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Optical sensing nanostructures for porous silicon rugate filters.

Li S, Hu D, Huang J, Cai L - Nanoscale Res Lett (2012)

Bottom Line: Porous silicon rugate filters [PSRFs] and combination PSRFs [C-PSRFs] are emerging as interesting sensing materials due to their specific nanostructures and superior optical properties.A scanning electron microscope and a microfiber spectrophotometer were employed to analyze their physical structure and feature spectra, respectively.The C-PSRF sensors indicated the high sensitivity, quick response, perfect durability, reproducibility, and versatility in other organic gas sensing.

View Article: PubMed Central - HTML - PubMed

Affiliation: CAS Key Lab of Health Informatics, Shenzhen Key Laboratory of Cancer Nanotechnology, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Xueyuan Avenue 1068, Shenzhen University Town, Shenzhen, 518055, People's Republic of China. lt.cai@siat.ac.cn.

ABSTRACT
Porous silicon rugate filters [PSRFs] and combination PSRFs [C-PSRFs] are emerging as interesting sensing materials due to their specific nanostructures and superior optical properties. In this work, we present a systematic study of the PSRF fabrication and its nanostructure/optical characterization. Various PSRF chips were produced with resonance peaks that are adjustable from visible region to near-infrared region by simply increasing the periods of sine currents in a programmed electrochemical etching method. A regression analysis revealed a perfect linear correlation between the resonant peak wavelength and the period of etching current. By coupling the sine currents with several different periods, C-PSRFs were produced with defined multiple resonance peaks located at desired positions. A scanning electron microscope and a microfiber spectrophotometer were employed to analyze their physical structure and feature spectra, respectively. The sensing properties of C-PSRFs were investigated in an ethanol vapor, where the red shifts of the C-PSRF peaks had a good linear relationship with a certain concentration of ethanol vapor. As the concentration increased, the slope of the regression line also increased. The C-PSRF sensors indicated the high sensitivity, quick response, perfect durability, reproducibility, and versatility in other organic gas sensing.

No MeSH data available.


Related in: MedlinePlus

Cross-sectional view (a) and top view (b) of PSRF wafer FESEM images. The inset is a magnified cross-sectional view. (PSRF was prepared with a sinusoidal waveform ranging between 10 and 50 mA cm-2 with a period of 6.9 s for 30 cycles in a 3:1 (v/v) solution of 49% aqueous hydrofluoric acid and ethanol.)
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Figure 2: Cross-sectional view (a) and top view (b) of PSRF wafer FESEM images. The inset is a magnified cross-sectional view. (PSRF was prepared with a sinusoidal waveform ranging between 10 and 50 mA cm-2 with a period of 6.9 s for 30 cycles in a 3:1 (v/v) solution of 49% aqueous hydrofluoric acid and ethanol.)

Mentions: The PSRF structure was observed in various aspects using a FESEM. As can be seen from Figure 2a, the PSRF showed a sinusoidal-varying porosity gradient in the direction perpendicular to the plane of the filter, where the higher porosity film by high-current etching was in the dark zone, whereas the lower porosity film by low-current etching was located in the bright zone. The whole thickness for the stack layer of each sinusoidal period was about 285 nm on average. A magnified cross-sectional view (inset) revealed that the porous structure was made up of nanopores, where the inside walls of the nanopores were rather rough. Figure 2b showed the top view SEM image of the PSRF, where the pore sizes were 2 to 10 nm.


Optical sensing nanostructures for porous silicon rugate filters.

Li S, Hu D, Huang J, Cai L - Nanoscale Res Lett (2012)

Cross-sectional view (a) and top view (b) of PSRF wafer FESEM images. The inset is a magnified cross-sectional view. (PSRF was prepared with a sinusoidal waveform ranging between 10 and 50 mA cm-2 with a period of 6.9 s for 30 cycles in a 3:1 (v/v) solution of 49% aqueous hydrofluoric acid and ethanol.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3275543&req=5

Figure 2: Cross-sectional view (a) and top view (b) of PSRF wafer FESEM images. The inset is a magnified cross-sectional view. (PSRF was prepared with a sinusoidal waveform ranging between 10 and 50 mA cm-2 with a period of 6.9 s for 30 cycles in a 3:1 (v/v) solution of 49% aqueous hydrofluoric acid and ethanol.)
Mentions: The PSRF structure was observed in various aspects using a FESEM. As can be seen from Figure 2a, the PSRF showed a sinusoidal-varying porosity gradient in the direction perpendicular to the plane of the filter, where the higher porosity film by high-current etching was in the dark zone, whereas the lower porosity film by low-current etching was located in the bright zone. The whole thickness for the stack layer of each sinusoidal period was about 285 nm on average. A magnified cross-sectional view (inset) revealed that the porous structure was made up of nanopores, where the inside walls of the nanopores were rather rough. Figure 2b showed the top view SEM image of the PSRF, where the pore sizes were 2 to 10 nm.

Bottom Line: Porous silicon rugate filters [PSRFs] and combination PSRFs [C-PSRFs] are emerging as interesting sensing materials due to their specific nanostructures and superior optical properties.A scanning electron microscope and a microfiber spectrophotometer were employed to analyze their physical structure and feature spectra, respectively.The C-PSRF sensors indicated the high sensitivity, quick response, perfect durability, reproducibility, and versatility in other organic gas sensing.

View Article: PubMed Central - HTML - PubMed

Affiliation: CAS Key Lab of Health Informatics, Shenzhen Key Laboratory of Cancer Nanotechnology, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Xueyuan Avenue 1068, Shenzhen University Town, Shenzhen, 518055, People's Republic of China. lt.cai@siat.ac.cn.

ABSTRACT
Porous silicon rugate filters [PSRFs] and combination PSRFs [C-PSRFs] are emerging as interesting sensing materials due to their specific nanostructures and superior optical properties. In this work, we present a systematic study of the PSRF fabrication and its nanostructure/optical characterization. Various PSRF chips were produced with resonance peaks that are adjustable from visible region to near-infrared region by simply increasing the periods of sine currents in a programmed electrochemical etching method. A regression analysis revealed a perfect linear correlation between the resonant peak wavelength and the period of etching current. By coupling the sine currents with several different periods, C-PSRFs were produced with defined multiple resonance peaks located at desired positions. A scanning electron microscope and a microfiber spectrophotometer were employed to analyze their physical structure and feature spectra, respectively. The sensing properties of C-PSRFs were investigated in an ethanol vapor, where the red shifts of the C-PSRF peaks had a good linear relationship with a certain concentration of ethanol vapor. As the concentration increased, the slope of the regression line also increased. The C-PSRF sensors indicated the high sensitivity, quick response, perfect durability, reproducibility, and versatility in other organic gas sensing.

No MeSH data available.


Related in: MedlinePlus