Papers by Keyword: Thin Film

Abstract: Zinc Oxide (ZnO) nanostructured was synthesized by green method. The zinc acetate dehydrated, Zn (CH3COO)2.2H2O was mixing with psidium guajava leaves extract as reducing as well as capping agent which is very simple, rapid, cost-effective and environment friendly route. However, Titanium Dioxide (TiO₂) sol-gel was synthesized by using titanium (IV) butoxide, Ti (OC4H9)4, butanol, C₄H₉OH, acetic acid, CH₃COOH, and distilled water, H₂O. The deposition of ZnO/TiO₂ thin films on the glass substrate applied by spin coating method. The calcination temperature has been used for the first layer of ZnO were 400 °C, 500 °C, 600 °C and for the second layers, which is TiO₂, were 500 °C and 600 °C. Four types of characterization were perform to analyse the ZnO/TiO₂ thin films such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and Atomic Force Microscopy (AFM). From XRD analysis, the result shows the zincite structure of ZnO thin films and the anatase structure of TiO₂ thin films. Besides, increasing the calcination temperature will increase the peak intensity. Furthermore, FESEM performed to analyse the surface morphology of ZnO/TiO₂ thin films, which is when calcination temperature increase will increase the size of the particles. Meanwhile, the analyzing of ZnO/TiO₂ thin film using AFM shows that with increasing the calcination temperature will increase the surface roughness and particle size. The UV-Vis was use to determine the optical properties of the ZnO/TiO₂ thin films where it shows the percentage transmittance improved after increase calcination temperature.

Abstract: We report on a development of the structural, optical and electrical properties of poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS) conducting polymer thin films. The PEDOT:PSS thin films were deposited by a controlled thin film applicator and their physical properties were found to be effectively modified by isopropanol. The deposited films were investigated by several techniques including XRD, UV–Vis, SPM and Hall-effect. Interestingly, by optimizing the PEDOTS:PSS/ISO volume ratio (v:v), we find that the film charge carriers type can be switched from p to n-type with a high bulk carriers concentration reaching 6×10¹⁷ cm^-3. Moreover, the film surface roughness becomes smoother and reaching a small value of only 1.9 nm. Such development of the PEDOT:PSS film properties makes it very promising to act as an electron transport layer for different energy applications.

Abstract: Heterostructure thin films of indium and zinc oxides (IZO) were prepared by spray pyrolysis from an aqueous solution of the precursors at different substrate temperatures (T_S). The polycrystalline structure of bixbyite appeared at a low temperature. The crystallinity was enhanced with the emergence of the zinc oxide phase. By increasing the T_S to 623 K, the crystallite size was increased. SEM images reveal that the deposited sample at 523 K is composed of irregularly shaped nanoparticles with a lack of links. Increasing the T_S to 573 K increases the average particle diameters, and the particles appeared as polyhedrons well connected with cavities between them, which candidates for gas sensing applications. Increasing T_S to 623 K resulted in the particles merging. NO₂ gas sensor results confirmed the enhancement of IZO sensitivity performance at 573 K. Keywords: Gas sensor, thin film metal oxide, spray pyrolysis, In₂O₃– ZnO

Abstract: Complex metal hydrides are one of the most effective hydrogen storage materials due to their unique property to absorb and desorb hydrogen with the hydrogen storage capacity of about 5-7 wt%. In this study, lithium aluminium hydride (LiAlH₄) was coated on glass substrate using dip coating method. The coating conditions investigated were LiAlH₄ concentrations of 6 g/l, 10 g/l and 20 g/l and post-annealing time from 0 to 60 min. Phase and grain size of the deposited LiAlH₄ were analyzed using X-ray powder diffraction (XRD). Scanning electron microscope (SEM) was used for surface morphology analysis. The hydrogen storage capacity of the deposited thin films was analyzed using thermogravimetric analysis (TGA). The experimental results revealed that the phase of the deposited LiAlH₄ thin films on glass substrate were mixed with lithium aluminium hydroxide hydrate (LiAl₂(OH)₇·2H₂O) and lithium hexahydroaluminate (Li₃AlH₆). The intensity of the LiAl₂(OH)₇·2H₂O and LiAlH₄ peaks tends to decrease with increasing LiAlH₄ concentration and post-annealing time while the intensity of the Li₃AlH₆ peaks increased with increasing LiAlH₄ concentration and post-annealing time. The grain size was decreased with increasing LiAlH₄ concentration and post-annealing time. The smaller grain size the better the hydrogen storage capacity. The hydrogen storage capacity of the deposited LiAlH₄ thin film was increased from 0.124 wt % using LiAlH₄ concentration of 6 g/l without post-annealing to 1.675 wt % using LiAlH₄ concentration of 20 g/l with 60 min post-annealing time.

Abstract: Na_0.5K_0.5NbO₃ (KNN) thin films were fabricated on (100) oriented SrTiO₃ substrates by spin coating a stable environmentally friendly aqueous KNN precursor. Homogeneous films with an average grain size down to 60 nm were observed after heat treatment at 900 °C. The high degree of texture was confirmed by XRD. The intensity of the KNN (100) reflection for films on (100) oriented substrates increased with increasing sintering temperature up to 900 °C. The ferroelastic and piezoelectric properties of the film was confirmed by PFM. Local piezoelectric properties of selected films will be discussed in relation to the processing conditions, microstructure and orientation of the substrate.

Abstract: Aloe Vera and sea cucumber are the natural material which has been used widely in bio-medical field in Malaysia, especially for wound healing purposes due to its therapeutic effects. Recently, thin films which can absorb acceptable amount of fluid has been gaining attentions in biomaterial wound dressing applications. Hence, the incorporation of these natural materials in the fabrication of the thin films were investigated regarding the fluid intake capacity under the condition of being in contact with deionized water and pseudo-wound exudate. Three types of films made of different compositions of Aloe Vera and sea cucumber were prepared and evaluated. The morphology of the films was analysed using the Scanning Electron Microscopy (SEM) evaluation and the fluid intake capacity through the Free Swell Absorptive Capacity test. Results showed the variety of fluid intake capacity of different type of the film after being immersed in both solutions. The morphological structure of each film also varied from one another. The result also indicated that the Aloe Vera film held the adequate fluid intake capacity without any degradation behaviour.

Abstract: Thermo-responsive random copolymer poly (2-(2-methoxyethoxy) ethoxyethyl methacrylate-co-poly (ethylene glycol) methyl ether methacrylate), abbreviated as P(MEO₂MA-co-OEGMA₃₀₀) was synthesized by 2-(2-methoxyethoxy) ethoxyethyl methacrylate (MEO₂MA) and poly (ethylene glycol) methyl ether methacrylate (OEGMA₃₀₀) with a molar ratio of 1:1 via atom transfer radical polymerization (ATRP). The structure of P(MEO₂MA-co-OEGMA₃₀₀) was confirmed by ¹H NMR and GPC. The transition behaviors of P(MEO₂MA-co-OEGMA₃₀₀) in aqueous solution were investigated by UV-Vis and DLS. While the transition behaviors of P(MEO₂MA-co-OEGMA₃₀₀) thin films were probed by white light interferometry. Compared to the P(MEO₂MA-co-OEGMA₃₀₀) in solution, it shows a much broader transition region, which is a promising candidate for the slow release of drug in the field of medicine.

Abstract: The surface wettability of thermo-responsive random poly (ethylene glycol methyl ether methacrylate-co-triethylene glycol methyl ether methacrylate), abbreviated as P(MEOMA-co-MEO₃MA), was investigated in thin film. UV-Vis spectroscopy shows that the LCST of P(MEOMA-co-MEO₃MA) with molar ratios of 0:20, 6:14 and 9:11 were 43°C, 32 ^oC and 25 ^oC, respectively. LCST shifts towards lower temperature when molar ratio of MEOMA increases. ATR-FTIR indicates that P(MEOMA-co-MEO₃MA) thin film experienced a collapse when the temperature passes its LCST. The contact angle of the paraffin oil on the film decreases 15^o when the temperature is above its LCST, which confirms the surface wettability can be controlled. Atomic force microscopy shows the surface of the swollen thin film becomes rougher when above it LCST.

Abstract: β-AgI thin films with thicknesses of 0.09–8.9 µm were prepared on polyethylene terephthalate (PET) substrate. Dependence of ionic conductivity on the thickness of the β-AgI thin film was measured via impedance spectroscopy in the temperature range of 300–330 K. It has been confirmed that the ionic conductivity of the b-AgI thin film is several hundred times higher than the b-AgI bulk. The enhancement of ionic conductivity is considered to be due to the formation of a high ion-conducting region near the hetero-interface region of b-AgI and PET. Furthermore, it has been suggested that the activation energy and carrier density may change depending on the distance from the interface, and the thickness dependence of enhancement in ionic conductivity may be related to the film thickness dependence of crystal orientation and structural disorder of β-AgI thin films.

Abstract: Zinc oxide (ZnO) has attracted considerable attention because of its potential applications in optoelectronic devices. Many scientists have reported on the preparation of ZnO based photodetectors in metal-semiconductor-metal (MSM) structures where expensive noble metals are used as electrodes. Here, we propose the preparation of full metal-oxide photoconductors by using indium tin oxide (ITO) as the electrodes and ZnO thin films as sensing materials. ZnO thin films were prepared by employing a simple ultrasonic spray pyrolysis (USP) technique with a commercial ultrasonic nebulizer (1.7 MHz). In this work, we developed a high performance ZnO based photodetector on interdigitated ITO with a simple and low-cost USP method. The I-V characteristic shows that ZnO thin film works in a photoconductive mode and has better performance as a UV (325 nm) detector than other wavelengths (505, 625 and 810 nm). As a UV detector, the devices exhibit high sensitivity (1255.51%), high responsivity (22.6 x 10³ A/W), high detectivity (1.49 x 10¹⁴ Jones), good stability, a fast response time of 0.87 s and a relatively slow recovery time of 34.8 s. This high performance may be related to the large crystallite size that facilitates higher electron mobility.