Azlinda Ab Aziz

Surface Morphology of Seeded Nanostructured ZnO on Silicon by Sol-Gel Technique

Nanostructured ZnO as a seeded was prepared by sol-gel technique on p-type silicon in various low molarities. Zinc acetate, Diethanolamine (DEA), and isopropyl were use as starting material, stabilizer, and solvent respectively. Atomic Force Microscopy (AFM) analysis shows smooth surface and uniform layer were produced in low molarities of precursor. The surface morphology of nanostructured ZnO was analyzed by Field Emission Scanning Electron Microscopic (FESEM). It is found that the nanostructured ZnO were successfully deposited on the silicon substrate with size ~10 nm to ~35 nm. Photoluminescence spectroscopy was employed to study the band gap in room temperature. It shows that very low intensity of PL in 0.05m and 0.1 m. PL intensity become more obvious starting from 0.15 m of precursor concentration.

Seeded Porous Silicon Preparation as a Substrate in the Growth of ZnO Nanostructures

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.

Photoluminescence Spectra of ZnO Thin Film Composed Nanoparticles on Silicon and Porous Silicon

ZnO thin film was successfully deposited on different substrate by sol-gel spin coating. Zinc acetate dihydrates, diethanolamine and isopropyl were used as starting material, stabilizer and solvent respectively. Two different substrate used in this work are p-type silicon wafer and porous silicon. Porous silicon was prepared by electrochemical etching. In order to study the surface morphology, field emission scanning electron microscopy (FESEM) was employed. It is found that, ZnO thin film was composed by ZnO nanoparticles. The averages size ZnO nanoparticle is 23.5 nm on silicon and 17.76 nm on porous silicon. Based on Atomic Force Microscopy (AFM) topology analysis, surface of ZnO thin films on porous silicon was rougher compared to ZnO thin films on silicon due to substrate surface effect. Photoluminescence spectra shows two peaks are appear for ZnO thin film on silicon and three peaks are appear for ZnO thin film on porous silicon. PL spectra peaks of ZnO thin film on silicon are correspond to ZnO and ZnO native defects while peaks of PL spectra on porous silicon are corresponds to ZnO, ZnO native defects and porous silicon.

Annealing Effect on the Surface Morphology and Photoluminescence Properties of ZnO Nanorod Prepared by Catalytic-Immersion Method Grown on Si and Au/Si substrate

ZnO nanorods were prepared by immersion method deposited onto Silicon (Si) and gold-seeded Si (Au/Si) substrate. The annealing temperatures were varied from 400, 500 and 600 °C. The effect of annealing temperature on the surface morphology and photoluminescence characteristics was investigated. The samples were characterized by Field Emission Scanning Electron Microscope (FESEM) to study their morphology and structural properties while the optical properties were characterized at room temperature using Photoluminescence Spectroscope. The shape of ZnO showed growth of nanorods with hexagonal shape. As the annealing temperature increased, the morphology study indicates that particle size of ZnO decreased while the crystallinity increases. The structures has high surface area, is a potential metal oxide nanostructures to be develop for optoelectronic devices and chemical sensors.

Effect of Post Annealing Temperature on Surface Morphology and Photoluminescence Properties of ZnO Thin Film

Zinc acetate as starting material along with diethanolamine as a stabilizer and isopropyl as a solvent were used in ZnO precursor preparation while p-type silicon was used as a substrate in this work. ZnO thin films were deposited on silicon wafer by spin coating deposition method. Samples were annealed at different temperature in range 500°C to 800°C. In other to study the surface morphology of thin film, Field Emission Scanning Microscopic (FESEM) was employed for every sample. It was found that, the thin films are composed by ZnO nanoparticles with size of about 18.3 nm to 32.95 nm. Topology of ZnO thin films was characterized by atomic force microscopy (AFM). In other to study the photoluminescence properties, 325 nm of xenon lamp was used as sources within range of 350 nm and 600 nm. It is found that two peaks are appears for the entire sample with the high intensity peak at 373 nm originated from the contribution of near band edge recombination from ZnO and low intensity at 573 nm was corresponding to ZnO defects.

Effect of Precursor Concentration in the Synthesization of ZnO Nanostructures by Solution-Immersion Method

The effect of precursor concentration ranging from 0.1 to 0.5 M using the mixture of zinc nitrate hexahydrate (Zn(NO3)2.6H2O) and urea (CH4N2O) at 60 oC evaluated in this study. ZnO nanostructures have been prepared by solution immersion method on gold-seeded silicon substrate (Si/Au). Solution immersion method was adopted with the intention to develop a large area deposition at low-temperature benign method of preparation. As concentration increase, the morphologies are seemingly changed from rod (~300 nm) to accumulated nanosheets that consist of many pores. The structural and optical effect of changing the precursor concentration on the synthesization of ZnO films were investigated by X-ray diffractometer (XRD) and room temperature photoluminescence (PL) measurement, respectively. A unique development of size and growth orientation is seemingly affected by the change of the precursor concentration.

Growth of ZnO Nanosturctures on Porous Silicon in Different Concentration of Zn2+ Ion

In this work, zinc nitrate was used as starting materials while hexamethylenetetramine as stabilizier and deionized water as a solvent. Electrochemical etching method was employed to modify p-type silicon wafer surface in substrate preparation. ZnO nanostructures were simply deposited on substrate by sol-gel immersion method. Different molarities of precursor were prepared to study the effect of Zn2+ ion concentration in growth of ZnO nanostructures. Field Emission Scanning Electron Microscopic (FESEM) revealed that concentration of Zn2+ ion precursor influences the growth of ZnO nanostructures. ZnO nanoflower was formed in low molarity and becomes nanospherical composed by nanorods in high molarity. X-Ray diffraction (XRD) spectroscopy was employed to analyse the structural properties. The result was confirming the formation of hexagonal wurtzite of ZnO nanostructures. Besides, the growth of ZnO nanostructures was aligned to (002) towards higher molarity.

Effect of Urea as a Stabiliser in the Thermal Immersion Method to Synthesise Zinc Oxide Nanostructures on Porous Silicon Nanostructures

In this work, ZnO nanostructures were prepared using the catalytic immersion method (90 °C) with zinc nitrate hexahydrate (Zn (NO3)26H2O) as a precursor, urea (CH4N2O) as a stabiliser and porous silicon nanostructures (PSi) as a substrate. PSi prepared on p-type Si by using electrochemical etching method. Different molarity concentration ratios of Zn (NO3)26H2O to CH4N2O (2:1, 1:2, 1:4 and 1:6) were used in this work. The effects of the urea concentration during the synthesis process were discussed. The ZnO nanostructures were characterised using field emission scanning electron microscope (FESEM), photoluminescence (PL) and I-V probe. Porous nanoflakes were successfully synthesised on a p-type PSi substrate that was prepared by electrochemical etching. High-intensity photoluminescence (PL) at the optimum concentration indicated that urea is a good stabiliser to produce ZnO nanostructures with good crystallinity. The high resistance of ZnO/PSi show that electrical properties of PSi dominant compare to ZnO nanostructures.

Effect of Al2O3 on the electrical conductivity and structural study in MgI2-Mg3(PO4)2 based solid electrolyte

The effect of filler to the binary compound of Magnesium Iodide ( MgI2) and Magnesium Phosphate (Mg3 (PO4)2 is investigated. A small amount Alumina (Al2O3) filler in the range of 2-10 weight percent is added to the optimum composition with maximum conductivity of binary compound 0.7 Mg3(PO4)2 and 0.3 MgI2.The electrical conductivity of theMgI2- Mg3 (PO4)2 - Al2O3measured using the impedance spectroscopy (IS) method and result shows that the electrical conductivity of the compound has improved up to 9.84x10-4Scm-1. Field Emission Scanning Electron Microscopy (FESEM) images show some changes in the morphology after introduce the filler. The samples with filler showsnano flakes like structure with some space createdallowing the Mg2+cations to migrate that lead to enhanced conductivity.