Papers by Author: Zuraida Khusaimi

Abstract: Tin oxide (SnO₂) nanostructured thin film with different immersion times was prepared on zinc oxide (ZnO) seeded catalyst using immersion method. The immersion times were varied at 3.0, 3.5 and 4.0 hours. Field emission scanning electron microscopy (FESEM) and two point probes current-voltage (I-V) measurements were used to study the surface morphology and electrical properties of SnO₂ nanostructured thin films. The diameter size of SnO₂ nanostructures which immersed at 3.0, 3.5 and 4.0 h were in range 10-20 nm, 20-30 nm and 30-50 nm, respectively. The results shows the highest electrical properties was at 3.0 h of immersion time.

Abstract: In this work, seeded porous silicon (PSi) was used as a substrate in the growth of ZnO nanostructures. PSi was prepared by electrochemical etching method. ZnO thin films as seeded were deposited via sol-gel spin coating method. ZnO nanostructures were grown on seeded PSi using hydrothermal immersion method. In order to study the effect of post-heat treatment on the substrate, post annealing temperature were varied in the range of 300 to 700 °C. The FESEM results shows ZnO thin film composed of nanoparticles were distributed over the PSi surface. Based on AFM characterization, the smoothest surface was produced at post annealing temperature of 500 °C. There are two different peaks appeared in PL characterization. The peak in near-UV range is belonging to ZnO thin films while a broad peak in visible range can be attributed to ZnO defects and PSi surface. In addition, FESEM, XRD and PL were used to characterize the ZnO nanostructures. The FESEM results revealed ZnO nano-flower were successfully grown on seeded PSi. Hexagonal wurtzite of ZnO with dominated by the plane (100), (002), and (101) was found by XRD characterization. Two different peaks in UV range and visible range can be attributed to ZnO nano-flower and various defects of ZnO, respectively.

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: In this study, ZnO nanostructures were synthesized on porous silicon (PSi) substrate using hydrothermal immersion method. Different post-annealing temperatures were varied from 300°C to 600°C. Surface morphology was studied by field emission scanning electron microscopy. It shows that a better shape was produce at annealing temperatures of 500°C. Structural studies of ZnO nanostructure were implemented using X-ray diffraction grating. The result shows post-annealing can influence the crystallinty of ZnO. Photoluminescence spectra were used to study the optical properties of ZnO nanostructure. The result shows that peak corresponds to ZnO nanostructures are appeared in UV range. Besides, broad peaks are also appeared in visible range which is attributed to structural defects and PSi substrate.

Abstract: In this research, we prepared aluminium (Al)-doped ZnO nanorod arrays on the glass substrate using sonicated sol-gel method. These nanorod arrays were annealed at 500 °C in air and oxygen environment using thermal furnace. Field emission scanning electron microscopy (FESEM) image reveals that nanorod arrays were deposited vertically aligned on the substrate. The stress characteristics of air-annealed and oxygen-annealed Al-doped ZnO nanorod arrays were investigated using Raman spectroscopy and X-ray diffraction (XRD) measurement. The electrical properties of the samples were investigated using two-probe current-voltage (I-V) measurement system. The results show that annealing atmospheres greatly influenced the stress and electrical properties of the nanorod arrays.

Abstract: In this research, we fabricated UV photoconductive sensor using aluminium (Al)-doped ZnO nanorod-nanoflake network thin film. These nanostructures were deposited on the seed-layer-coated glass substrate using sonicated sol-gel immersion method. By using Al contacts, it was found that the performance of the UV photoconductive sensor is very good. The responsivity of the device was 46.4 mA/W with sensitivity of 17.5 under 365-nm UV light (5 mW/cm²) at bias voltage of 10 V. Our study revealed that these nanostructures are very promising material for the UV photoconductive sensor applications.

Abstract: Titanium dioxide nanowires have successfully prepared by hydrothermal method. The effect of hydrothermal growth temperature on the morphology and structural properties of TiO2 nanowires have been investigated. It was observed that at low temperature of 100 °C, the formation of nanowires was at early stage, while hydrothermal treatment at 130 °C showed the TiO2 precursor acquired enough energy for formation of the nanowires. Increased the temperature to 200 °C was formed the bundle of nanowires in microsize. The diameter of nanowires increased as the temperature increased. The TiO2 nanowires produced at temperature of 150 °C and annealed at 500 °C showed highest crystallinity with anatase phase.

Abstract: ZnO nanorods were successfully grown on Au coated Si substrate and Si bare substrate. The growth was using sol-gel immersion method at different deposition time which is 2, 4, 6, 8, 10 and 12 hours. In the presence of Au, growth rate of nanorods is much faster as it performs as a catalyst by decreasing the growth time of ZnO nanorods to half compared to growth on Si substrate without Au coated. Using Scanning Electron Microscope (SEM), changes in growth of nanorods at different deposition time was captured and the structural properties are discussed.

Abstract: This paper presents a review on synthesis, structure, and growth mechanisms of one-dimensional nanostructures of ZnO. Solution-based method is a potential deposition technique for large-scale production as its advantages; the low cost, the simplicity of experimental set-up, and the low operating temperature. Mist-atomiser technique is one of the solution-based methods in synthesizing optimized ZnO nanostructures. Doping will lead for better properties of ZnO, which result to wide application area. Nanostructured ZnO is important in promising areas of application which devices utilizing nanostructures such as gas sensors and solar cells, since it is fairly easy to fabricate such forms of ZnO nanostructures, which have good charge carrier transport properties and high crystalline quality.

Abstract: Low-temperature solution immersion growth of low-dimensional ZnO nanostructures on gold-seeded Si substrate has been demonstrated. pH environment of the precursor solution, Zn(NO3)2.6H2O (zinc nitrate hexahydrate) and C6H12N4 (HMTA) was found to have considerable effect to ZnO morphology and photoluminescence. Structural, morphological and photoluminescence (PL) properties of the samples were obtained from XRD, SEM and PL-Raman characterisation. A near neutral (pH = 6.8) and acidic (pH = 5) precursor solution aided a dense near-aligned ZnO nanorods growth with smallest rods diameter of 30 and 20 nm respectively. Whereas alkaline precursor solution (pH = 9) gave rise to flower-like structures of ZnO. Chemical equations for the reactions and the role of H+ and OH- ions role in affecting the XRD diffraction peaks and morphology, are suggested. Room temperature PL emission spectra of ZnO were collected after excitation at 325 nm. UV and visible emission distinctive of ZnO were formed and the rationale for significant shifts of the visible emission was also discussed.