Papers by Author: Muhammad Azmi Abd Hamid

Abstract: Thin films of copper oxide were successively deposited on glass substrates by sol-gel like spin coating for 40 s and annealed in air at different temperatures (200-400°C). Precursor solutions were prepared by dissolving cupric chloride in methanol. Various stabilizers and additives were used to enhance the solubility of cupric chloride and to improve the adhesion between the films and the glass substrates. Glucopone was used as a surfactant to reduce the surface energy. The evolution of oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction and scanning electron microscopy. Annealing the films in air at 300°C converts the films to CuO. The general appearances of the films were uniform and brownish in color.

Abstract: Cuprous oxide (Cu₂O) thin films were successfully grown on indium tin oxide (ITO) coated glass by sol-gel spin coating using diethanolamine (DEA) as a solubility agent. The films were annealed at 350 °C in 5% H₂ + 95% N₂ atmosphere. The films were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Based on the SEM micrograph of the as obtained film, the film shows better coverage with the four sided pyramidal shape grain size of 108 nm. The prepared Cu₂O thin film was used as an active electrode for photoelectrochemical cell of ITO/Cu₂O/PVC-LiClO₄/graphite. The photovoltaic cell was tested using current-voltage characteristic under light illumination of 100 mW/cm².

Abstract: This paper deals with the current transport mechanism of solid state photoelectrochemical cells of ITO/Cu₂O/PVCLiClO₄/graphite as well as the physical properties of a component of a device affecting its performance. The principle of operation used in the photoelectrochemical cells is presented. The device makes use of ITO films, Cu₂O films, PVCLiClO₄ and graphite films as photoanode, photovoltaic material, solid electrolyte and counter electrode, respectively. The device shows rectification. The J_sc and V_oc obtained at 100 mW cm² were 3.2 x 10^-11 mA/cm² and 0.92 V, respectively.

Abstract: Grape-like tin dioxide (SnO₂) structures have been grown on p-type silicon (Si(100)) substrate synthesized by thermal evaporation of tin (Sn) without use of metal catalyst. The experiment were conducted in a three-zone tube furnace at a constant temperature of 1080°C,under 1.6% of oxygen (O₂) gas in an atmospheric ambient with a controlled flow rate of 1.0L/min. The prepared SnO₂ film was characterized by using X-ray diffraction diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy(EDX) and photoluminescence (PL) measurement. The grape-like SnO₂ structures were highly crystalline with particle size (resemble grape fruit) ranging from 120-550 nm and diameter of wire (resemble grape stem) around 120-160 nm.The PL spectrum of the grape-like SnO₂ structures exhibits a broad visible light emission with a peak centered at around 623 nm, corresponding to 1.99 eV and usual near band edge emission of SnO₂ is not observed.

Abstract: Cuprous oxide (Cu₂O) thin films were formed onto three different substrates such as indium tin oxide (ITO) coated glass, titanium oxide (TiO₂) and n-Si substrates by sol-gel spin coating technique. It was found that the formation mechanism of Cu₂O films onto different substrates lead to different microstructures. The films were characterized by field-emission scanning electron microscopy (FESEM). Based on the FESEM micrographs the grain shape of film prepared were different on ITO, TiO₂ and n-Si substrate with 114 nm, 154 nm and 84 nm respectively. The results indicate that the choice of substrate strongly affect the film morphology, structural and optical properties. Keywords: Cu₂O, thin films, ITO, sol-gel, microstructures

Abstract: Zinc oxide nanorods were grown on Si (100) and Platinum coated glass substrate by the aqueous chemical growth (ACG) in aqueous solution that contained zinc nitrate hexahydrate (Zn(NO3)2•6H20) and hexamethylenetetramine (C6H12N4). The obtained ZnO nanorods are uniformly distributed on the Platinum coated glass substrate surface from 1.5 h to 3 h growth time. Branched hexagonal rods were also found growth on these uniform nanorods. Branched hexagonal rods were found on Si (100) from 2 h to 3 h growth time. A small number of flower-like structures compared to the majority oval type structure suggest that secondary nucleation had occurred during the process of growth. All of the high intensity peaks, including the strong (101) peak, are assigned to wurtzite ZnO hexagonal indicating that the product is pure ZnO. The results found in this study revealed that the type substrate plays a role in determining the surface morphology of ZnO growth.

Abstract: This paper discusses the effect of two similar gold wire (wire A and wire B) used mainly as a wire bonding material for Quad Flat Nolead (QFN) package. Both wires with diameter of 25.4 μm were bonded using automatic wire bonder by maintaining the temperature at 200°C. The effect of trace elements on the mechanical properties of 4N gold wire has not been widely investigated for some years despite the important of wire-bonding and the move towards fine pitch applications. Due to the element analysis, atomic percentage of Ca in wire B is higher than wire A. Pull strength increase with the increasing of the trace element. The higher pull strength of wire B could improve the yield strength, elastic modulus and recrytallization temperature.

Abstract: A tin-lead solder is generally used to mount an electronic package on to a printed circuit board (PCB) of an electronic devices. In this study, we investigated the microstructure of the solder joint from a four years old used mobile phone. Microstructure and morphology of the joint was obtained using optical and scanning electron microscopy (OM and SEM) respectively. Cracks and voids can clearly be seen in the solder area for the most of the sample observed. Crack up to 10 μm wide appeared to be propagating along the solder line between Cu lead and Cu substrate. Energy dispersive X-ray (EDX) analysis revealed that cracks occurred at the richer tin content. It was not clear the exact mechanism that leads to the existence of the crack. However we believe that thermomechanical cause such as thermal fatigue, void formation and the thicker layer of intermetallic compound contributed to the failure of the solder joint.