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Proceedings Paper

Surface characterization of nanostructured 'black silicon' using impedance spectroscopy
Author(s): Wenqi Duan; Fatima Toor
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Paper Abstract

In this work, we utilize electrochemical impedance spectroscopy (EIS) to study the electronic characteristics of nanostructured silicon (Si) fabricated using the metal-assisted chemical etched (MACE) process. The nanostructured Si fabricated using the MACE process results in a density graded surface that reduces the broadband surface reflection of Si making it appear almost black, which coins it the name ‘black Si’ (bSi). We study two bSi samples prepared using varying MACE times (20s and 40s) and a reference bare silicon sample using EIS between 1 MHz and 1 Hz frequencies. At an illumination intensity created with the use of a tungsten lamp source calibrated to output an intensity of 1-Sun (1000 W/m2), the impedance behavior at bias potentials in both the forward and reverse bias ranging between -1 V and 1 V are studied. We also study the effect of illumination wavelength by using bandpass filters at 400 nm and 800 nm. The results indicate that the charge transfer resistance (Rct) decreases as the surface roughness of the electrodes increases and as the illumination wavelength increases. We also find that the constant phase element (CPE) impedance of the electrodes increases with increasing surface roughness. These results will guide our future work on high efficiency bSi solar cells.

Paper Details

Date Published: 15 September 2016
PDF: 9 pages
Proc. SPIE 9927, Nanoengineering: Fabrication, Properties, Optics, and Devices XIII, 992711 (15 September 2016); doi: 10.1117/12.2237093
Show Author Affiliations
Wenqi Duan, Univ. of Iowa (United States)
Fatima Toor, Univ. of Iowa (United States)

Published in SPIE Proceedings Vol. 9927:
Nanoengineering: Fabrication, Properties, Optics, and Devices XIII
Eva M. Campo; Elizabeth A. Dobisz; Louay A. Eldada, Editor(s)

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