Advanced Materials Research Vol. 925

Abstract: This study reports on the preliminary investigations on the effect of Reactive Ion Etch (RIE) parameters on the surface characteristics of Al bond pad. Investigation is done employing Design of Experiment (DOE) method. Quantity of Oxygen, Argon, ICP power and BIAS power were varied to get 16 sets of recipes. This provides 16 samples with different combination of RIE parameters. Surface characteristics of the samples were analyzed using Atomic Force Microscopy (AFM).Data collected were in terms of Surface Roughness (RA), Peak Vs Valley (P-V) and Surface Root-Mean-Square Roughness (RMS). Result shows that combination of these RIE parameters does not vastly affect the surface characteristics of the Al bond pad.

Abstract: Conventional gold wire bonding to alunimium bond pads leads to the formation of intermetallic compound. Electroless Nickel Immersion Gold (ENIG) has been proposed as surface finish for aluminium bond pads to improve high temperature reliability. In order to create acceptable solder bumps prior to reflow process, a particular bump height for ENIG bumps need to be obtained. This paper reports the effects of chemical bath temperature in response to the bump height using a shorter process time. Analysis was done by using a design of experiment (DOE). The results suggest that higher temperature increases the bump height. Electroless nickel temperature has more influence to the bump height compared to immersion gold temperature.

Abstract: Design of Experiment (DOE) is a technique for optimizing process which has controllable inputs and measurable outputs. As a method of DOE, 2⁴ Full Factorial design is used to study the effect of Reactive Ion Etch towards the surface roughness of aluminum pad and effect of the roughness produced towards the contact angle. Surface roughness analysis is done using Atomic Force Microscop (AFM). Contact angle is measured using AutoCad software from the images captured from droplet test. This contact angles must be more than 90° for non-wetting profile or less than 90° for wetting profile. This work is also done to understand the interaction between the process parameters and how each parameters will affect the etch rate. The results are analyzed which shows that the increase in surface roughness produces an increase on the contact angle and vice versa.

Abstract: This investigation is dealing with adsorption of benzene compound from aqueous solution using a new carbon nanotube (CNT) synthesized from a fuel oil waste of power plants which identify by FE-SEM and TEM. It was found that a CNT has a very significant adsorption for benzene compared to that of non-activated carbon. The equilibrium adsorption data were analyzed using adsorption models of Langmuir, Freundlich and Temkin. The results showed that the model isotherms are fitting very well with the experimental data. Kinetic study was conducted and the results pointed out that a pseudo-first order model was represented the data. Values of the activation thermodynamic functions were calculated through equilibrium constants at different temperature. All values of Gibbs functions were negative with values of-1.6 and-13.0 kJmol^-1 for non-active and CNT respectively, while values of enthalpy and entropy were about-33kJmol^-1 and-65JK^-1 mol^-1 for CNT respectively. These results indicated that the adsorption process was feasible, spontaneous and exothermic.

Abstract: Zinc oxide (ZnO) is a wide band gap semiconductor material (3.37 eV) with numerous present applications such as varistors, surface acoustic wave devices and future biomedical applications. ZnO nanorods were grown under specific growth condition by an inexpensive and simple, chemical bath deposition method on ZnO seeded glass substrates. Study of the ZnO nanorods over different precursors, i.e zinc acetate dehydrate and zinc nitrate hexahydrate, and sonication period ranging from 0 to 120 seconds by field emission scanning electron microscope (FESEM), including the nanorod size and the surface morphology, will be demonstrated in this paper. Characterization of the ZnO film using both X-ray diffraction (XRD) and UV-Vis spectroscopy will be established in determining the optimal composition along with the optical properties, respectively.

Abstract: Malaysia is well-known as one of the main producer and exporter of palm oil. With the high production of crude palm oil (CPO), huge amount of empty fruit bunch was generated as by-products. The abundant amount of EFB produced required careful waste management procedures. Pyrolysis is thermochemical decomposition of biomass in inert environment towards its conversion into bio-oil, bio-char and gas. In this study, the pyrolysis of empty fruit bunch (EFB) was conducted using a fixed bed reactor. The pertinent process parameters such as pyrolysis temperature, particle sizes and heating rates were investigated via the determination of the percentage product yields such as bio-oil, bio-char and gas. The first series of experiment was conducted to determine the effect of pyrolysis temperatures. The final pyrolysis temperature was varied at 300, 400, 500, 600 and 700 °C at constant heating rates and the nitrogen flowrates of 30 °C/min and 100 cm³/min respectively. It was determined that at pyrolysis temperature of 500 °C maximum bio-oil yield of 35.00 % was obtained with bio-char and gas yield of 26.98 and 38.02% respectively. In the second series of experiment, the effect of particle sizen was studied. The EFB particle was varied at <125, 125-250, 250-500, 500-710 and 710-1000 μm. The pyrolysis temperature was fixed at 500 °C with nitrogen flowrate of 100 cm³/min and heating rate of 30 °C/min. It was determined that using EFB particle size of 250-500 μm, the maximum bio-oil of 38.52% was achieved with bio-char and gas yields of 25.06 % and 36.42% respectively. In the third series of experiment to determine the effect of heating rates, the heating rates was varied at 10, 20, 30, 40, 50 and 60 °C/min towards the final pyrolysis temperature of 500 °C with constant nitrogen flowrates of 100 cm³/min. The results obtained showed that the highest amount of bio-oil of 40.81% was obtained when the heating rate of 20 °C/min was used. The bio-char and gas yield obtained were 24.69% and 34.50% respectively.

Abstract: This paper reports on the effects of gold (Au) catalyst on the growth of zinc oxide (ZnO) nanostructures by thermal chemical vapor deposition (TCVD). The thickness of Au catalyst was varied from 5 to 15 nm. The Au catalyst was annealed at 500 °C prior to the deposition of ZnO nanostructures by thermal chemical vapor deposition (TCVD). The morphology of the Au catalyst at different thickness and also ZnO nanostructures were characterized by field emission scanning electron microscopy (FESEM). The material component and crystalline properties of ZnO nanostructures were determined using Energy Dispersive X-ray spectroscopy (EDX) and also Raman Spectroscopy respectively. We found that the shape of the deposited ZnO nanostructures were different on different thickness of Au catalyst. There was no growth of ZnO on the 5 nm thick Au observed by FESEM and supported by EDX due to very small amount of Zn. On the 10 and 15 nm thick Au, growth of ZnO nanostructures were clearly observed.

Abstract: The paper presents the memristive behaviour of spin-coated titania thin films on ITO substrate. The sample was annealed in air ambient at different annealing temperature and duration of 250 and 450 °C for 20 and 60 min. The effect of post-annealing process to the physical thickness and crystallinity of the films towards switching behaviour was studied. It was found that the thickness and crystallinity of the films increases as the post annealing process increases. Sample annealed at 250 °C for 20 min with thinner film showed better switching behaviour even though the sample is still in amorphous form. Thus, in our work, we believed that the crystallinity of the films does not affect the switching behaviour of the sample. The reliability of device performance was studied by repeating the measurement for three times.

Abstract: In this work, we reported the photocatalytic activities of carbon nitride (CN) materials for removal of various aromatic organic pollutants under visible light irradiation. Both bulk carbon nitride (BCN) and mesoporous carbon nitride (MCN) were prepared similarly through thermal polymerization of urea precursor, except that the mesoporous structure was generated onto the MCN via hard template approach using silica nanoparticles. Successful preparations of both BCN and MCN were suggested from various characterization techniques using XRD, DR UV-Visible spectroscopy, nitrogen adsorption-desorption analyzer, and TEM. The prepared BCN and MCN were tested for removal of aromatic organic pollutants, which were benzene, phenol and salicylic acid under visible light irradiation. Both BCN and MCN did not exhibit any photocatalytic activities in the removal of benzene, but active for removals of phenol and salicylic acid. The structure stability and the presence of electron donating group on the organic pollutants were proposed to affect the photocatalytic removal reactions. Owing to the larger BET specific surface area, MCN showed much higher photocatalytic activity than the BCN for removal of phenol and salicylic acid.

Abstract: Aniline is a toxic organic pollutant that is abundantly present in the environment. One of approaches to remove the aniline is by adsorption process. In this study, mesoporous carbon nitride (MCN) was proposed for the first time to be a potential adsorbent for aniline. The adsorption studies were carried out at room temperature on the aniline solution with various initial concentrations for both bulk carbon nitride (BCN) and MCN. Owing to its larger surface area, the MCN showed much higher adsorption capacity towards aniline compared to the BCN. This result indicated that adsorbent with large surface area is very crucial in the adsorption of aniline. Comparison study was also carried out using mesoporous silica, MCM-41, which was reported to act as a good adsorbent for aniline. The adsorption capability of MCN was found to be higher than that of MCM-41. It was suggested that the MCN with larger pore diameter might have more suitable and favourable adsorption sites for aniline compared to MCM-41. This study obviously showed that MCN would be a new potential adsorbent for removal of aniline.