Papers by Author: Mohammad Rusop

Abstract: Tin-doped Zinc Oxide (Sn-doped ZnO) thin films were prepared using zinc nitrate hexahydrate as a starting material by sol-gel immersion method. The synthesized samples were characterized by current-voltage (I-V) measurement and Field Emission Scanning Electron Microscopy (FESEM). The Sn doping concentration were varied at 1.0 at.%, 2.0 at.%, 3.0 at.% and 4.0 at.%. FESEM images show that as the Sn concentration increased, the nanoparticles size of Sn-doped ZnO become denser and less grain boundary which might help in improvement of the electrical properties.

Abstract: Performance of lead titanate, (PbTiO₃) thin films have been successfully investigated on microstructural properties, I-V characteristic, dielectric properties, and ferroelectric properties. PbTiO₃ offers variety of application as transducer, ferroelectric random access memory, transistor, high performance capacitor, sensor, and many more due to its ferroelectric behavior. Preparation of the films are often discussed in order to improve the structural properties, like existence of grain boundaries, particle uniformity, presents of microcrack films, porosities, and many more. Yet, researchers still prepare PbTiO₃ thin films at high crystallization temperature, certainly above than 600 ̊C to obtain single crystal perovskite structure that would be the reason to gain high spontaneous polarization behavior. Although this will results to high dielectric constant value, the chances that leads to high leakage current is a major failure in device performance. Thus, preparation the thin films at low annealing temperature quite an essential study which is more preferable deposited on low-cost soda lime glass. The study focuses on low annealing temperature of PbTiO₃ thin films through sol-gel spin coating method and undergo for dielectric and I-V measurements.

Abstract: The unique physical properties and strength of carbon nanotube (CNT) lend to its wide application in many fields as diverse engineering, physics and biomedicine. Biomedicine, the toxicity of CNTs was cause for concern on the application as a delivery tool for therapeutic proteins, peptides and genes in the treatment of cancer and neurodegeneration. CNTs were reported to exert adverse effects on normal neuronal function, probably due accumulation in the brain, leading to brain damage. Thus, toxicity tests of CNTs on cells would be relevant in determining potential side effects and dosage. This study was set out to evaluate the toxicity of SWCNTs derived from fermented tapioca on SH-SY5Y cells. Fermented tapioca, was a well known Malaysian local food, and was an excellent precursor for SWCNT synthesis. The raw synthesized SWCNTs were directly used to study the effect on SH-SY5Y cells. Cytotoxicity and neurotoxicity test were performed. The neurotoxicity test results showed higher cell viability compared to the cytotoxicity test. Cell viability for neurotoxicity test was above 50 % for CNT concentration ranges of 250 μg/ml and below. However cell viability decreased markedly at 500 μg/ml. The percentage of cell viability was high at 50 μg/ml and below for the first 24 h of treatment but longer treatment duration resulted in significant decrease in cell viability for all concentrations above 10 μg/ml. These findings demonstrated that CNTs were safe when used at concentration less than 10 μg/ml.

Abstract: Carbon nanotubes (CNT) has been synthesized by pyrolysing fermented tapioca liquid using an immersed heater. It was made single-walled carbon nanotubes (SWCNT) through heating at 700, 800 and 900 °C by the chemical vapour deposition (CVD) method and characterized by using Raman spectroscopy, thermogravimetric analysis and field emission scanning electron microscopy (FESEM). The synthesized SWCNT demonstrated larger diameters at 700 °C which decreased at 800 and 900 °C, respectively. The SWCNTs were indicated based on the radial breathing mode (RBM) peak present between 200 - 300 raman shift (cm^-1). The diameters of synthesized CNTs ranged between 54 - 200 nm. Raman spectrum revealed that the G-bands were 1569, 1582 and 1576 cm^-1, respectively, whereas the D-bands were 1346, 1350 and 1358 cm^-1 for SWCNT synthesis at 700, 800 and 900 °C, respectively. The modified CVD method set up in the present study was successfully used for large scale synthesis of CNTs from an aqueous precursor such as fermented tapioca liquid.

Abstract: Herb have been the basis of traditional medicines throughout the world for thousands of years and continue to provide new remedies to humankind In this study, Polygonum minus (kesum) nanoparticles were prepared by using planetary ball mill and analysis for their physical and morphology properties. The size reduction method had a distinct effect on physical and morphology properties of Polygonum minus analyzed. The surface morphology and roughness of nanoherb was analyzed by using Field Emission Scanning Electron Microscope (FSEM) and Atomic Force Microscope (AFM). The result showed that after ball milling, the average size of particles was produced in range 227-241nm which was significantly smaller than the 100 μm prepared by conventional rotor mixer. Higher degree of granule surface fractured was observed as a result of a planetary ball milling process based on FESEM images.

Abstract: The a-C:B film were prepared by mixing vapor of hydrocarbon palm oil, boron dopant, carrier gas, and argon in the chamber deposited at -30 V and -50 V of negative bias voltage. The effect of these negative bias voltage on the thickness, electrical and electronic properties of a-C:B film were investigated. It was observed, the optical band gap slightly changed (2.0 eV to 2.04 eV). The fabricated solar cell with the configuration of Au/p-C:B/n-Si/Au achieved conversion efficiency (η) of 0.192% at applied bias voltage of -50 V. This result showed by the applied of negative bias voltage can controlled the interstitial doping of boron in the amorphous carbon films network.

Abstract: The effect of deposition subtrate temperatures by the applied of constant -20 V on electrical and optical properties of in-situ boron-doped amorphous carbon films were determined. From Tauc’s plot, optical band gap (𝐸𝑔) was determined, and 𝐸𝑔 decreased as deposition temperature increased (1.99 eV to 1.90 eV) while the resistivity values were slowly deteriorates from 1.84x10⁶ Ωcm to 4.31x10⁵ Ωcm. The highest and lowest efficiecny of Au/a-C:B/n-Si/Au devices were achieved at 350°C (0.063641 %) and 200°C (0.042691 %), respectively. It can be concluded that by comparing with deposition temperature ranging from 200°C to 350°C under deposition condition used, at 350°C showed the optimum value for solar cell applications.

Abstract: Abstract. Investigation on the plasma properties is an essential fundamental works in order to precisely control the growth of nanoscale thin film. In the present work, we produced and study the reactive magnetron sputtering plasma in Ar+O₂ ambient using a solid Zn target as sputter source. We evaluate the electron temperature, electron density and ion density using Langmuir probe measurement as a function of O₂ flow rate and working pressure. We found that the electron temperature increased spontaneously with the oxygen flow rate. The electron temperature was almost doubled when O₂ flow rate increased from 0 sccm to 10 sccm. The electron and ion densities increased with the oxygen flow rate between 0 sccm and 5 sccm. However, after 5 sccm of O₂ flow rate which is approximately 11% of O₂/(O₂+Ar) flow rate ratio the electron density decreased drastically. This is due to the electron attachment and the production of negative ion species in Ar+O₂ plasma environment. In addition, we found that the ion flux increase monotonically with the O₂ flow rate thus will increase the ion bombardment effect on the deposited thin film and eventually damage the thin film. Our experimental results suggest that the O₂ flow rate and the working pressure would have a significant influence on ion bombardment effect on deposited thin film.

Abstract: Porous silicon nanostructures (PSiN) are nanoporous materials which consist of uniform network of interconnected pore. The structure of PSiN is depending on etching parameters, including current density, HF electrolyte concentration, substrate doping type and level. In this work, the results of a structural p-type and n-type of porous silicon nanostructures were investigated by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) is reported. Samples were prepared by photo-electrochemical anodization of p- and n-type crystalline silicon in HF electrolyte at different etching time. The surface morphology of PSiN was studied by FESEM with same magnification shown n-type surface form crack faster than p-type of PSiN. While the topography and roughness of PSiN was characterize by AFM. From topography shown the different etching time for both type PSiN produce different porosity and roughness respectively. There is good agreement between p- and n-type have different in terms of surface characteristic.

Abstract: Nanoparticles are now essential material to be used in material engineering, medicine and cosmetic application due to their chemical, mechanical and optical properties. Several experiments were designed to investigate the relationship effect of bead size using different bead size (4 mm and 2 mm) at fix grinding conditions. Changes in particles size produce were studied using dynamic light scattering method at 25 °C. The z-Average and polydipersity index for each particles size at different grinding were recorded. Using smaller size of zirconia bead will produced smaller size of C. asiatica than using larger bead size. As a result the smallest size particle by mean is 242 nm where 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition at 517 nm shows the smaller particles has a higher percentage of inhibition.