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Issue 18, 2015
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Hybrid light sensor based on ultrathin Si nanomembranes sensitized with CdSe/ZnS colloidal nanocrystal quantum dots

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Abstract

We report the observation of a large enhancement of the wavelength-dependent photocurrent in ultrathin silicon nanomembranes (SiNM) decorated with colloidal CdSe/ZnS nanocrystal quantum dots (NQDs). Back-gated, field-effect transistor structures based on 75 nm-thick SiNMs are functionalized with self-assembled monolayers (SAMs) preventing surface oxidation and minimizing the surface defect densities. NQDs are drop cast on the active region of the device and the photocurrent is measured as a function of the excitation wavelength across the NQD absorption region. Photocurrent enhancement on the order of several hundred nA's is observed for NQD/SAM/SiNM devices compared to reference SAM/SiNM structures, with the device peak response closely correlated to the NQD absorption peak. We propose light-induced gating of the surface electrostatic potential and forward self-biasing of the FET channel as the two key mechanisms leading to the large photocurrent increase. Our findings open the possibility of employing silicon-nanocrystal hybrid structures for light sensing applications.

Graphical abstract: Hybrid light sensor based on ultrathin Si nanomembranes sensitized with CdSe/ZnS colloidal nanocrystal quantum dots

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Supplementary files

Article information


Submitted
16 Jan 2015
Accepted
11 Apr 2015
First published
14 Apr 2015

Nanoscale, 2015,7, 8524-8530
Article type
Paper
Author version available

Hybrid light sensor based on ultrathin Si nanomembranes sensitized with CdSe/ZnS colloidal nanocrystal quantum dots

W. Peng, S. Sampat, S. M. Rupich, B. Anand, H. M. Nguyen, D. Taylor, B. E. Beardon, Y. N. Gartstein, Y. J. Chabal and A. V. Malko, Nanoscale, 2015, 7, 8524
DOI: 10.1039/C5NR00334B

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