticles | Photonic structures and devices
Fast, sensitive and spectrally tuneable colloidal-quantum-dot photodetectors
Jason P. Clifford1, Gerasimos Konstantatos1, Keith W. Johnston1, Sjoerd Hoogland1, Larissa Levina1 & Edward H. Sargent1
Abstract
Solution-processed semiconductors are compatible with a range of substrates, which enables their direct integration with organic circuits1, 2, microfluidics3, 4, optical circuitry1, 5 and commercial microelectronics. Ultrasensitive photodetectors based on solution-process colloidal quantum dots operating in both the visible and infrared have been demonstrated6, 7, but these devices have poor response times (on the scale of seconds) to changes in illumination, and rapid-response devices based on a photodiode architecture suffer from low sensitivity8. Here, we show that the temporal response of these devices is determined by two components—electron drift, which is a fast process, and electron diffusion, which is a slow process. By building devices that exclude the diffusion component, we are able to demonstrate a >1,000-fold improvement in the sensitivity–bandwidth product of tuneable colloidal-quantum-dot photodiodes operating in the visible and infrared6, 7, 8.
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada
Correspondence to: Edward H. Sargent1 e-mail: ted.sargent@utoronto.ca
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