Fabrication And Characterization Of Porous Iii-Nitrides Alloys For Application In Hydrogen Gas Sensing Devices

Matlamat kajian yang dibentangkan adalah untuk memfabrikasikan struktur berliang III-nitrida dan menggunakannya untuk aplikasi peranti penderia gas hydrogen The main goal of this work was to fabricate porous III-nitrides structures and utilize them in hydrogen gas sensing device

Fabrication and characterization of 0.24 micron CMOS device by using simulation / Nazirah Mohamat Kasim, Rosfariza Radzali and Ahmad Puad Ismail

Simulation and analyzing the electrical characteristics of 0.24 micron CMOS device was done by using Silvaco TCAD. Electrical characteristics were carried out by using Atlas device simulator, while for simulation the process was carried out by using Athena process simulator to modify theoretical values and obtain more accurate process parameters. The electrical parameter was extracted to investigate the device characteristics. Several design analyses were performed to investigate the effectiveness of the advanced method in order to prevent the varying of threshold voltage. The electrical characteristics produce the graph of drain current versus drain voltage, lᴅ-Vᴅ and drain current versus gate voltage, lᴅ-Vɢ. From lᴅ-Vɢ can be obtained the threshold voltage, Vᴛ in which Vᴛ for NMOS transistor is lower than Vᴛ for PMOS transistor which is 0.6695V and -0.9683 V respectively. The gate length Lɢ obtained from the simulation for NMOS and PMOS is the same which is 0.235 micron and it is nearest to the scale for this research work

Dielectric properties assessment of honey by using non-destructive dielectric spectroscopy

In this research the dielectric constant of three types of Malaysian honey has been investigated using a non-destructive measurement technique. The objective of this research is to assess the dielectric constant of the three types of honey in Malaysia using a non-destructive measurement technique known as an open-ended coaxial probe in the frequency range from 100 MHz to 10 GHz frequency. Analysis on the effect water concentration in honey on the dielectric constant and the effect of temperature on dielectric constant of honey has been conducted. The three types of honey that have been chosen to be investigated in this project are stingless bee honey, wild honey and commercial (organic) honey and together their water adulterated samples. For this research, the probe had been set up by setting a range of frequency from 100 MHz to 10 GHz and needs to be calibrated with three calibration methods namely open, short and reference water. From the result it was found that the higher the temperature of the honey and the higher percentage of water content in the honey, the dielectric constant is increased. The dielectric constants of all honeys decreased with increasing frequency in the measured frequency range and increased with increase percentage of water content and temperature

Influence Of Etching Time On The Porous P-Type Gallium Nitride Using Alternating Current Photo-Assisted Electrochemical Etching Technique

The Theoretical And Experimental Study Of Porous P-Type Gallium Nitride (Gan) Is Discussed In This Work. Porous P-Type Gan Was Adequately Fabricated Using Alternating Current Photo-Assisted Electrochemical Etching Technique With Various Etching Times (10, 20, 30, And 60 Minutes) In Mixed Hydrofluoric Acid And Ethanol Electrolyte Solutions (1:4 Volume Ratios) Under Ultraviolet Illuminations. The Evolution Of Morphology Of Non-Porous And Porous P-Type Gan As A Function Of Etching Time Was Imaged Using Field Emission Scanning Electron Microscopy Measurement. Surface Analysis Revealed A Sporadic Pore Size With Circular Shape Was Found In Porous P-Type Gan While Smooth And No Pores Was Observed In Non-Porous P-Type Gan Sample. Etching For A Brief Time Frame Resulted In Small Pores, And Etching For Longer Times Resulted In Enormous Pores. However, Prolonged Etching Times Of 60 Minutes Would Prompt Breakdown Of Porous Layer. The Average Pore Diameter And Porosity Of The Investigated Samples Were Estimated From The Imagej Software. Subsequent Effort By Investigating The Structural Characteristics Of Non-Porous And Porous Samples By Variety Of Methods, Including High Resolution X-Ray Diffraction And Atomic Force Microscopy. A Significant Increase In The Surface Roughness Was Observed With An Increase In The Etching Time. The Discoveries Found That The Influence Of Etching Duration Has Indicated Noteworthy Impacts Towards Morphological And Structural Properties Of The Porous P-Type Gan, As Supportively Revealed Through Pore Size, Porosity, And Surface Roughness

Influence Of Etching Time On The Porous P-Type Gallium Nitride Using Alternating Current Photo-Assisted Electrochemical Etching Technique

The theoretical and experimental study of porous p-type gallium nitride (GaN) is discussed in this work. Porous p-type GaN was adequately fabricated using alternating current photo-assisted electrochemical etching technique with various etching times (10, 20, 30, and 60 minutes) in mixed hydrofluoric acid and ethanol electrolyte solutions (1:4 volume ratios) under ultraviolet illuminations. The evolution of morphology of non-porous and porous p-type GaN as a function of etching time was imaged using field emission scanning electron microscopy measurement. Surface analysis revealed a sporadic pore size with circular shape was found in porous p-type GaN while smooth and no pores was observed in non-porous p-type GaN sample. Etching for a brief time frame resulted in small pores, and etching for longer times resulted in enormous pores. However, prolonged etching times of 60 minutes would prompt breakdown of porous layer. The average pore diameter and porosity of the investigated samples were estimated from the ImageJ software. Subsequent effort by investigating the structural characteristics of non-porous and porous samples by variety of methods, including high resolution x-ray diffraction and atomic force microscopy. A significant increase in the surface roughness was observed with an increase in the etching time. The discoveries found that the influence of etching duration has indicated noteworthy impacts towards morphological and structural properties of the porous p-type GaN, as supportively revealed through pore size, porosity, and surface roughnes

Enhancing Performance of Porous Si-Doped GaN based MSM Photodetector Using AC Technique

In this work, we report the formation of porous Si-doped GaN films under a novel alternating current (sine-wave a.c. (50 Hz)) photo-assisted electrochemical etching (ACPEC) conditions. The formation of porous Si-doped GaN by the novel ACPEC is performed in the same electrolyte concentration (4% KOH) used in common de constant current electrochemical etching process. Ultra-violet (UV) illumination is used to assist in the generation of electron-hole pairs, where etching proceeds through the oxidation and consequently, dissolution of the semiconductor surface. The ac formed porous Si-doped GaN with excellent structural and optical properties. According to the FESEM micrographs, the GaN thin films exhibit a homogeneous nanoporous structures with spatial nano-flakes arrangement. The porous layer exhibited a substantial photoluminescence (PL) intensity enhancement with red-shifted band-edge PL peaks associated with the relaxation of compressive stress. The shift of E2(high) to the lower frequency in Raman spectra of the porous GaN films further confirms such a stress relaxation. Electrical characterizations of the MSM photodiodes were carried out by using current-voltage (1-V) measurements indicated that the devices were highly sensitive to ambient light

Enhancing Performance Of Porous Si-Doped GaN Based Msm Photodetector Using 50 Hz Acpec

In this work, we report the formation of porous Si-doped GaN films under a novel alternating current (sine-wave a.c. (50 Hz)) photo-assisted electrochemical etching (ACPEC) conditions. The formation of porous Si-doped GaN by the novel ACPEC is performed in the same electrolyte concentration (4% KOH) used in common dc constant current electrochemical etching process. Ultra-violet (UV) illumination is used to assist in the generation of electron-hole pairs, where etching proceeds through the oxidation and consequently, dissolution of the semiconductor surface. The ac formed porous Si-doped GaN with excellent structural and optical properties. According to the FESEM micrographs, the GaN thin films exhibit a homogeneous nanoporous structures with spatial nano-flakes arrangement. The porous layer exhibited a substantial photoluminescence (PL) intensity enhancement with red-shifted band-edge PL peaks associated with the relaxation of compressive stress. The shift of E2(high) to the lower frequency in Raman spectra of the porous GaN films further confirms such a stress relaxation. Electrical characterizations of the MSM photodiodes were carried out by using current-voltage (I-V) measurements indicated that the devices were highly sensitive to ambient light

Enhanced catalytic palladium embedded inside porous silicon for improved hydrogen gas sensing

In this work, we reported on room temperature porous silicon (PS) and embedding PS using simple and economical techniques of electrochemical etching and thermal evaporation. The PS substrate was prepared using the technique of electrochemically etching the n-type Si (100) wafer at a constant current density of 10 mA/cm2 for 10 min under the illumination of incandescent white light. After PS formation, Ge pieces were thermally evaporated onto the two PS substrates in a vacuum condition. This was then followed by the deposition of the ZnO layer onto the Ge/PS substrate by the same method using commercial 99.9% pure ZnO powders. The three samples were identified as PS, Ge/PS and ZnO/Ge/PS samples, respectively. Pd finger contacts were deposited on the PS and embedding PS (Ge/PS and ZnO/Ge/PS) to form Pd on PS hydrogen sensors using RF magnetron sputtering. SEM and EDX suggested the presence of substantial Ge and ZnO inside the uniform circular pores for Ge/PS and ZnO/Ge/PS samples, respectively. Raman spectra showed that good crystalline Ge and ZnO nanostructures embedded inside the pores were obtained. For hydrogen sensing, Pd on ZnO/Ge/PS Schottky diode exhibited a dramatic change of current after exposure to H2 as compared to PS and Ge/PS devices. It is observed that the sensitivity increased exponentially with the hydrogen flow rate for all the sensors. The ZnO/Ge/PS showed more sensitivity towards H2 than that of PS and Ge/PS especially at high flow rate of H2 with higher current gain (69.11) and shorter response (180 s) and recovery times (30 s)

Small scale integrated renewable energy supply for remote office employing the use of PV source / Nor Salwa Damanhuri … [et al.]

In order to overcome the running-out of the non-renewable sources, world has been introduced to the application of renewable energy. Renewable energy is defined as the energy which is generated from natural resources such as wind, sunlight, water, geothermal and many more. Wind energy is one the way to generate electricity. To utilize wind as energy source, the system need to be installed in the area consist of airflow to run the turbine. Unfortunately, Malaysia is not suitable to implement the wind energy system because lack of strong airflow [1]. Hydropower is also another renewable energy source. Usually, a hydropower is generated from dam. When the dam is constructed, it may generate the electricity at a constant rate and the lake formed from the dam construction can be used for water sports and leisure. However, the drawback of hydropower system is that the dam construction is extremely expensive to build. The dam also invites flooding to the area nearby and will destroy the living in villages and town [2]

Study of low dimensional SiGe island on Si for potential visible Metal-Semiconductor-Metal photodetector

In this paper, an investigation of design and simulation of silicon germanium (SiGe) islands on silicon (Si) was presented for potential visible metal semiconductor metal (MSM) photodetector. The characterization of the performances in term of the structural, optical and electrical properties of the structures was analyzed from the simulation results. The project involves simulation using SILVACO Technology Computer Aided Design (TCAD) tools. The different structures of the silicon germanium (SiGe) island on silicon substrate were created, which were large SiGe, small SiGe, combination SiGe and bulk Ge. All the structures were tested for potential Metal Semiconductor Metal (MSM) photodetector. The extracted data such as current versus voltage characteristic, current gain and spectral response were obtained using ATLAS SILVACO tools. The performance of SiGe island structures and bulk Ge on Si substrate as (MSM) photodetector was evaluated by photo and dark current-voltage (I-V) characteristics. It was found that SiGe islands exhibited higher energy band gap compared to bulk Ge. The SiGe islands current-voltage characteristics showed improved current gain compared to bulk Ge. Specifically the enhancement of the islands gain was contributed by the enhanced photo currents and lower dark currents. The spectral responses of the SiGe islands showed peak response at 590 nm (yellow) which is at the visible wavelength. This shows the feasibility of the SiGe islands to be utilized for visible photodetections