Chopping Frequency Variation of Photoacoustic Amplitude from Porous Silicon

This paper shows the in‐situ study of the wetting process in Silicon during anodization process using an electrochemical Differential photoacoustic Cell (DPC). The Photoacoustic amplitude and phase signals were obtained for samples in air, ethanol, ethanol/HF and finally air. According to these results ethanol is responsible for a mechanical contact reducing the superficial tension and ethanol/HF produce the removing of the SiOx and SiO2species on the Silicon surface. It was found that the DPC is a powerful technique to study the wet surface before the formation of the porous silicon layer (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…1. This technique is a special configuration of the PA technique [4,11]. The purpose of this configuration is toimprove thesignal to noise ratio.…”

Section: Materials and Methods 21 Photoacoustic Signal Generationmentioning

confidence: 99%

Differential photoacoustic cell to study the wetting process during porous silicon formation

Espinosa-Arbeláez

Velázquez-Hernández

Petricioli-Carranco

et al. 2011

Phys. Status Solidi C

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“…In this arti-cle, photoacoustic (PA) spectroscopy [9] was performed to characterize the below-gap absorption of μc-Si films deposited on TCO films with various surface morphologies. PA spectroscopy, which is based on the detection of heat generated by light irradiation [9], can be applied to samples with various shapes, including bulk [9], thin films [10,11] and even light-scattering samples such as porous materials [12], flakes and particles [13]. In the present study, μc-Si flakes removed from different TCO surfaces were characterized by PA spectroscopy.…”

mentioning

confidence: 99%

“…PA spectroscopy using a microphone technique was carried out at room temperature [12]. The μc-Si flakes were carefully placed as a single layer on a quartz substrate inside a closed cell.…”

mentioning

confidence: 99%

Photoacoustic spectroscopy and electron spin resonance studies of defects in microcrystalline silicon thin films grown on rough surfaces

Toyama

Kurihara

Sobajima

et al. 2010

Phys. Status Solidi (c)

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Light trapping is a crucial technique for increasing the photocurrent of solar cells, particularly that of microcrystalline (μc‐Si) thin‐film solar cells. Transparent conductive oxides with rough surfaces such as Al‐doped ZnO (AZO) have been used extensively for this purpose. In general, the surface morphology influences the film growth and photovoltaic performance; on extremely rough surfaces the photovoltaic performance deteriorates. In this article, the experimental results of photoacoustic (PA) spectroscopy, performed on μc‐Si films deposited on various AZO surfaces, are presented as a function of AZO surface roughness σRMS, together with those derived from electron spin resonance. The amplitudes of the PA signals at 1.4 eV increased significantly when σRMS = 22 nm, a roughness where cracks were not observed in the μc‐Si. The amplitudes of the PA signals at 0.9 eV and the spin densities showed sigmoidal increases centered at a critical roughness of around 30 nm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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