Nanoprinted Quantum Dots-Graphene lnfrared Photodetectors
Matthias J. Grotevent a b, Claudio Hail c, Sergii Yakunin a d, Dmitry N. Dirin a d, Kishan Thodkar b, Gabriela Borin Barin e, Philippe Guyot-Sionnest f, Michel Calame b g, Dimos Poulikakos c, Maksym V. Kovalenko a d, Ivan Shorubalko b
a Laboratory of Inorganic Chemistry, Department of Chemistry & Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg, 1, Zürich, Switzerland
b Empa – Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Transport at Nanoscale Interfaces, Dübendorf, Switzerland, Switzerland
c Laboratory of Thermodynamics in Emerging Technologies, ETH Zürich, Switzerland, Sonneggstrasse, 3, Zürich, Switzerland
d Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland, Überland Strasse, 129, Dübendorf, Switzerland
e Nanotech at Surfaces, Empa, Switzerland, 8600 Dübendorf, Suiza, Dübendorf, Switzerland
f James Frank Institute, University of Chicago, USA
g Swiss Nanoscience Institute, University of Basel, Switzerland, Switzerland
Proceedings of Internet Conference for Quantum Dots (iCQD)
Online, Spain, 2020 July 14th - 17th
Organizers: Quinten Akkerman, Raffaella Buonsanti, Zeger Hens and Maksym Kovalenko
Poster, Matthias J. Grotevent, 088
Publication date: 3rd July 2020
ePoster: 

Infrared light (IR) detection is applied for night vision and spectroscopy, but the fabrication costs of highly sensitive IR detectors limit their entry into society driven fields such as autonomous driving and the development of micro-spectrometers. State-of-the-art narrow bandgap infrared photodetectors suffer from expensive material growth, and incompatibility with silicon-based read-out electronics. Novel device concepts such as graphene field-effect transistors sensitized with colloidal quantum dots (QDs) exhibit high photoresponsivities in combination with facile materials syntheses. The spectral sensitivity of the detector is defined by the QDs material and QDs size, which can readily be altered. For multi-color photodetector arrays (micro-spectrometers), one concept is the division of pixels into sub-pixels, which differ in spectral sensitivity. This requires high precision of QDs thin film deposition. Here, we deposit the QDs material with electrohydrodynamic nanoprinting on top of graphene field-effect transistors. We demonstrate sub-micrometer feature sizes by nanoprinting PbS QDs on graphene and, therefore, the fabrication of sub-micrometer sized detectors is potentially possible. We investigated 5 µm wide and 50 µm long detectors in order to avoid potential problems arising from the proximity of the source-drain electrodes. Six detectors were fabricated varying the thickness of the PbS QDs layer from 90 to 170 nm, and we observed an increase of photoresponsivity up to a QDs layer thickness of 150 nm, while the noise-current was found to be independent of the QDs layer thickness. The resulting specific detectivities were at least 109 Jones at 1200 nm. The noise-current and the photoresponsivity are both linearly dependent on the drain current, therefore, lower drain voltages can be applied reducing the detector's power consumption.

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