S. M. Kahar

Synthesis of Silicon Carbide Nanowhiskers from Graphite and Silica of Different Ratio by Microwave Irradiation Assisted Synthesis

In this paper, the effect of ratio of silicon dioxide and graphite for the synthesis of silicon carbide nanowhiskers by microwaves heating was reported. The mixtures of SiO2 and graphite with different ratio were prepared by ultrasonic mixing using ethanol as medium. The mixtures were dried on hotplate and cold pressed by using hydraulic hand press uniaxially into a pellet die. The mixture in the form of pellet were heated up to 1400 °C at heating rate of 20 °C/min and soaked for 30 minutes. Scanning electron microscopy was used to study the morphology of sample of each different ratio of mixture. It was found that almost complete conversion of graphite and silica to silicon carbide nanowhiskers was observed for sample of mixture SiO2 and graphite in the ratio of 1:3. Result from x-ray diffraction analysis also indicated that single β-SiC phase was present in the diffractogram of silicon carbide nanowhiskers synthesized from mixture SiO2 and graphite in the ratio of 1:3.

Fabrication and characterization of spiral interdigitated electrodes based biosensor for salivary glucose detection

This work introduces the non-invasive glucose monitoring technique by using the Complementary Metal Oxide Semiconductor (CMOS) technologically fabricated spiral Interdigitated Electrodes (IDE) based biosensor. Scanning Electron Microscopy (SEM) image explores the morphology of spiral IDE while Energy Dispersive X-Ray (EDX) determines the elements induced in spiral IDE. Oral saliva of two patients are collected and tested on the spiral IDE sensor with electrical characterization as glucose detection results. However, both patients exhibit their glucose level characteristics inconsistently. Therefore, this work could be extended and enhanced by adding Glutaraldehyde in between 3-Aminoproply)triethoxysilane (APTES) modified and glucose oxidase (GOD) enzyme immobilized layer with FTIR validation for bonding attachment.

Fabrication and characterization on width of spiral interdigitated electrodes based biosensors

Simple and inexpensive mask layout design on a transparency film were demonstrated using the conventional complementary metal oxide semiconductor (CMOS) technique to produce interdigitated electrodes (IDEs) for biomedical biosensors applications. Lift-off techniques were implemented during photolithography process in order to pattern an electrode widths of 200µm, 300µm, 400µm and 500µm, respectively with a standardized 400µm gap spacing spiral IDEs. Due to the effect of the transparent mask, a fabrication of these spiral IDEs resulted in shrinkage of electrode width and increment of the gap spacing. Among these electrode sizes, the conductance of 300µm, 400µm and 500µm electrode width were successfully examined as compared to 200µm.

Synthesis of SiC nanowhiskers from graphite and silica by microwave heating

Abstract Silicon carbide (SiC) is an important ceramics for engineering and industrial applications due to its advantage to withstand in high temperatures. In this article, a demonstration of SiC nanowhiskers synthesis by using microwave heating has been shown. The mixtures of raw materials in the form of pellets were heated, using a laboratory microwave furnace, to 1400 °C for 40 minutes at a heating rate of 20 °C/min. The characterization process proved that the mixture of graphite and silica in the ratio of 1:3 is an ideal composition for synthesizing single phase β-SiC nanowhiskers. Vapor-solid mechanism was suggested to explain the formation of SiC nanowhiskers by the proposed microwave heating.

Characterization of Silicon Carbide Nanowhiskers Synthesized by Microwave Heating Using Photoluminescence Spectroscopy and Fourier Transform Infrared Spectroscopy

Silicon carbide is an attractive material for engineering and industrial applications in harsh conditions. In manufacturing process, conventional heating process is commonly used to synthesis the silicon carbide. In this study, SiC nanowhiskers were synthesized from microwave heating of mixture of graphite and silica in the ratio of 3: 1. The mixture was heated by using laboratory microwaves oven to 1400°C at heating rate of 20 °C/min and temperature was hold for 30 minutes. Photoluminescence spectroscopy and Fourier transform infrared spectroscopy were used to characterize the SiC nanowhiskers. Photoluminescence spectrum of SiC nanowhiskers showed a sharp peak at 420 nm corresponding to band gap of SiC (2.39 ev). FTIR absorption spectra of SiCNWs recorded a band at 805.22 cm-1 corresponding to Si-C bond.

Impact of gate workfunction in junctionless versus junction SOI n-MOSFET transistor

In this paper, the effect of gate workfunction variation on DC characteristics in 100 nm gate length silicon-on-insulator (SOI) junctionless (JL) and junction transistors has been investigated by using numerical simulations. The digital figure-of-merits characteristics such as threshold voltage (VTH), on/off-current ratio, subthreshold voltage, and drain-induced-barrier-lowering are the main parameters that have been investigated. The rate of change in VTH with the respect to gate workfunction for both JLT and JT devices was almost same. Besides that, it shows the designated JLT device is achieving full-depletion at higher gate workfunction of more than 5.0 eV whereas the designated JT device is more wider range, ranging from low, mid-gap or high workfunction.

Impact of size variation in junctionless vs junction planar SOI n-MOSFET transistor

In this paper, the effect of silicon body thickness (TSi) and silicon body width (WSi) variation on DC characteristics in 100 nm gate length silicon-on-insulator (SOI) junctionless (JL) and junction transistors has been investigated by using numerical simulations. The digital figure-of-merits characteristics such as threshold voltage (VTH), on-current, subthreshold voltage, and drain-induced-barrier-lowering are the main parameters that have been investigated. Based on the simulations, the JT device is less sensitive to variation of TSi and WSi compared to JLT.

Electron concentration behavior in junctionless vs junction SOI n-MOSFET transistor

In this paper, the effect of gate workfunction variation on electron concentration at depletion and inversion as a function of applied gate voltage for 100 nm gate length silicon-on-insulator (SOI) junctionless (JLT) and junction (JT) transistors are investigated. It shows that the JLT device is properly function and achieving full-depletion without losing gate controllability at higher gate workfunction of more than 5.0 eV whereas the designated JT device is more wider range, ranging from low, mid-gap or high workfunction.

Microwave irradiation assisted synthesis of silicon carbide nanowhiskers

Conventional methods for the synthesis of silicon carbide were well studied and these methods included carbothermal reduction, mechanical milling, sol-gel process and others. However, conventional methods have limitations such as high energy consumption, presence of impurities and long reaction times. In this paper, microwave heating was applied for the first time for the synthesis of silicon carbide nanotube owing to the advantages of microwave heating such as shorter reaction time, uniform heat distribution and low cost. Mixture of silicon dioxide and carbon nanotube in the ratio of 1:3 as suggested by previous study were mixed in ultrasonic bath using ethanol as liquid medium for 2 hours and then dried on hot plate to evaporate ethanol. The mixture was then cold pressed into 3mm pellet and placed into an alumina crucible filled with silica sand acts as sand insulator and SiC susceptor. The pellet was heated to 1400°C with heating rate of 30°C/min for 40 minute. X-ray diffraction pattern verified the presence of single β-SiC phase in silicon carbide nanotubes. Meanwhile, scanning electron microscopy revealed that tubular structure of carbon nanotube was retained after microwave irradiation and energy dispersive x-ray spectroscopy shown the silicon carbide nanotube consist of only elemental C and Si and thus indicated that silicon carbide nanotubes were successfully synthesized through microwave irradiation.