• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.611-613
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• 2016

The characteristics of tunnel field-effect transistor(TFET) structure with source-overlapped gate was investigated using a TCAD simulations. Tunneling is mostly divided into line-tunneling and point-tunneling, and line-tunneling is higher performance than point-tunneling in terms of subthreshold swing(SS) and on-current. In this paper, from the simulation results of source-overlapped gate length effects at silicon(Si), germanium(Ge), Si-Ge hetero TFET structure, the guideline of optimal structure with highest performance are proposed.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.4
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• pp.201-208
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• 1996

This paper proposes an efficient method for improving the training performance of the neural network using a hybrid of backpropagation algorithm and dynamic tunneling system.The backpropagation algorithm, which is the fast gradient descent method, is applied for high-speed optimization. The dynamic tunneling system, which is the deterministic method iwth a tunneling phenomenone, is applied for blobal optimization. Converging to the local minima by using the backpropagation algorithm, the approximate initial point for escaping the local minima is estimated by the pattern classification, and the simulation results show that the performance of proposed method is superior th that of backpropagation algorithm with randomized initial point settings.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.869-875
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• 2017

Using TCAD simulation, performances of tunnel field-effect transistors (TFETs) was investigated. Drain current-gate voltage types of TFET structure such as single-gate TFET (SG-TFET), double-gate TFET (DG-TFET), L-shaped TFET (L-TFET), and Pocket-TFET (P-TFET) are simulated, and then as dielectric constant of gate oxide and channel length are varied their subthreshold swing (SS) and on-current ($I_{on}$) are compared. On-currents and subthreshold swings of the L-TFET and P-TFET structures with high electric constant and line tunneling were 10 times and 20 mV/dec more than those of the SG-TFET and DG-TFET using point tunneling, respectively. Especially, it is shown that hump effect which dominant current element changes from point tunneling to line tunneling, is disappeared in P-TFET with high-k gate oxide such as $HfO_2$. The analysis of 4 types of TFET structure provides guidelines for the design of new types of TFET structure which concentrate on line tunneling by minimizing point tunneling.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.876-884
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• 2017

The current-voltage characteristics of Silicon(Si), Germanum(Ge), and hetero tunnel field-effect transistors(TFETs) with source-overlapped gate structure was investigated using TCAD simulations in terms of tunneling. A Si-TFET with gate oxide material $SiO_2$ showed the hump effects in which line and point tunneling appear simultaneously, but one with gate oxide material $HfO_2$ showed only the line tunneling due to decreasing threshold voltage and it shows better performance than one with gate oxide material $SiO_2$. Tunneling mechanism of Ge and hetero-TFETs with gate oxide material of both $SiO_2$ and $HfO_2$ are dominated by point tunneling, and showed higher leakage currents, and Si-TFET shows better performance than Ge and hetero-TFETs in terms of SS. These simulation results of Si, Ge, and hetero-TFETs with source-overlapped gate structure can give the guideline for optimal TFET structures with non-silicon channel materials.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.740-749
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• 1998

This paper proposes compression of image data using neural networks based on conjugate gradient method and dynamic tunneling system. The conjugate gradient method is applied for high speed optimization .The dynamic tunneling algorithms, which is the deterministic method with tunneling phenomenon, is applied for global optimization. Converging to the local minima by using the conjugate gradient method, the new initial point for escaping the local minima is estimated by dynamic tunneling system. The proposed method has been applied the image data compression of 12 ${\times}$12 pixels. The simulation results shows the proposed networks has better learning performance , in comparison with that using the conventional BP as learning algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.11
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• pp.891-898
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• 2003

Unmanned remote survey system is proposed to measure distance and angle of the present position of micro-tunneling machine from any starting point of entrance. Cross type linear LED that can be controlled remotely is attached to the tunneling machine. Range finder and angle measuring devise fixed to internal of the pipe can scan the center of LED. Distance and angle measuring devises are disposed in the measurable position of the pipe, then the present position of tunneling machine can be calculated automatically from the measurements.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.164-169
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• 2008

The effects of the antisite related defects on the electronic structure of silica and the gate leakage current have been investigated using first-principles calculations. Energy levels related to the antisite defects in silicon dioxide have been introduced into the bandgap, which are nearly 2.0 eV from the top of the valence band. Combining with the electronic structures calculated from first-principles simulations, tunneling currents through the silica layer with antisite defects have been calculated. The tunneling current calculations show that the hole tunneling currents assisted by the antisite defects will be dominant at low oxide field whereas the electron direct tunneling current will be dominant at high oxide field. With increased thickness of the defect layer, the threshold point where the hole tunneling current assisted by antisite defects in silica is equal to the electron direct tunneling current extends to higher oxide field.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.156-161
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• 2017

This work presents a novel structure for junction-less tunneling field effect transistor (JL-TFET) with a floating gate over the source region. Introduction of floating gate instead of fixed metal gate removes the limitation of fabrication process suitability. The proposed device is based on a heavily n-type-doped Si-channel junction-less field effect transistor (JLFET). A floating gate over source region and a control-gate with optimized metal work-function over channel region is used to make device work like a tunnel field effect transistor (TFET). The proposed device has exhibited excellent ID-VGS characteristics, ION/IOFF ratio, a point subthreshold slope (SS), and average SS for optimized device parameters. Electron charge stored in floating gate, isolation oxide layer and body doping concentration are optimized. The proposed JL-TFET can be a promising candidate for switching performances.

• Journal of information and communication convergence engineering
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• v.19 no.4
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• pp.263-268
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• 2021

Although the compact capacitance model of point tunneling types of tunneling field-effect transistors (TFET) has been proposed, those of line tunneling types of TFETs have not been reported. In this study, a compact capacitance model of an L-shaped TFET (LTFET), a line tunneling type of TFET, is proposed using the previously developed surface potentials and current models of P- and L-type LTFETs. The Verilog-A LTFET model for simulation program with integrated circuit emphasis (SPICE) was also developed to verify the validation of the compact LTFET model including the capacitance model. The SPICE simulation results using the Verilog-A LTFET were compared to those obtained using a technology computer-aided-design (TCAD) device simulator. The current-voltage characteristics and capacitance-voltage characteristics of N and P-LTFETs were consistent for all operational bias. The voltage transfer characteristics and transient response of the inverter circuit comprising N and P-LTFETs in series were verified with the TCAD mixed-mode simulation results.

• Journal of Magnetics
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• v.16 no.2
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• pp.169-172
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• 2011

This study reports an alternative method for measuring the magnetoresistance of unpatterned magnetic tunnel junctions similar to the current-in-plane tunneling (CIPT) method. Instead of using microprobes, a series of point contacts with different spacings are coated on the top surface of the junctions and R-H loops at various spacings are then measured by the usual four-point probe method. The values of magnetoresistance and resistance-area products can be obtained by fitting the measured data to the CIPT theoretical model. The test results of two types of junctions were highly similar to those obtained from standard CIPT tools. The proposed method may help to accelerate the process for evaluating the quality of magnetic tunnel junctions when commercial CIPT tools are not accessible.