Applied Mechanics and Materials Vols. 773-774

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: Titanium oxide (TiO₂) thin films were deposited onto glass substrates by spray pyrolysis method. The thin films were deposited at three different annealing time; 1, 5 and 10 hours at 400°C. The structural and electrical properties were characterized using FESEM and I-V characteristic. Polycrystalline thin film with anatase crystal structure, as evidenced from X-ray diffraction pattern, was obtained with major reflection along (101). Electrical properties have been studied by means of electrical resistivity. The dark resistivity had been measured as a function of the film thickness, d. The resistivity of samples had been found to decrease with decreasing thickness. Thus, TiO₂ is one of the most promising candidates for relatively low cost, simple manufacture for solar cell.

Abstract: Fluorine doped tin oxide (FTO) thin films were prepared at different deposition temperatures using the spray pyrolysis deposition (SPD) technique. The deposition temperature were ranging from 250°C °C to 450°C and the precursor used was 0.5M of SnCl₄.5H₂O and 1.527M of NH₄F completely dissolved in distilled water. It was observed that the conductivity of the FTO thin film increased with increasing of deposition temperature. At 450°C, it was shown the conductivity became smaller. Surface morphologies of FTO thin films at different deposition temperature had shown that the growth of crystallite particles and its distributions were totally affected by the deposition temperature. The transmittance of FTO thin films was over 80% within the wavelength from 300 nm - 800 nm. Thus, the best deposition temperature to be used is around 350°C to 400°C for depositing the FTO film.

Abstract: —Tungsten Oxide (WO3) thin films were deposited using 99.9% pure tungsten target onto ITO substrate using RF magnetron sputtering in the range oxygen flow rates of 30-50%. The influence of the oxygen flow rate on characteristic of WO3 thin films has been investigated. The transmittance, resistivity, crystallite, roughness, and surface morphology were measured by UV-Vis, 2-point probe, X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), and Field Emission Scanning Electron Microscopy (FE-SEM) respectively. Experimental result showed that the deposition rate of WO3 thin films decreased by increasing oxygen flow rate. A poor crystalinity or more too amorphous of WO3 thin films produces by using various oxygen content. A higher optical transmittance spectrum detected at 30% oxygen content about 86% at wavelength 550nm. Keywords—Tungsten Oxide (WO3); RF sputtering, sputtering oxygen

Abstract: Titaniumdioxide (TiO₂) Thin Films Have been Fabricated and Deposited on Ftoglass Substrates by Spray Pyrolysis Deposition (SPD) Method. the TiO₂thin Films were Annealed at Four Different Temperatures for an Hour. Thetemperature was Set at 100°C, 300°C, 400°C and 500°C. Surface Morphology Andelectrical Properties of TiO₂ Thin Films were Investigated Usingfesem and 2 Point- Probe I-V Measurement, Respectively. the FESEM Result Shows Thatthe Grain Size of the Tio₂ increases when Annealed Temperatureincreases. for XRD Test Shows that the Crystallinity Improved with Theincreasing of Annealing Temperature. when the Annealing Temperature Increases,the Electrical Properties of TiO₂ Also Change. the Result Shows Thatthe Optimum Temperature for Annealing of TiO₂ Thin Film was 400°C.

Abstract: Uniform Titanium dioxide (TiO₂) thin film is essential for application in high performance solar cells. A low cost approach using TiO₂ nanopowder extracted from tin mining waste to deposit TiO₂ thin films is demonstrated in this paper. Furthermore, the influence of different solvents (ethanol, acetone, isopropanol and ethylene glycol) on the formation of uniform TiO₂ thin films in sol-gel technique is studied. The films were characterized by an atomic force microscope (AFM), ultra violet – visible spectrometer (UV-Vis) and a current-voltage (I-V) measurement system. The correlations of the structural, optical and electrical behavior to the type of solvent used were discussed in details.

Abstract: Doping transition metal or rare-earth metal ion are one of the most popular topics in semiconductors. In this work, gadolinium (Gd) doped zinc oxide thin films was prepared using spin-coating technique with different concentrations in atomic percent (at.%). The influences of rare-earth ions doped into the zinc oxide films were studies. The effects on the physical and optical properties of the films were investigated by field emission scanning electron microscope, x-ray diffraction, atomic force microscopic and ultraviolet-visible spectrophotometer. It was found that the properties of zinc oxide can be tuned by changing the concentration physical and optical of Gd.

Abstract: This work demonstrates the fabrication of Cu₂O thin film onto a fluorine-doped tin oxide (FTO) glass substrate via electrodeposition method which was conducted in a solution containing copper (II) acetate monohydrate and lactic acid. While varying the deposition time ranging up to 80 minutes, the solution was kept constant at solution temperature of 40°C, solution pH 6.5 and current density-0.3 mA/cm². The characteristics of electrodeposited Cu₂O were investigated via x-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), current-voltage (I-V) test and surface profiler. The XRD results showed the intensity peak of Cu₂O corresponded to reflection (111) increased when the deposition time increased. The topological characteristics from AFM characterization showed the increment of surface roughness decreased as the time increased from 5 to 60 minutes. However, the surface roughness decreased when the time reached 70 and 80 minutes. I-V characteristics of all electrodeposited Cu₂O showed Ohmic behaviours indicating the successful fabrication of n-Cu₂O thin film. From this study, the significant effect of deposition time of Cu₂O was clearly observed and plays an important role in providing mechanism growth of the film.

Abstract: Fluorine doped tin oxide (FTO) thin film was prepared by using two different precursor solutions which are tin (ii) chloride dihydrate and tin (iv) chloride pentahydrate. These two precursors are used in spray pyrolysis process to prepare the fluorine doped tin oxide thin film. Surface Morphology of the thin film was characterized using field emission scanning electron microscope (FE-SEM). FESEM image shows the particle distribution and the morphology of fluorine doped tin oxide thin film. Two point probe I-V measurement and UV-Vis spectroscopy were used to study the electrical and optical properties of both films. Both precursors produced different particles distribution, electrical properties and also optical properties. The results show that the sheet resistance (Rs) of fluorine doped SnO₂ is about 49.24×10⁶Ω for tin (iv) chloride pentahydrate compared to 43.03×10¹²Ω for tin (ii) chloride dihydrate

Abstract: In recent years there has been renewed interest in zinc oxide semiconductor, mainly triggered by its prospects in optoelectronic applications. Doping ZnO with various elements has been a popular technique to gain the extrinsic properties for device applications. In this work we have studied the effect of Gadolinium (Gd) concentration on properties of sol–gel derived Gd doped ZnO films. The Gd concentration varying from 1 to 8 atomic percent (at.%). The structural, morphological and optical analyses were monitored by (XRD, Bruker D8 Advance), atomic force microscope (AFM, Tenko XE-100) and ultra violet-visible spectrophotometer (UV-Vis, Shimadzu UV 1800), respectively. Observations from the XRD results showed that all films exhibit the hexagonal wurtzite crystal structure and higher peak intensity observed at (002) peak. Based on XRD analysis, we also found that Gd concentration has a significant effect on the crystallite size and strain of the films. Moreover, the AFM analysis revealed that the surface become more uniform and denser as the Gd concentration increased. In addition, the optical transmittance spectra indicate that all films were highly transparent (>90%) in the visible range which slightly improved with increasing Gd concentration. The detail explanation on the mechanism will be discussed in detail in this paper.