Jumiah Hassan

Electrical property comparison and charge transmission in p-type double gate and single gate junctionless accumulation transistor fabricated by AFM nanolithography

The junctionless nanowire transistor is a promising alternative for a new generation of nanotransistors. In this letter the atomic force microscopy nanolithography with two wet etching processes was implemented to fabricate simple structures as double gate and single gate junctionless silicon nanowire transistor on low doped p-type silicon-on-insulator wafer. The etching process was developed and optimized in the present work compared to our previous works. The output, transfer characteristics and drain conductance of both structures were compared. The trend for both devices found to be the same but differences in subthreshold swing, ‘on/off’ ratio, and threshold voltage were observed. The devices are ‘on’ state when performing as the pinch off devices. The positive gate voltage shows pinch off effect, while the negative gate voltage was unable to make a significant effect on drain current. The charge transmission in devices is also investigated in simple model according to a junctionless transistor principal.

Pinch-off mechanism in double-lateral-gate junctionless transistors fabricated by scanning probe microscope based lithography.

Summary A double-lateral-gate p-type junctionless transistor is fabricated on a low-doped (1015) silicon-on-insulator wafer by a lithography technique based on scanning probe microscopy and two steps of wet chemical etching. The experimental transfer characteristics are obtained and compared with the numerical characteristics of the device. The simulation results are used to investigate the pinch-off mechanism, from the flat band to the off state. The study is based on the variation of the carrier density and the electric-field components. The device is a pinch-off transistor, which is normally in the on state and is driven into the off state by the application of a positive gate voltage. We demonstrate that the depletion starts from the bottom corner of the channel facing the gates and expands toward the center and top of the channel. Redistribution of the carriers due to the electric field emanating from the gates creates an electric field perpendicular to the current, toward the bottom of the channel, which provides the electrostatic squeezing of the current.

Field effect in silicon nanostructure fabricated by Atomic Force Microscopy nano lithography

The electrical property of silicon nano-structure is highly considered in nanoelectronics. In this context we investigate the field effect in nanostructure Junctionless p-type silicon nanowire transistor under the lateral gate voltage. The device fabricated by means of Atomic Force microscopy (AFM) nano lithography on Silicon on Insulator (SOI) wafer. I-V characteristic and the Drain/Source current under the lateral gate voltage investigated. The subthreshold swing measured and hysteresis effect observed for the old sample compared to new one.

Morphology and dielectric properties of single sample Ni 0.5 Zn 0.5 Fe 2 O 4 nanoparticles prepared via mechanical alloying

Nickel-zinc ferrite nanoparticles are important soft magnetic materials for high and low frequency device application and good dielectric materials. Nickel-zinc ferrite nanoparticles with composition Ni0.5Zn0.5Fe2O4 were prepared using mechanical alloying to analyze the effect of sintering temperature on microstructure evolution of a single sample with dielectric properties. The single sample with nanosized pellet was sintered from 600 °C to 1200 °C and analyzed by X-ray diffraction (XRD) to investigate the phases of the powders and by field emission scanning electron microscopy (FESEM) for the morphology and microstructure analyses. Dielectric properties such as dielectric constant (ɛ′) and dielectric loss (ɛ″) were studied as functions of frequency and temperature for Ni0.5Zn0.5Fe2O4. The dielectric properties of the sample were measured using HP 4192A LF impedance analyzer in the low frequency range from 40 Hz to 1 MHz and at temperature ranging from 30 °C to 250 °C. The results showed that single phase Ni0.5Zn0.5Fe2O4 cannot be formed by milling alone and therefore requires sintering. The crystallization of the ferrite sample increased with increasing sintering temperature, while the porosity decreased and the density and average grain size increased. Evolution of the microstructure resulted in three activation energies of grain growth, where above 850 °C there was a rapid grain growth in the microstructure. Dielectric constant and loss factor decreased with the increase in frequency. The optimum sintering temperature of Ni0.5Zn0.5Fe2O4 was found to be 900 °C which had high dielectric constant and low dielectric loss.

Fast and Accurate Technique for Determination of Moisture Content in Oil Palm Fruits using Open-Ended Coaxial Sensor

A simple, fast and accurate technique employing an open-ended coaxial sensor for the determination of the moisture content in oil palm fruit is presented. For this technique, a calibration equation has been developed based on the relationship between the measured moisture content obtained by the oven drying method and the phase of the reflection coefficient of the sensor for 21 fruits. The moisture content predicted by the sensor was in good agreement with that obtained using the standard oven drying method within � 5% accuracy when tested on 145 different fruits samples. (DOI: 10.1143/JJAP.44.5272) Palm oil is now one of the worlds most popular edible oils. It is extracted from the flesh of oil palm fruits by a series of processes performed at a mill. The quality and quantity of the oil are functions of the ripeness of the fruit. Moisture content is one of the most important factors that influence the ripeness of oil palm fruit. 1) The measurement of moisture content using a microwave method is widely known to be accurate and rapid. However, not all microwave techniques are suitable for single fruit measurements due to the small sample size. It has been pointed out that a microstrip sensor 2) offers distinct advantages in this respect since only a small part of the sample interacts with the sensor and there is no restriction on the sample size. Unfortunately, use of the sensor requires laborious sample preparation in which the fresh mesocarp of the oil palm fruit has to be separated from the nut, cut into small pieces and crumbled to form a semi solid sample. In this article, we propose the use of an open-ended coaxial sensor to realize a simple, fast and accurate technique for the determination moisture content in oil palm fruits. In the near future, the sensor shall be incorporated in the development of a cost- effective portable microwave moisture meter operating at frequencies below 5 GHz. The open-ended sensor, as shown in Fig. 1, was fabricated from a 12.7 mm by 12.7 mm square flange, sub-miniature A type (SMA) coaxial stub contact panel. The dielectric material separating the gold-plated, stainless-steel inner and outer conductors of the coaxial line is PTFE. The diameters of the inner and outer conductors are 1.3 and 4.1 mm, respectively. The PTFE stub was machined flat and polished. The reflection coefficient of the oil palm fruits was measured using the sensor with a HP8720B Vector Network Analyzer (VNA). All calibrations and measurements were performed for 801 points in the frequency range between 1 and 5 GHz at room temperature in a stepped continuous-wave (CW) mode for which a synthesized frequency could be obtained for each data point. A full one-port calibration technique was implemented on the BB 0 plane using an HP 85052D 3.5 mm calibration kit. Under the assumption of a quasi-TEM mode, the measured reflection coefficientAA 0 of the fruit sample on the plane AA 0 can be de-embedded to the connector end of the probe which coincides with the calibration plane BB 0 to give a reflection coefficientBB 0 by the relation 3) � BB0 ¼ � AA0 expð jDÞ; ð1Þ whereis the propagation constant of the coaxial line section and D is the physical length of the coaxial line. Sampling was performed on fruits of various degrees of ripeness from twenty bunches from different 12-year-old oil palms of the tenera variety. Part of the fresh mesocarp of each fruit was sliced in the longitudinal direction to ensure good contact between the surface of the mesocarp and the sensor. The nondestructive testing of fruits can be accom- plished in the future by using an open-ended coaxial sensor with inner and outer conductors of small diameter. The true moisture content of the fruit samples was determined using the standard oven drying method. 4) A set of 21 fruits was used to establish the calibration equation relating the true moisture content to the phase of the reflection coefficient. The reliability of the calibration equation was tested using another set of 145 different fruits. Figure 2 clearly shows a linear relationship between the true moisture content (mc) of the oil palm fruits and the phase of the reflection coefficient, � . Due to the large number of frequency points, only representative frequency points, namely 1, 2, 3, 4 and 5 GHz, are shown in the graph. The coefficients A and B along with their R-squared values found using the linear regression model,

Fabrication of p-Type Double Gate and Single Gate Junctionless Silicon Nanowire Transistor by Atomic Force Microscopy Nanolithography

In this work, we have investigated the fabrication of Double gate and Single gate Junctionless silicon nanowire transistor using silicon nanowire patterned on lightly doped (105 cm-3) p-type Silicon on insulator wafer fabricated by Atomic force microscopy nanolithography technique. Local anodic oxidation followed by two wet etching steps, Potassium hydroxide etching for Silicon removal and Hydrofluoric acid etching for oxide removal, were implemented to reach the structures. Writing speed and applied tip voltage were held in 0.6 µm/s and 8 volt respectively for Cr/Pt tip. Scan speed was held in 1.0 µm/s. The etching processes were elaborately performed and optimized by 30%wt. Potassium hydroxide + 10%vol. Isopropyl alcohol in appropriate time, temperature and humidity. The structure is a gated resistor turned off based on a pinch-off effect principle, when essential positive gate voltage is applied. Negative gate voltage was unable to make significant effect on drain current to drive the device into accumulation mode.

Bianchi Type III String Cosmological Models for Perfect Fluid Distribution in General Relativity

Some geometrical aspects of Bianchi type III space‐time are investigated. This is followed by the study of Bianchi type III string cosmological models with perfect fluid distribution of matter.

Development and Design of Microstrip Moisture Sensor for Rice Grain

This paper deals with the analysis and design of a microstrip sensor for accurate determination of moisture content (MC) in rice grains. The sensor consists of four layers- RT-Duroid substrate, protective layer, wet medium as a sensing area, and air. A functional relationship has been developed between microwave attenuation of the sensor and moisture content in grains for four layered semi-infinite microstrip structure, and close agreement has been found between computed and experimental results. The analysis of electromagnetic wave propagation in the sensor structure is simply represented and prediction of dielectric properties of rice grains is given by a dielectric mixture model. This work also studies the effect of thicknesses of protective layer on the sensitivity of the sensor. The sensor is suitable for development as a complete instrument and to estimate the optimum moisture content of rice grains, more quickly and accurately

Study of the side gate junctionless transistor in accumulation region

Purpose The purpose of this paper is to analyse the operation of p-type side gate junctionless silicon transistor (SGJLT) in accumulation region through experimental measurements and 3-D TCAD simulation results. The variation of electric field components, carrier’s concentration and valence band edge energy towards the accumulation region is explored with the aim of finding the origin of SGJLT performance in the accumulation operational condition. Design/methodology/approach The device is fabricated by atomic force microscopy nanolithography on silicon-on-insulator wafer. The output and transfer characteristics of the device are obtained using 3-D Technology Computer Aided Design (TCAD) Sentaurus software and compared with experimental measurement results. The advantages of AFM nanolithography in contact mode and Silicon on Insulator (SOI) technology were implemented to fabricate a simple structure which exhibits the behaviour of field effect transistors. The device has 200-nm channel length, 100-nm gate gap and 4 μm for the distance between the source and drain contacts. The characteristics of the fabricated device were measured using an Agilent HP4156C semiconductor parameter analyzer (SPA). A 3-D TCAD Sentaurus tool is used as the simulation platform. The Boltzmann statistics is adopted because of the low doping concentration of the channel. Hydrodynamic model is taken to be as the main transport model for all simulations, and the quantum mechanical effects are ignored. A doping dependent Masetti mobility model was also included as well as an electric field dependent model with Shockley–Read–Hall (SRH) carrier recombination/generation. Findings We have obtained that the device is a normally on state device mainly because of the lack of work functional difference between the gate and the channel. Analysis of electric field components’ variation, carrier’s concentration and valence band edge energy reveals that increasing the negative gate voltage drives the device into accumulation region; however, it is unable to increase the drain current significantly. The positive slope of the hole quasi-Fermi level in the accumulation region presents mechanism of carriers’ movement from source to drain. The influence of electric field because of drain and gate voltage on charge distribution explains a low increasing of the drain current when the device operates in accumulation regime. Originality/value The proposed side gate junctionless transistors simplify the fabrication process, because of the lack of gate oxide and physical junctions, and implement the atomic force microscopy nanolithography for fabrication process. The optimized structure with lower gap between gate and channel and narrower channel would present the output characteristics near the ideal transistors for next generation of scaled-down devices in both accumulation and depletion region. The presented findings are verified through experimental measurements and simulation results.

Effect of Variation Sintering Temperature on Magnetic Permeability and Grain Sizes of Y3Fe5O12 via Mechanical Alloying Technique

This work will focus on the preparation of yttrium iron garnet (Y3Fe5O12, YIG) via mechanical alloying technique derive by steel waste product. The Fe2O3 powder derived from the steel waste purified by using magnetic and non-magnetic particles (MNM) and Curie temperature separation (CTS) technique. The purified powder was then oxidized in air at 500 °C for 9 hours in air. The Fe2O3 was mixed with Y2O3 using high energy ball milling for 9 hours. The mixed powder obtained was pressed and sintered at different temperature 500/600/700/800/900/1000/1100 °C. X-ray diffraction (XRD) shows the YIG is completely form at 1100 °C. The field emission scanning electron microscopy (FESEM) images shows the grain size increases as increase the sintering temperatures. The frequency dependence on the complex permeability, µ’ and magnetic loss, µ’’ in the frequency range 10 MHz to 1 GHz were measured in this study. The results showed that the highest μ΄ is 5.890 obtained from 1100 °C.