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Title: In situ photoacoustic characterization for porous silicon growing: Detection principles

Abstract

There are a few methodologies for monitoring the in-situ formation of Porous Silicon (PS). One of the methodologies is photoacoustic. Previous works that reported the use of photoacoustic to study the PS formation do not provide the physical explanation of the origin of the signal. In this paper, a physical explanation of the origin of the photoacoustic signal during the PS etching is provided. The incident modulated radiation and changes in the reflectance are taken as thermal sources. In this paper, a useful methodology is proposed to determine the etching rate, porosity, and refractive index of a PS film by the determination of the sample thickness, using scanning electron microscopy images. This method was developed by carrying out two different experiments using the same anodization conditions. The first experiment consisted of growth of the samples with different etching times to prove the periodicity of the photoacoustic signal, while the second one considered the growth samples using three different wavelengths that are correlated with the period of the photoacoustic signal. The last experiment showed that the period of the photoacoustic signal is proportional to the laser wavelength.

Authors:
 [1];  [2];  [3];  [4];  [2]
  1. Posgrado en Ciencia e Ingeniería de Materiales, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México Campus Juriquilla, C.P. 76230 Querétaro, Qro. (Mexico)
  2. (Mexico)
  3. Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México Distrito Federal, C. P. 04510 (Mexico)
  4. Licenciatura en Ingeniería Física, Facultad de Ingeniería, Universidad Autónoma de Querétaro, C. P. 76010 Querétaro, Qro. (Mexico)
Publication Date:
OSTI Identifier:
22596969
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 119; Journal Issue: 18; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ANODIZATION; DETECTION; ELECTRON SCANNING; ETCHING; FILMS; GROWTH; IMAGES; LASERS; PERIODICITY; POROSITY; POROUS MATERIALS; REFRACTIVE INDEX; SCANNING ELECTRON MICROSCOPY; SIGNALS; SILICON; THICKNESS; WAVELENGTHS

Citation Formats

Ramirez-Gutierrez, C. F., Licenciatura en Ingeniería Física, Facultad de Ingeniería, Universidad Autónoma de Querétaro, C. P. 76010 Querétaro, Qro., Castaño-Yepes, J. D., Rodriguez-García, M. E., E-mail: marioga@fata.unam.mx, and Departamento de Nanotecnología, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México Campus Juriquilla, C.P. 76230 Querétaro, Qro. In situ photoacoustic characterization for porous silicon growing: Detection principles. United States: N. p., 2016. Web. doi:10.1063/1.4948946.
Ramirez-Gutierrez, C. F., Licenciatura en Ingeniería Física, Facultad de Ingeniería, Universidad Autónoma de Querétaro, C. P. 76010 Querétaro, Qro., Castaño-Yepes, J. D., Rodriguez-García, M. E., E-mail: marioga@fata.unam.mx, & Departamento de Nanotecnología, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México Campus Juriquilla, C.P. 76230 Querétaro, Qro. In situ photoacoustic characterization for porous silicon growing: Detection principles. United States. doi:10.1063/1.4948946.
Ramirez-Gutierrez, C. F., Licenciatura en Ingeniería Física, Facultad de Ingeniería, Universidad Autónoma de Querétaro, C. P. 76010 Querétaro, Qro., Castaño-Yepes, J. D., Rodriguez-García, M. E., E-mail: marioga@fata.unam.mx, and Departamento de Nanotecnología, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México Campus Juriquilla, C.P. 76230 Querétaro, Qro. 2016. "In situ photoacoustic characterization for porous silicon growing: Detection principles". United States. doi:10.1063/1.4948946.
@article{osti_22596969,
title = {In situ photoacoustic characterization for porous silicon growing: Detection principles},
author = {Ramirez-Gutierrez, C. F. and Licenciatura en Ingeniería Física, Facultad de Ingeniería, Universidad Autónoma de Querétaro, C. P. 76010 Querétaro, Qro. and Castaño-Yepes, J. D. and Rodriguez-García, M. E., E-mail: marioga@fata.unam.mx and Departamento de Nanotecnología, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México Campus Juriquilla, C.P. 76230 Querétaro, Qro.},
abstractNote = {There are a few methodologies for monitoring the in-situ formation of Porous Silicon (PS). One of the methodologies is photoacoustic. Previous works that reported the use of photoacoustic to study the PS formation do not provide the physical explanation of the origin of the signal. In this paper, a physical explanation of the origin of the photoacoustic signal during the PS etching is provided. The incident modulated radiation and changes in the reflectance are taken as thermal sources. In this paper, a useful methodology is proposed to determine the etching rate, porosity, and refractive index of a PS film by the determination of the sample thickness, using scanning electron microscopy images. This method was developed by carrying out two different experiments using the same anodization conditions. The first experiment consisted of growth of the samples with different etching times to prove the periodicity of the photoacoustic signal, while the second one considered the growth samples using three different wavelengths that are correlated with the period of the photoacoustic signal. The last experiment showed that the period of the photoacoustic signal is proportional to the laser wavelength.},
doi = {10.1063/1.4948946},
journal = {Journal of Applied Physics},
number = 18,
volume = 119,
place = {United States},
year = 2016,
month = 5
}
  • Pulsed-laser photoacoustic spectroscopy (LPAS) can be used to nondestructively assay aqueous Cr(VI) concentrations at trace levels. The technique involves the absorption of light pulses at 371 nm by Cr(VI) species (predominately chromate and bichromate). The absorbed energy is subsequently released in the form of heat generating a local pressure wave that is detected by an ultrasonic transducer. Because the total absorptivity of a Cr(VI) solution depends on the mixture of Cr(VI) species present and, thus, is strongly correlated with pH, a simple working expression relating solution absorbance to pH was developed, and molar absorptivities for several Cr(VI) species are reported.more » The detection limit for Cr(VI), which is effectively determined by the absorptivity of water, is reported to be 1 ng mL{sup {minus}1} at pH 6. Detection limits near 0.3 ng mL{sup {minus}1} would be expected for solutions at pH 8 and above, where the absorptivities of Cr(VI) species are greater. The nondestructive nature of this technique makes {ital in situ} studies of trace-level Cr(VI) chemistry in small volumes possible. We show how the technique can be used to study, in essentially real time, the thermodynamics and kinetics of Cr(VI) sorption by hematite ({alpha}-Fe{sub 2}O{sub 3}) powder, and the effect of competing ions, such as phosphate, on these properties. {copyright} {ital 1999} {ital Society for Applied Spectroscopy}« less
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