Abstract: Nickel (Ni)-doped zinc oxide (ZnO) layers were deposited simultaneously by radio frequency (RF) magnetron sputtering from a Ni and ZnO target. A Ni seed layer was used as catalyst prior to the deposition of Ni-doped ZnO. The Ni seed layer was grown with 15 sccm of Ar flow rate while the Ni-doped ZnO was grown with mixture of Ar:O2 at 25:5 sccm gas flow rate ratio. The deposition pressure is 5 mTorr for both Ni seed layer and Ni-doped ZnO layer. This paper studies the influence of deposition temperature to the Ni seed layer and Ni-doped ZnO layer at temperature range from room temperature (RT) until 500°C with an increment of every 100°C. The sample was characterized using field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD) and UV visible spectroscopy (UV-vis) to determine the structural, crystallinity and optical properties of the deposited layer. FESEM surface analysis shows that uniformity of the nanocolumns is improved when deposition temperature is increased. The transmittance of the deposited nanocolumns was improved when temperatures are increased to 500°C.
Abstract: Calixarenes are promising compounds to be used as ionophores and for molecular recognition. Their ability to form Langmuir and Langmuir-Blodgett (LB) films is of great interest in order to obtain small sensor devices which incorporate an active nanometric film. Calixarene (Calix4) has been used in this work and its ability to form Langmuir films has been shown. Calix4 forms monolayers but at higher compressions tends to form multilayers. The presence of ions in the subphase, as lead chloride salt solutions, leads to some changes in the surface pressure-area (П-A) isotherms and surface potential-area (ΔV-A) isotherms. The effective dipole moments (μ) of the calixarene molecules in the uncomplexed and complexed states has been calculated from the ΔV values by using Helmholtz equation. Some characteristics of the films and mean molecular area have been deduced from the isotherms graph.
Abstract: Indium tin oxide (ITO) nanocolumns were successfully deposited on both glass and silicon substrates at different substrate temperature from room temperature to 300°C by radio frequency (RF) magnetron sputtering system using an ITO target. The composition of the ITO target was 90% indium oxide and 10% tin oxide. Structures and morphological properties of ITO nanocolumns were investigated. X-ray diffraction (XRD) measurement revealed that the main preferred orientation was changed from (222) to (400) as the substrate temperature increased. The atomic force microscopy (AFM) reveals that the roughness values were increases as the substrate temperature increases. The cross sectional and top view field emission scanning electron microscopy (FESEM) images show that densely packed nanocolumn arrays were obtained from all the samples.
Abstract: Pb (ZrxTi1-x)O3 films at morphotropic phase boundary composition (x=0.52) were deposited on Pt/Ti/SiO2/Si substrates by sol-gel spin on technique. Thickness of the films were varied up to 1μm by step-by-step crystallization process and annealed at 500, 600 and 700 °C. Films annealed at 500 °C had poor degree of crystallization for all the thicknesses while 600 and 700 °C annealed films were found to be well crystallized with a (111) preferential orientation. Also an enhanced degree of preferential orientation was observed on the films annealed at 600 °C compared to films annealed at 700 °C. Room temperature dielectric measurements showed higher dielectric constant values for the films annealed at 600 °C compared to films annealed at 700 °C. The remnant polarization (Pr) and coercive field (Ec) at an applied field of 160 kV/cm depicted that 600 °C annealed films had a higher Pr and lower Ec values compared with the 700 °C annealed films attributed to the higher degree of preferential orientation.
Abstract: Porous alumina films are widely used as templates for fabricating one-dimensional (1-D) nanostructures such as nanowires or nanotubes. Using a two-step anodisation process, we have successfully optimized the growth conditions for fabricating highly ordered porous alumina films with pore diameters ranging from 20 to 150 nm, to be used as templates for 1-D nanostructure synthesis. The effects of the anodisation conditions on pore structure and the formation rate of the films were systematically studied. It was found that low electrolyte temperatures and agitations decreased the growth rate of the films but favored the process of pore ordering. Removal of oxide layer formed from first anodisation process and removal of barrier oxide at pore ends had an important bearing on pore morphology. Besides the stand-alone porous alumina films, we have also fabricated porous alumina films on rod-shaped Al substrates.
Abstract: Aluminium Oxide (Al2O3) thin films have been widely used in many kinds of applications due to their excellent properties such as good mechanical strength, high abrasive and insulating characteristics. In this work, Al2O3 thin films are deposited on silicon (100) substrates using pulsed laser deposition (PLD). The deposition is done using different chamber environments. The crystal structure of the thin films is investigated using Grazing Incidence Diffraction (GID). The surface morphology and thicknesses of the thin films are studied by Field Emission Scanning Electron Microscopy (FESEM). The electrical current-voltage (I-V) characteristics of the thin films are measured using Signaton H150 Probe Station with Keithly 302 source measurement. It was found that the different process parameters greatly influenced the characteristics of the thin films obtained. FESEM images show high quality, smooth and dense films obtained using the PLD method. Generally, all films show rectifying behaviour.
Abstract: In this work, cuprous oxide (Cu2O) thin films grown on glass and polyethylene terephthalate (PET) substrates using reactive radio frequency magnetron sputtering system were investigated. Copper target with purity of 99.99% were used while high purity argon-oxygen gases were utilized as sputtering gases. Structural, morphological, and optical properties of the films were investigated by X-ray diffraction (XRD), atomic force microscopy and ultra-violet visible spectrophotometer. From the XRD results, only one single diffraction peak corresponding to cubic Cu2O (111) crystal structure were observed for both substrates. The surface morphologies of the samples were in a form of pillar-like. Root mean square surface roughness for Cu2O on glass and PET substrates were 3.37 nm and 3.20 nm, respectively. The films were highly transparent for wavelength above 600 nm. The Cu2O films have direct band gap values of around 2.56 eV as determined by Taucs method.
Abstract: Thin films CuInSe2 (CIS) cells have been fabricated by the electro chemical method. Some of the physical properties such as lattice parameter, crystal structure and grain size of CuInSe2 (CIS) films with different Cu/In ratios ( 0.50-1.1) were determined using X-ray diffractornetry. The surface morphology with different Cu/In ratios was studied using a scanning electron microscope. The SEM studies on these films showed that the grain size increases the Cu/In ratios increases from 0.49 to 1.1. The variation of the band gap with different Cu/In ratio was determined from optical absorption measurements. The results showed that the band gap decreases as the Cu/In ratio increases over the considered range of composition. Key words: Thin films, Lattice Parameter , Optical Absorption, grain size
Abstract: In this work, the influences of plasma pre-treatment on polyethylene terephthalate (PET) substrate to the properties of ZnO thin film have been carried out. ZnO thin films were successfully grown on PET substrate by spin coating method. In order to study the effects of plasma pre-treatment, a comparison of treated and untreated condition was employed. Water contact angle measurement had been carried out for PET wettability study prior to ZnO thin film coating. Morphology study of ZnO thin film was performed by scanning probe microscope (SPM). Besides, optical study of the ZnO thin film was done by using UV-vis spectrophotometer. All the measured results show that plasma pre-treatment of PET substrate plays an important role in enhancing the wettability of PET and optical properties of the ZnO thin films. In conclusion, pre-treatment of PET surface is essential to produce higher quality ZnO thin film on this particular substrate in which would pave the way for the integration of future devices.