Zirconium Nitride for Plasmonic Cloaking of Visible Nanowire Photodetectors
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Zirconium Nitride for Plasmonic Cloaking of Visible Nanowire Photodetectors Katherine Hansen 1 & Amartya Dutta 2 & Melissa Cardona 2,3 & Chen Yang 1,2 Received: 6 December 2019 / Accepted: 17 February 2020 # The Author(s) 2020
Abstract Light scattered by a photodetector disturbs the probing field, resulting in noise. Cloaking is an effective method to reduce this noise. Here we investigate theoretically an emerging plasmonic material, zirconium nitride (ZrN), as a plasmonic cloak for silicon (Si) nanowire-based photodetectors and compare it with a traditional plasmonic material, gold (Au). Using Mie formalism, we have obtained the scattering cancelation across the visible spectrum. We found that ZrN cloaks produce a significant decrease in the scattering from bare Si nanowires, which is 40% greater than that obtained with Au cloaks in the wavelength region of 400– 500 nm. The scattering cancelations become comparable at 550 nm, with Au providing a better scattering cancelation compared to ZrN over the wavelength region of 600–700 nm. To include the absorption and provide a measure of overall performance on noise reduction, a figure of merit (FOM), defined as the ratio of the absorption efficiency and the scattering efficiency of the cloaked nanowire to that of the bare Si nanowire, was calculated. We show that the optimized ZrN cloak provides up to 3 times enhancement of the FOM over a bare Si NW and a 60% improvement over an optimized Au-cloaked NW, in the wavelength region of 400–500 nm. An optimized Au-cloaked NW shows up to 17.69 times improvement in the wavelength region of 600– 700 nm over a bare Si NW and up to a 2.7 times improvement over an optimized ZrN-cloaked NW. We also predicted the optimal dimensions for the cloaked NWs with respect to the largest FOM at various wavelengths between 400 and 650 nm. Keywords Plasmonic cloaking . Zirconium nitride . Nanowires . Core-shell . Scattering cancelation . Emerging plasmonic materials
Introduction Photodetectors are utilized in many applications including sensing and imaging. In the pursuit of scaling down device sizes while maintaining high responsivity, short response time, and high photoconductive gain; semiconducting nanostructures, especially nanowires, have been studied and shown Katherine Hansen and Amartya Dutta contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11468-020-01145-3) contains supplementary material, which is available to authorized users. * Chen Yang [email protected] 1
Department of Chemistry, Boston University, Boston, MA 02215, USA
2
Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215, USA
3
Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
to be promising [1–3]. Semiconductor nanowires (NWs) show high light sensitivity due to the large surface area to volume ratio, as well as high photoconductive gain due to surface state promoted charge separation. Silicon is one of the most common visible light
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