M. Jagadesh Kumar and C. Linga Reddy
To develop a silicon lateral Schottky rectifier with low forward voltage drop and low reverse leakage current while its breakdown voltage is significantly larger than that of a…
Abstract
Purpose
To develop a silicon lateral Schottky rectifier with low forward voltage drop and low reverse leakage current while its breakdown voltage is significantly larger than that of a conventional Schottky rectifier.
Design/methodology/approach
A two‐dimensional device simulation has been used, to examine the effect lateral dual sidewall Schottky concept on the current‐voltage characteristics of a lateral Schottky rectifier on silicon‐on‐insulator. The Schottky contact consists of a low‐barrier metal and a high‐barrier metal.
Findings
Results show that, during forward bias, the low‐barrier Schottky (LBS) contact conducts resulting in a low forward voltage drop. During the reverse bias, the LBS contact is shielded by the depletion region of the high‐barrier Schottky contact resulting in a low reverse leakage current.
Practical implications
With this approach, silicon Schottky rectifiers with low power dissipation and improved breakdown voltage can be realized.
Originality/value
The proposed device has a large commercial potential as a low‐power high‐voltage switching device.
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Sukhendu Deb Roy and M. Jagadesh Kumar
The main purpose of this paper is to find a simple method to improve the breakdown voltage of BJTs fabricated on SOI.
Abstract
Purpose
The main purpose of this paper is to find a simple method to improve the breakdown voltage of BJTs fabricated on SOI.
Design/methodology/approach
We have used two‐dimensional device simulation to examine the effect of a collector tub on the collector breakdown of the SOI based BJTs. This method involves creating a collector tub by etching the buried oxide followed by an n‐type implantation on the collector n/n+ junction side.
Findings
First, our method reduces the peak electric field at the silicon film‐BOX interface and secondly, the collector‐tub facilitates the collector potential to be absorbed by both collector drift and substrate regions improving the collector breakdown significantly.
Practical implications (if applicable)
An improved breakdown voltage improves the reliability of BJTs on SOI.
Originality/value
Our results show that the BVCEO of the bipolar transistors with a collector‐tub is enhanced by 2.7 times when compared with a conventional lateral bipolar transistor (LBT) with identical drift region doping. This improvement has an important practical value in the fabrication of SOI‐based LBTs.
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Himanshu Batwani, Mayank Gaur and M. Jagadesh Kumar
The purpose of this paper is to present an analytical drain current model for output characteristics of strained‐Si/SiGe bulk MOSFET.
Abstract
Purpose
The purpose of this paper is to present an analytical drain current model for output characteristics of strained‐Si/SiGe bulk MOSFET.
Design/methodology/approach
A physics‐based model for current output characteristics and transconductance of strained‐Si/SiGe bulk devices has been developed incorporating the impact of strain (in terms of equivalent Ge mole fraction), strained silicon thin film thickness, gate work function, channel length and other device parameters. The accuracy of the results obtained using this model is verified by comparing them with 2D device simulations.
Findings
This model correctly predicts the output characteristics, IDS−VGS characteristics, transconductance and output conductance of the strained‐Si/SiGe MOSFET and demonstrates a significant enhancement in the drain current of the MOSFET with increasing strain in the strained‐Si thin film, i.e. with increasing equivalent Ge concentration in the SiGe bulk.
Research limitations/implications
Can be implemented in a SPICE like simulator for studying circuit behaviour containing strained‐Si/SiGe bulk MOSFETs.
Practical implications
The model discussed in this paper can be easily implemented in a circuit simulator and used for the characterization of strained silicon devices. This complements the recent trend of investigation of new materials and device structures to maintain the rate of advancement in VLSI technology.
Originality/value
This paper presents, for the first time, a compact surface potential‐based analytical model for strained‐Si/SiGe MOSFETs which predicts the device characteristics reasonably well over their range of operation.
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Allowing foreign universities to operate autonomously would represent an overhaul of India’s higher education system. Commitment to the idea is a notable feature of the National…
Details
DOI: 10.1108/OXAN-DB275561
ISSN: 2633-304X
Keywords
Geographic
Topical
Pradeep Kumar Mishra and Jagadesh T.
The tensile behavior of additively manufactured nylon-based carbon fiber-reinforced composites (CFRP) is an important criterion in aerospace and automobile structural design. So…
Abstract
Purpose
The tensile behavior of additively manufactured nylon-based carbon fiber-reinforced composites (CFRP) is an important criterion in aerospace and automobile structural design. So, this study aims to evaluate and validate the tensile stiffness of printed CFRP composites (low- and high-volume fraction fiber) using the volume average stiffness (VAS) model in consonance with experimental results. In specific, the tensile characterization of printed laminate composites is studied under the influence of raster orientations and process-induced defects.
Design/methodology/approach
CFRP composite laminates of low- and high-volume fraction carbon fiber of different raster orientations (0°, ± 45° and 0/90°) were fabricated using the continuous fiber 3D printing technique, and tensile characteristics of laminates were done on a universal testing machine with the crosshead speed of 2 mm/min. The induced fracture surface of laminates due to tensile load was examined using the scanning electron microscopy technique.
Findings
The VAS model can predict the tensile stiffness of printed CFRP composites with different raster orientations at an average prediction error of 5.94% and 10.58% for low- and high-volume fiber fractions, respectively. The unidirectional CFRP laminate composite with a high-volume fraction (50%) of carbon fiber showed 50.79% more tensile stiffness and 63.12% more tensile strength than the low-volume fraction (26%) unidirectional composite. Fiber pullout, fiber fracture and ply delamination are the major failure appearances observed in fracture surfaces of laminates under tensile load using scanning electron microscopy.
Originality/value
This investigation demonstrates the novel methodology to study specific tensile characteristics of low- and high-volume fraction 3D printed CFRP composite.
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Pradeep Kumar Mishra and Jagadesh T.
This study aims to evaluate the low energy impact characteristics of 3D printed carbon fiber thermoplastic and thermoset polymer composite using the Izod impact test. The effects…
Abstract
Purpose
This study aims to evaluate the low energy impact characteristics of 3D printed carbon fiber thermoplastic and thermoset polymer composite using the Izod impact test. The effects of infill density are examined on the Izod impact properties of 3D printed thermoset polymer and thermoplastic composite specimens. Furthermore, a thorough investigation is conducted into the effect of heat treatment using a hot-air oven on both types of 3D printed composite specimens. To characterize the impact characteristics of each specimen, the fracture surfaces caused by impact load are inspected, and the fracture mechanism is studied using scanning electron micrographs.
Design/methodology/approach
Izod Impact specimens of thermoset (epoxy resin) and thermoplastic carbon fiber of different infill density (70, 75, 80, 85, 90 and 100%) are fabricated using the different fiber impregnation 3D printing process. To carry out the heat treatment process, printing of composites is done for each infill design from both thermoset and thermoplastic composites and the impact characteristics of specimens are evaluated on a pendulum test-rig using the ASTM D-256 standard. Using a scanning electron microscope, each fracture zone underwent four separate scanning processes, ranging in size from 2 µm to 100 µm.
Findings
The impact resistance of the 3D printed thermoset and thermoplastic composite material is significantly influenced by the type of fiber placement and infill density in the matrix substrate. Because of the weak interfacial strength between the layers of fiber and polyamide 6, the specimen printed with continuous fiber implanted at the part exhibited reduced impact resistance. At 75% infill density, the impact specimen printed with coextruded fiber showed the highest impact resistance with a 367.02% greater magnitude than the continuous fiber specimen with the same infill density.
Originality/value
This work presents a novel approach to analyze the low energy impact characteristics and three-dimensional printing of carbon fiber reinforced thermoplastic and carbon fiber reinforced thermoset and thermoplastic composite material.
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Pradeep Kumar Mishra, Periyaswamy Kalidas and Jagadesh T.
Inconel 718 is used in gas turbine engines for aerospace applications due to high creep resistance but generating a hole with good surface integrity is challenging because the γ′�…
Abstract
Purpose
Inconel 718 is used in gas turbine engines for aerospace applications due to high creep resistance but generating a hole with good surface integrity is challenging because the γ′′ interface is very strong so that slip is difficult in the grain boundary. So, the purpose of this work is to enhance the performance of drilling using a micro texture drill tool filled with solid lubricant.
Design/methodology/approach
Three different micro textures such as star shaped with 6-sharp apex, rectangular slots parallel and perpendicular to drill axis are created using laser on the drill tool. Deep cryogenic treatment is done on the textured tool to improve the strength and wear resistance before it is filled with solid lubricant. A detailed experimental investigation is performed to analyse the hole geometry and surface integrity of the drilled hole.
Findings
The accuracy of the drilled holes is enhanced in the star shaped texture drill tool over other textured and non-textured tools. A significant improvement in surface finish and hardness are observed and moreover cylindricity error, burr height of the hole is less for the above condition. It is also inferred that, at lower feed rate and higher speed produce hole with an accuracy of 96%.
Originality/value
Aerospace industry is focussing on improving the hole geometry and surface in Inconel 718. This work demonstrates the novel technique to improve drilling of Inconel 718 using laser textured tool filled by the solid lubricant.
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Suhang Yang, Tangrui Chen and Zhifeng Xu
Recycled aggregate self-compacting concrete (RASCC) has the potential for sustainable resource utilization and has been widely applied. Predicting the compressive strength (CS) of…
Abstract
Purpose
Recycled aggregate self-compacting concrete (RASCC) has the potential for sustainable resource utilization and has been widely applied. Predicting the compressive strength (CS) of RASCC is challenging due to its complex composite nature and nonlinear behavior.
Design/methodology/approach
This study comprehensively evaluated commonly used machine learning (ML) techniques, including artificial neural networks (ANN), random trees (RT), bagging and random forests (RF) for predicting the CS of RASCC. The results indicate that RF and ANN models typically have advantages with higher R2 values, lower root mean square error (RMSE), mean square error (MSE) and mean absolute error (MAE) values.
Findings
The combination of ML and Shapley additive explanation (SHAP) interpretable algorithms provides physical rationality, allowing engineers to adjust the proportion based on parameter analysis to predict and design RASCC. The sensitivity analysis of the ML model indicates that ANN’s interpretation ability is weaker than tree-based algorithms (RT, BG and RF). ML regression technology has high accuracy, good interpretability and great potential for predicting the CS of RASCC.
Originality/value
ML regression technology has high accuracy, good interpretability and great potential for predicting the CS of RASCC.
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Sinan Obaidat, Mohammad Firas Tamimi, Ahmad Mumani and Basem Alkhaleel
This paper aims to present a predictive model approach to estimate the tensile behavior of polylactic acid (PLA) under uncertainty using the fused deposition modeling (FDM) and…
Abstract
Purpose
This paper aims to present a predictive model approach to estimate the tensile behavior of polylactic acid (PLA) under uncertainty using the fused deposition modeling (FDM) and American Society for Testing and Materials (ASTM) D638’s Types I and II test standards.
Design/methodology/approach
The prediction approach combines artificial neural network (ANN) and finite element analysis (FEA), Monte Carlo simulation (MCS) and experimental testing for estimating tensile behavior for FDM considering uncertainties of input parameters. FEA with variance-based sensitivity analysis is used to quantify the impacts of uncertain variables, resulting in determining the significant variables for use in the ANN model. ANN surrogates FEA models of ASTM D638’s Types I and II standards to assess their prediction capabilities using MCS. The developed model is applied for testing the tensile behavior of PLA given probabilistic variables of geometry and material properties.
Findings
The results demonstrate that Type I is more appropriate than Type II for predicting tensile behavior under uncertainty. With a training accuracy of 98% and proven presence of overfitting, the tensile behavior can be successfully modeled using predictive methods that consider the probabilistic nature of input parameters. The proposed approach is generic and can be used for other testing standards, input parameters, materials and response variables.
Originality/value
Using the proposed predictive approach, to the best of the authors’ knowledge, the tensile behavior of PLA is predicted for the first time considering uncertainties of input parameters. Also, incorporating global sensitivity analysis for determining the most contributing parameters influencing the tensile behavior has not yet been studied for FDM. The use of only significant variables for FEA, ANN and MCS minimizes the computational effort, allowing to simulate more runs with reduced number of variables within acceptable time.