Papers by Author: M. Rusop

Abstract: Mist-atomization deposition method was applied in order to grow ZnO nanoparticles on Au-seeded glass substrates acting as seeded template. Ag doped ZnO thin films were deposited on ZnO seeded templates by solution-immersion method. The influence of Ag doping content on the optical and Raman scattering properties of ZnO films were systematically investigated by UV-Vis transmittance measurement measured by ultra-violet visible spectroscopy (UV-Vis) and Raman scattering spectrum measured by Raman spectroscopy under room temperature. From UV-Vis transmittance measurement, the incorporation of Ag dopant to the ZnO makes the transmittance wavelength shifted to the shorter wavelength as compared to the pure ZnO. From Raman spectra, 4 cm^-1 downshift is observed in Ag-doped thin films as compared to pure ZnO thin films. This Raman peak shift shows that a tensile stress existed in the Ag-doped ZnO film.

Abstract: In this work, porous silicon (PSi) was prepared by electrochemical etching and used as a template for ZnO nanostructures. ZnO nanostructures were grown using the catalytic immersion method at different molar ratio concentrations of the precursor and stabilizer. The ZnO nanostructures were analyzed using FESEM and photoluminescence (PL) spectrometry, before tested with ethanol solution. The population of the ZnO nanostructures on PSi increased with the concentration and followed the surface morphology of PSi. The photoluminescence spectra of ZnO show two dominant peaks in the UV and visible regions. When the concentration of the precursor increased, the PL peaks in the visible region (630 nm) shifted towards the blue region of the spectrum. The PSi/ZnO nanostructure chemical sensor has a large surface area, reversing sensor and fast response in ethanol. The performance of the sensor was affected by the morphology and defect structures of the ZnO nanostructures layer.

Abstract: Different layers of PMMA spin coated onto substrate were successful prepared by sol-gel spin-coating method. PMMA was dissolved in toluene solvent and was aged for 24 hours to produce the homogeneous solution. The films were then characterized by Raman Spectroscopy and Ultraviolet-Visible (UV-Vis) spectroscopy. Raman spectroscopy studied reveals the 7 layers of PMMA film exhibit the strong and sharp intense peak at observed band around 810 cm^-1 that is due to the symmetric CC₄ stretching. The UV-Vis measurement present 7 layers of PMMA film have good absorption due to the small size of particles and uniform surface of the film.

Abstract: In this studies, we present different layers of PMMA films spin coated onto glass substrate by using sol-gel spin-coating method. Atomic Force Microscope (AFM) reveals the surface morphology of the samples uniformly distribute on the substrate. 1 layer sample show white particles of PMMA clearly spread on the substrate and become closely-packed after the layer of PMMA increase to 3, 5 and 7 layers. 7 layers completely dense surface morphology due to the excessive number of the particles of PMMA in the sample. The approximate roughness was recorded between ranges 0.10 – 0.25 nm. Raman spectra shown 7 layers of PMMA films as the lowest Raman intensity with strong and intense peak at band about 1024 cm^-1 which is probably due to the excessive number of particles and rougher surface present in the sample.

Abstract: Mist-atomization deposition method was applied in order to grow ZnO nanostructures with various surface morphologies. ZnO was deposited from the mixture of zinc nitrate hexahydrate (Zn (NO₃)₂.6H₂O) and stabilizer, hexamethylenetetramine (HMTA, C₆H₁₂N₄) aqueous solutions onto Au-seeded glass substrate. The mixture was sprayed onto the surface of Au-seeded glass substrate at various growth temperatures of room temperature (RT), 100, 200, and 300 °C. The obtained structures were characterised by room-temperature photoluminescence (PL), field emission scanning electron microscopy (FESEM), and UV-VIS-NIR spectrophotometer. It is found that ZnO growth on 300 °C substrate temperature shows the best absorbance properties and highest UV emission peak with denser distribution amongst all. The optical and morphological properties of sprayed ZnO nanostructures largely depend on the substrates temperature during spraying the zinc nitrate solution and on the Au-seeded glass substrates.

Abstract: In this study, Zinc oxide (ZnO) nanostructures have been fabricated on glass substrates coated with Titanium dioxide (TiO₂) of different layers, which act as seeded-template, by a solution-immersion method. The substrates were coated with TiO₂ by using sol-gel spin coating at five different layers of TiO₂: 1, 3, 5, 7 and 9. The effects of the layers to the growth of ZnO nanostructures were observed by using Ultraviolet-Visible (UV-Vis) spectroscopy, Raman spectroscopy and Photoluminescence (PL) spectroscopy. UV-vis spectra of films display the increasing of absorbance properties at visible region as the TiO₂ layers increase, as well as at UV region. Meanwhile, at visible region the transparency of TiO₂: ZnO films reduce as the layers of TiO₂ increase from 1 layer to 9 layers. Raman analysis shows the presence of ZnO in all the TiO₂ seeded-templates. From the result, it is confirmed the existence of mixed crystalline structure of both materials in these TiO₂: ZnO thin films and PL spectra of the films show seeded TiO₂ thin films has lower intensity of visible emission and high ratio of I_UV/I_VIS compared to the non-seeded TiO₂ This contributes to the lower structural defects, oxygen vacancies, impurities and has the most improved optical properties.

Abstract: ZnO nanostructures were obtained by mist-atomisation technique. Nanostructured ZnO can be grown in aqueous solution of zinc nitrate hexahydrate as precursor solution with the addition of stabilizer hexamethylenetetramine (HMTA). ZnO nanostructures deposited by mist-atomisation, with applied heat from the glass substrates’ downside. Firstly, the glass substrates were seeded by Au with different thickness of 0 (non-seeded), 6, and 12 nanometer (nm). The growth of ZnO on different Au-seeded thickness is studied. The optical properties of ZnO nanostructures were examined by Ultraviolet-Visible (UV-Vis) spectroscopy. The morphology of the ZnO thin films obtained was studied by FESEM. FESEM micrographs shows different nanostructures formed on different thickness of Au-seeded glass. UV-vis spectra of ZnO nanostructures display high absorption in the UV region and high transparency in the visible region. There is improvement in UV absorption for ZnO growth on 6nm Au-seeded compared to non-seeded and 12 nm Au-seeded glass due to imperfect alignment of ZnO nanostructures.

Abstract: Tin-doped Zinc Oxide (Sn-doped ZnO) thin films were prepared using zinc acetate dehydrate as a starting material by sol-gel immersion method. The doping concentrations were varied at 0 at.%, 1.0 at.%, 2.0 at.% and 3.0 at.%. The synthesized samples were characterized by Field Emission Scanning Electron Microscopy (FESEM).

Abstract: Sol gel immersion method has been used to synthesize magnesium doped zinc oxide (Mg:ZnO) thin film on glass substrate. The morphological of annealed thin film was study using atomic force microscopy (AFM) while UV-Visible spectroscopy was used to examine the optical transmittance properties. The optical band gap was estimated by using Tauc’s method. From the results, the surface roughness was change as annealing temperature increases. The increasing of annealing temperature also affects the transmittance spectra which are shifted to lower wavelength. The optical band gaps of the thin film were varied due to different annealed temperature.

Abstract: Titanium Dioxide film will be deposited on a glass slide substrate by spin coating technique which is the frequently used technique because of its easy operation and cheap due to the sol gel preparation. The deposited films were then characterized by cross section technique using Field Emission Scanning Electron Microscopy (FESEM) to investigate the thickness based on the number of coatings. Then by the same FESEM, the surface morphology was studied to see the grain size and the porosity of each film based on the number of coatings. AFM was used to see the uniformity of the thin film's surface. Then by using current voltage (IV) measurement, the electrical property of the film can be studied, from IV characterization the resistivity of the film will be calculated. In this investigation, it is found that by increasing the coating layer, the resistivity values were decreasing whereas the conductivity of the film is increasing since conductivity is the inverse of resistivity. The porosity of the film also increases with the coating layers.