M.F. Malek

Effect of thermal implying during ageing process of nanorods growth on the properties of zinc oxide nanorod arrays

Undoped and Sn-doped Zinc oxide (ZnO) nanostructures have been fabricated using a simple sol-gel immersion method at 95°C of growth temperature. Thermal sourced by hot plate stirrer was supplied to the solution during ageing process of nanorods growth. The results showed significant decrement in the quality of layer produced after the immersion process where the conductivity and porosity of the samples reduced significantly due to the thermal appliance. The structural properties of the samples have been characterized using field emission scanning electron microscopy (FESEM) electrical properties has been characterized using current voltage (I-V) measurement.

A study on different morphological structures of zinc oxide nanostructures for humidity sensing application

Effects of different morphological structures of ZnO to the performance of the device in the humidity sensing have been studied. Two different kinds of nanostructures were obtained which are nanords and nanoflakes. From the surface morphology image, the ZnO nanoflakes has lower diameter size of 100 nm compared to ZnO nanorods of 250 nm. The ZnO nanoflakes are not aligned and has low porous structure compared to ZnO nanorods. The humidity sensor performance of ZnO nanorods has superior performance compared to ZnO nanoflakes. The sensitivity of the ZnO nanorods sensor is 3.20 which are almost two times higher than the ZnO nanoflakes of 1.65. The structural properties of the samples have been characterized using field emission scanning electron microscopy (FESEM) electrical properties has been characterized using current voltage (I-V) measurement.

Thickness-controlled synthesis of vertically aligned c-axis oriented ZnO nanorod arrays: Effect of growth time via novel dual sonication sol–gel process

Zinc-oxide (ZnO) nanorod arrays were successfully prepared by using dual sonication sol–gel process. Field emission scanning electron microscopy revealed that the nanorods exhibited a hexagonal structure with a flat-end facet. The nanorods displayed similar surface morphologies and grew uniformly on the seed layer substrate, with the average diameter slightly increasing to the range of 65 to 80 nm after being immersed for varying growth times. Interestingly, thickness measurements indicated that the thicknesses of the samples increased as the growth time was extended. In addition, the X-ray diffraction spectra indicated that the prepared ZnO nanorods with a hexagonal wurtzite structure grew preferentially along the c-axis. Therefore, we can conclude that the diameter, length, and orientation of the ZnO nanorod arrays along the c-axis are controllable by adjusting the growth time, motivating us to further explore the growth mechanisms of ZnO nanorods.

Electrical properties of ZnO thin films prepared by sol-gel technique

Zinc Oxide (ZnO) thin films were deposited on a glass substrate by sol-gel process dip-coating method. Zinc acetate dehydrate Zn(O<inf>2</inf> CCH<inf>3</inf>)<inf>2</inf>(H<inf>2</inf>O)<inf>2</inf> are used as a starting material while 2-methoxyethanol (C<inf>3</inf>H<inf>8</inf>O<inf>2</inf>) and monoethanolamine (MEA) are used as a solvent and stabilizer. The molar ratio of zinc acetate dihydrate to MEA is 1∶1. The molarity of the solution and pre-heating temperature were kept constant at 0.4M and 150°C. Annealing temperature was fixed at 550°C but the withdrawal speed was varied from 1mm/s to 9mm/s. The effects of withdrawal speed on electrical and surface morphology of the ZnO thin films have been investigated. The electrical and surface morphology properties of the ZnO thin films were characterized by I–V measurement and atomic force microscopy (AFM). The electrical measurement showed that current decrease when the withdrawal speed increases. High conductivity at 5.87×10⁻⁴ S/cm and lowest resistivity about 1.7×10³ Ω/cm have been obtained for 1mm/s withdrawal speed. AFM micrographs showed average grain size of ZnO thin films increases from 120.862nm to 138.521nm with an increasing in withdrawal speed.

Structural and optical properties of N-doped ZnO nanorod arrays prepared using sol-gel immersion method

Nitrogen (N)-doped zinc oxide (ZnO) nanorod arrays were synthesized on aluminium (Al)-doped ZnO seed layer catalyst using sol-gel immersion method. The XRD analysis showed that the increment in crystallite sizes and lattice parameters while the strain/stress of the films reduced when the concentration increased. The FESEM image revealed that the nanorods exhibit hexagonal shape. The average diameters of nanorods have increased from 150 nm (undoped) to 230 nm (3 at.%). The N-doped ZnO nanorod arrays also displayed good transmittance properties at visible region.

Effects of Sn Dopant on Structural and Optical Properties of ZnO Thin Film Prepared by Sol-Gel Route

Tin doped zinc oxide (Sn:ZnO) thin films were prepared on glass substrates via sol-gel dip-coating technique starting from zinc acetate dehydrate, (CH3CO2)2Zn⋅2H2O and tin chloride, SnCl2. The consequences of various Sn doping on the behavior of the film was investigated. The atomic percentages of dopant in ZnO-based solution were [Sn4+]/[Zn2+] which is between 0% and 4%. The thin films were characterized using Field Emission Scanning Electron Microscope (FESEM) and UV-Vis-NIR spectrophotometer.

Humidity sensor-based zno/sno2 nanocomposite synthesised by sol-gel immersion method

ZnO/SnO2 nanocomposite was successfully prepared using sol-gel immersion method. The structural properties of ZnO/SnO2 nanocomposite were characterised using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction. The optical properties was analysed by photoluminescence (PL). The sensing properties were measured using two point probe current-voltage (I-V) measurement. The sensor characteristics depend on the composition and surface morphology of the thin film. The sensor with ZnO/SnO2 nanocomposite performed the high sensitivity with 69 times from ratio of R40RH% to R90RH% at 25°C. The response and recovery times of ZnO/SnO2 nanocomposite was 290 s and 15 s respectively. The ZnO/SnO2 nanocomposite found to be good repeatability and reproducibility. The humidity sensing mechanism was summarised.

Low temperature growth of rutile titanium dioxide nanorod arrays using a novel facile method for UV photosensor application

Titanium dioxide (TiO2) nanorod arrays (TNAs) were deposited on fluorine-doped tin oxide (FTO) coated glass substrate via a novel and facile method at the lowest deposition temperature of 110 °C for 3 hours, and characterized via fiel-demission scanning electron microscopy (FESEM), and ultraviolet-visible (UV-Vis) spectrophotometer. Self-powered UV photosensor was assembled according to photo-electrochemical cells (PEC) structure using the deposited TNAs as photoanodes. The fabricated UV photosensor was then studied for its electrical property. The fabricated UV photosensor exhibits fast response with high sensitivity under UV irradiation. A distinct ON/OFF ratio of the fabricated PEC structure also exhibits photo-sensing property as photo-anode, and can be implemented for the application of UV photosensor. The large contact area of the TNAs/electrolyte interface leads to the generation of photocurrent and exhibits improvement in conductivity.

Fabrication of Titanium dioxide nanorod arrays-based UV photosensor from low-concentration of Titanium (IV) butoxide with hydrochloric acid

A novel and facile method at lowest concentration of titanium (IV) butoxide with hydrochloric acid at 150 °C temperature for 3 hours was implemented for the growth of Titanium dioxide (TiO2) nanorod arrays (TNAs) on fluorine-doped tin oxide (FTO) glass substrate. The deposited TNAs were characterized by field-emission scanning electron microscopy (FESEM), and ultraviolet-visible (UV-Vis) spectrophotometer. Self-powered UV photosensor was designed based on photo-electrochemical cells (PEC) using the deposited TNAs as photo anodes. The performance of the fabricated UV photosensor was studied based on its photo-generated current and response under UV irradiation (365 nm). The fabricated UV photosensor displays fast response and recovery time under an ON/OFF state of UV irradiation with comparatively high sensitivity. The photosensor fabricated at the lowest 0.05 M of titanium (IV) butoxide with hydrochloric acid of TNAs exhibits photo-sensing property as photo-anodes, and can be implemented for the application of UV photosensor. Large surface area of TNAs leads to the high generation of photocurrent and shows increment in conductivity under UV irradiation.

Effect of TiO2 thickness on nanocomposited aligned ZnO nanorod/TiO2 for dye-sensitized solar cells

The TiO2 films were deposited on glass substrate at different thicknesses with different deposition frequencies (1, 2, 3 and 4 times) using spin coating technique and their structural properties were investigated. Subsequently, the nanocomposited aligned ZnO nanorods and TiO2 were formed by deposited the TiO2 on top of aligned ZnO Nanorod on ITO-coated glass at different thicknesses using the same method of TiO2 deposited on glass substrate. The nanocomposited aligned ZnO nanorod/TiO2 were coated with different thicknesses of 900µm, 1815µm, 2710µm, 3620µm and ZnO without TiO2. The dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO2 with thickness of 900µm, 1815µm, 2710µm and 3620µm and ZnO without TiO2 and their photovoltaic properties of the DSSCs were investigated. From the solar simulator measurement the solar energy conversion efficiency (η) of 2.543% under AM 1.5 was obtained for the ZnO nanorod/TiO2 photoanode-2710µm Dye-Sensitized solar cell.