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Roya Maboudian - One of the best experts on this subject based on the ideXlab platform.

  • OXIDATION MECHANISM OF THE Ammonium-Fluoride-TREATED SI(100) SURFACE
    Journal of Applied Physics, 1996
    Co-Authors: G. Jonathan Kluth, Roya Maboudian
    Abstract:

    High‐resolution electron energy loss (HREEL) spectroscopy, Auger electron spectroscopy, and low‐energy electron diffraction have been employed to examine the initial oxidation stage of Ammonium‐Fluoride‐treated Si(100) surfaces exposed to air. The NH4F treatment results in a hydrogen‐terminated surface, as shown by the presence of the Si–H stretch (2100 cm−1), SiH2 scissor (910 cm−1), and SiH bend (650 cm−1) in the HREEL spectra. Initial oxidation on this surface occurs through oxygen insertion in the silicon backbonds, as indicated by the presence of the asymmetric bridge‐bonded oxygen stretch in the region between 1060 and 1160 cm−1. Oxygen is observed in both surface and bulk bridge‐bonding sites for even the shortest air exposures, suggesting that initial oxygen uptake is not taking place in a layer‐by‐layer fashion. Auger electron spectroscopy shows a slow uptake of oxygen over the first few days of air exposure, followed by more rapid oxidation. Over the first two weeks of air exposure, the Si–H str...

  • Stability of Ammonium Fluoride‐treated Si(100)
    Journal of Applied Physics, 1995
    Co-Authors: Michael R. Houston, Roya Maboudian
    Abstract:

    X‐ray photoelectron spectroscopy (XPS) and contact angle analyses have been employed to investigate the chemical stability of silicon surfaces treated by an Ammonium Fluoride (NH4F) solution. Consistent with earlier results [Dumas and Chabal, Chem. Phys. Lett. 181, 537 (1991)], it is found that an NH4F final etch produces surfaces exhibiting lower oxygen and carbon contamination levels in comparison to the surfaces obtained with the traditional HF or buffered HF (BHF) etch. In conjunction with lower contamination levels, surfaces treated in Ammonium Fluoride show higher contact angles with water, indicating lower surface free energies. The Si‐H surfaces produced by the Ammonium Fluoride etch were found to remain hydrophobic for weeks in air and showed no signs of oxidation for several days. After an induction period of about one week in air, oxidation began to occur in a more rapid fashion. The stability of the Si‐H surfaces in water was also investigated, and it was found that the oxygen contamination le...

  • stability of Ammonium Fluoride treated si 100
    Journal of Applied Physics, 1995
    Co-Authors: Michael R. Houston, Roya Maboudian
    Abstract:

    X‐ray photoelectron spectroscopy (XPS) and contact angle analyses have been employed to investigate the chemical stability of silicon surfaces treated by an Ammonium Fluoride (NH4F) solution. Consistent with earlier results [Dumas and Chabal, Chem. Phys. Lett. 181, 537 (1991)], it is found that an NH4F final etch produces surfaces exhibiting lower oxygen and carbon contamination levels in comparison to the surfaces obtained with the traditional HF or buffered HF (BHF) etch. In conjunction with lower contamination levels, surfaces treated in Ammonium Fluoride show higher contact angles with water, indicating lower surface free energies. The Si‐H surfaces produced by the Ammonium Fluoride etch were found to remain hydrophobic for weeks in air and showed no signs of oxidation for several days. After an induction period of about one week in air, oxidation began to occur in a more rapid fashion. The stability of the Si‐H surfaces in water was also investigated, and it was found that the oxygen contamination le...

Michael R. Houston - One of the best experts on this subject based on the ideXlab platform.

  • Stability of Ammonium Fluoride‐treated Si(100)
    Journal of Applied Physics, 1995
    Co-Authors: Michael R. Houston, Roya Maboudian
    Abstract:

    X‐ray photoelectron spectroscopy (XPS) and contact angle analyses have been employed to investigate the chemical stability of silicon surfaces treated by an Ammonium Fluoride (NH4F) solution. Consistent with earlier results [Dumas and Chabal, Chem. Phys. Lett. 181, 537 (1991)], it is found that an NH4F final etch produces surfaces exhibiting lower oxygen and carbon contamination levels in comparison to the surfaces obtained with the traditional HF or buffered HF (BHF) etch. In conjunction with lower contamination levels, surfaces treated in Ammonium Fluoride show higher contact angles with water, indicating lower surface free energies. The Si‐H surfaces produced by the Ammonium Fluoride etch were found to remain hydrophobic for weeks in air and showed no signs of oxidation for several days. After an induction period of about one week in air, oxidation began to occur in a more rapid fashion. The stability of the Si‐H surfaces in water was also investigated, and it was found that the oxygen contamination le...

  • stability of Ammonium Fluoride treated si 100
    Journal of Applied Physics, 1995
    Co-Authors: Michael R. Houston, Roya Maboudian
    Abstract:

    X‐ray photoelectron spectroscopy (XPS) and contact angle analyses have been employed to investigate the chemical stability of silicon surfaces treated by an Ammonium Fluoride (NH4F) solution. Consistent with earlier results [Dumas and Chabal, Chem. Phys. Lett. 181, 537 (1991)], it is found that an NH4F final etch produces surfaces exhibiting lower oxygen and carbon contamination levels in comparison to the surfaces obtained with the traditional HF or buffered HF (BHF) etch. In conjunction with lower contamination levels, surfaces treated in Ammonium Fluoride show higher contact angles with water, indicating lower surface free energies. The Si‐H surfaces produced by the Ammonium Fluoride etch were found to remain hydrophobic for weeks in air and showed no signs of oxidation for several days. After an induction period of about one week in air, oxidation began to occur in a more rapid fashion. The stability of the Si‐H surfaces in water was also investigated, and it was found that the oxygen contamination le...

  • Ammonium Fluoride Anti-stiction Treatments For Polysilicon Microstructures
    Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95, 1
    Co-Authors: Michael R. Houston, R. Maboudian, R.t. Howe
    Abstract:

    A surface treatment for stiction reduction is described which has been shown to passivate surface micromachined micromechanical structures. Surface passivation is accomplished during the etching of silicon by Ammonium Fluoride (NH/sub 4/F) by means of a high quality hydrogen-termination of surface dangling bonds. The NH/sub 4/F treatment is integrated directly with the conventional release process, and is compatible with super critical drying techniques. Use of a cantilever beam array specifically designed for the measurement of in-use stiction showed a decrease in the work of adhesion from 42 mJ/m/sup 2/ for the hydrophilic release to less than, 0.3 mJ/m/sup 2/ for the NH/sub 4/F release processes. Encapsulation in a dry ambient will be necessary, as the hydrogen-terminated surface oxidizes after about one week in room air.

M. I. N. Isa - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of polyethylene glycol plasticized carboxymethyl cellulose-Ammonium Fluoride solid biopolymer electrolytes
    2017
    Co-Authors: M. A. Ramlli, M. A. Maksud, M. I. N. Isa
    Abstract:

    An attempt to increase the ionic conductivity of solid biopolymer electrolyte (SBE) from carboxyl methylcellulose (CMC) doped with 9 wt. % of Ammonium Fluoride (AF) has been made by the plasticizing with polyethylene glycol (PEG). Electrochemical Impedance Spectroscopy (EIS) was used to investigate the ionic conductivity of the CMC-AF-PEG SBEs. The study shows that the highest conductivity achieved is 6.62×10−7 S cm−1 at room temperature for SBE with 25 % wt. PEG. X-Ray Diffraction (XRD) study proved that the highest conductive SBE has the highest amorphous nature which contributes to the high conductivity of the SBE. The interaction of CMC and AF was enhanced by the addition of PEG at C-O band in the CMC.

  • structural and ionic transport properties of protonic conducting solid biopolymer electrolytes based on carboxymethyl cellulose doped with Ammonium Fluoride
    Journal of Physical Chemistry B, 2016
    Co-Authors: M. A. Ramlli, M. I. N. Isa
    Abstract:

    Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transference number measurement (TNM) techniques were applied to investigate the complexation, structural, and ionic transport properties of and the dominant charge-carrier species in a solid biopolymer electrolyte (SBE) system based on carboxymethyl cellulose (CMC) doped with Ammonium Fluoride (NH4F), which was prepared via a solution casting technique. The SBEs were partially opaque in appearance, with no phase separation. The presence of interactions between the host polymer (CMC) and the ionic dopant (NH4F) was proven by FT-IR analysis at the C–O band. XRD spectra analyzed using Origin 8 software disclose that the degree of crystallinity (χc%) of the SBEs decreased with the addition of NH4F, indicating an increase in the amorphous nature of the SBEs. Analysis of the ionic transport properties reveals that the ionic conductivity of the SBEs is dependent on the ionic mobility (μ) and diffusion of ions (D). TNM analysis confirms that the SB...

  • Ionic Conductivity and Structural Analysis of Carboxymethyl Cellulose Doped With Ammonium Fluoride as Solid Biopolymer Electrolytes
    American-Eurasian Journal of Sustainable Agriculture, 2015
    Co-Authors: M. A. Ramlli, K. H. Kamarudin, M. I. N. Isa
    Abstract:

    In the present work, a series of solid biopolymer electrolytes (SBEs) from carboxymethyl cellulose (CMC) doped with Ammonium Fluoride (NH4F) (0 - 13 wt. %) was successfully prepared by solution cast technique. SBE sample containing 9 wt.% NH4F was found to exhibit the highest ionic conductivity of 2.68 x 10 -7 Scm -1 at ambient temperature. XRD analysis revealed that the SBE samples containing NH4F salt to be semi-crystalline in nature. FTIR spectra showed that the interaction between CMC and NH4F has occurred in the polymersalt system and the CMC-NH4F SBE system was a proton conductor.

  • Proton conducting polymer electrolytes of methylcellulose doped Ammonium Fluoride: Conductivity and ionic transport studies
    International Journal of Physical Sciences, 2010
    Co-Authors: Noorizan Abd Aziz, N. K. Idris, M. I. N. Isa
    Abstract:

    Methylcellulose (MC) was used as polymer host and Ammonium Fluoride (AF) salt was used as the proton donor. A proton-conducting solid polymer electrolytes (SPE) was prepared by the solution casting method. The highest ionic conductivity at room temperature is 6.4 x 10-7 Scm-1. The ionic mobility and diffusion coefficient that was calculated in this work is in good agreement with the increment of weight percent (wt %) of acid concentration. The value of cation of diffusion coefficient and ionic mobility was higher than value of anion. Thus, the results proven that the present samples were proton conductor.   Key words: Methylcellulose, Ammonium Fluoride, polymer electrolyte, proton conductor, ionic transport.

M. A. Ramlli - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of polyethylene glycol plasticized carboxymethyl cellulose-Ammonium Fluoride solid biopolymer electrolytes
    2017
    Co-Authors: M. A. Ramlli, M. A. Maksud, M. I. N. Isa
    Abstract:

    An attempt to increase the ionic conductivity of solid biopolymer electrolyte (SBE) from carboxyl methylcellulose (CMC) doped with 9 wt. % of Ammonium Fluoride (AF) has been made by the plasticizing with polyethylene glycol (PEG). Electrochemical Impedance Spectroscopy (EIS) was used to investigate the ionic conductivity of the CMC-AF-PEG SBEs. The study shows that the highest conductivity achieved is 6.62×10−7 S cm−1 at room temperature for SBE with 25 % wt. PEG. X-Ray Diffraction (XRD) study proved that the highest conductive SBE has the highest amorphous nature which contributes to the high conductivity of the SBE. The interaction of CMC and AF was enhanced by the addition of PEG at C-O band in the CMC.

  • structural and ionic transport properties of protonic conducting solid biopolymer electrolytes based on carboxymethyl cellulose doped with Ammonium Fluoride
    Journal of Physical Chemistry B, 2016
    Co-Authors: M. A. Ramlli, M. I. N. Isa
    Abstract:

    Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transference number measurement (TNM) techniques were applied to investigate the complexation, structural, and ionic transport properties of and the dominant charge-carrier species in a solid biopolymer electrolyte (SBE) system based on carboxymethyl cellulose (CMC) doped with Ammonium Fluoride (NH4F), which was prepared via a solution casting technique. The SBEs were partially opaque in appearance, with no phase separation. The presence of interactions between the host polymer (CMC) and the ionic dopant (NH4F) was proven by FT-IR analysis at the C–O band. XRD spectra analyzed using Origin 8 software disclose that the degree of crystallinity (χc%) of the SBEs decreased with the addition of NH4F, indicating an increase in the amorphous nature of the SBEs. Analysis of the ionic transport properties reveals that the ionic conductivity of the SBEs is dependent on the ionic mobility (μ) and diffusion of ions (D). TNM analysis confirms that the SB...

  • Ionic Conductivity and Structural Analysis of Carboxymethyl Cellulose Doped With Ammonium Fluoride as Solid Biopolymer Electrolytes
    American-Eurasian Journal of Sustainable Agriculture, 2015
    Co-Authors: M. A. Ramlli, K. H. Kamarudin, M. I. N. Isa
    Abstract:

    In the present work, a series of solid biopolymer electrolytes (SBEs) from carboxymethyl cellulose (CMC) doped with Ammonium Fluoride (NH4F) (0 - 13 wt. %) was successfully prepared by solution cast technique. SBE sample containing 9 wt.% NH4F was found to exhibit the highest ionic conductivity of 2.68 x 10 -7 Scm -1 at ambient temperature. XRD analysis revealed that the SBE samples containing NH4F salt to be semi-crystalline in nature. FTIR spectra showed that the interaction between CMC and NH4F has occurred in the polymersalt system and the CMC-NH4F SBE system was a proton conductor.

Liubov A. Osminkina - One of the best experts on this subject based on the ideXlab platform.

  • Structural and Optical Properties of Silicon Nanowire Arrays Fabricated by Metal Assisted Chemical Etching With Ammonium Fluoride.
    Frontiers in chemistry, 2019
    Co-Authors: K. A. Gonchar, Veronika Y. Kitaeva, George A. Zharik, Andrei A. Eliseev, Liubov A. Osminkina
    Abstract:

    Here we report on the metal assisted chemical etching method of silicon nanowires (SiNWs) manufacturing, where the commonly used hydrofluoric acid (HF) has been successfully replaced with Ammonium Fluoride (NH4F). The mechanism of the etching process and the effect of the pH values of H2O2: NH4F solutions on the structural and optical properties of nanowires were studied in detail. By an impedance and Mott-Schottky measurements it was shown that silver-assisted chemical etching of silicon can be attributed to a facilitated charge carriers transport through Si/SiOx/Ag interface. It was shown that the shape of nanowires changes from pyramidal to vertical with pH decreasing. Also it was established that the length of SiNW arrays nonlinearly depends on the pH for the etching time of 10 minutes. A strong decrease of the tоtаl reflectance to 5-10 % was shown for all the studied samples at the wavelength less than 800 nm, in comparison with crystalline silicon substrate (с-Si). At the same time, the intensities of the interband photoluminescence and the Raman scattering of SiNWs are increased strongly in compare to c-Si value, and also they were depended on both the length and the shape of SiNW: the biggest values were for the long pyramidal nanowires. That can be explained by a strong light scattering and partial light localization in SiNWs. Hereby, arrays of SiNWs, obtained by using weakly toxic Ammonium Fluoride, have great potential for usage in photovoltaics, photonics, and sensorics.

  • Structural and Optical Properties of Silicon Nanowire Arrays Fabricated by Metal Assisted Chemical Etching With Ammonium Fluoride
    Frontiers Media S.A., 2019
    Co-Authors: K. A. Gonchar, Veronika Y. Kitaeva, George A. Zharik, Andrei A. Eliseev, Liubov A. Osminkina
    Abstract:

    Here we report on the metal assisted chemical etching method of silicon nanowires (SiNWs) manufacturing, where the commonly used hydrofluoric acid (HF) has been successfully replaced with Ammonium Fluoride (NH4F). The mechanism of the etching process and the effect of the pH values of H2O2: NH4F solutions on the structural and optical properties of nanowires were studied in detail. By an impedance and Mott-Schottky measurements it was shown that silver-assisted chemical etching of silicon can be attributed to a facilitated charge carriers transport through Si/SiOx/Ag interface. It was shown that the shape of nanowires changes from pyramidal to vertical with pH decreasing. Also it was established that the length of SiNW arrays non-linearly depends on the pH for the etching time of 10 min. A strong decrease of the total reflectance to 5–10% was shown for all the studied samples at the wavelength <800 nm, in comparison with crystalline silicon substrate (c-Si). At the same time, the intensities of the interband photoluminescence and the Raman scattering of SiNWs are increased strongly in compare to c-Si value, and also they were depended on both the length and the shape of SiNW: the biggest values were for the long pyramidal nanowires. That can be explained by a strong light scattering and partial light localization in SiNWs. Hereby, arrays of SiNWs, obtained by using weakly toxic Ammonium Fluoride, have great potential for usage in photovoltaics, photonics, and sensorics