• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.11-16
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• 2016

Silicon carbide (SiC) has received significant attention over the past decade because of its high-voltage, high-frequency and high-thermal reliability in devices compared to silicon. Especially, a SiC Schottky barrier diode (SBD) is most often used in low-voltage switching and low on-resistance power applications. However, electric field crowding at the contact edge of SBDs induces early breakdown and limits their performance. To overcome this problem, several edge termination techniques have been proposed. This paper proposes an improvement in the breakdown voltage using a double-field-plate structure in SiC SBDs, and we design, simulate, fabricate, and characterize the proposed structure. The measurement results of the proposed structure, demonstrate that the breakdown voltage can be improved by 38% while maintaining its forward characteristics without any change in the size of the anode contact junction region.

• Clean Technology
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• v.27 no.3
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• pp.223-231
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• 2021

In order to address many issues associated with large volume changes of silicon, which has very low electrical conductivity but offers about 10 times higher theoretical capacity than graphite (Gr), a silicon nanoparticles/hollow carbon (SiNP/HC) composite having bimodal-mesopores was prepared using silica nanoparticles as a template. A control SiNP/C composite without a hollow structure was also prepared for comparison. The physico-chemical and electrochemical properties of SiNP/HC were analyzed by X-ray diffractometry, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption measurements for surface area and pore size distribution, scanning electron microscopy, transmission electron microscopy, galvanostatic cycling, and cyclic voltammetry tests to compare them with those of the SiNP/C composite. The SiNP/HC composite showed significantly better cycle life and efficiency than the SiNP/C, with minimal increase in electrode thickness after long cycles. A hybrid composite, SiNP/HC@Gr, prepared by physical mixing of the SiNP/HC and Gr at a 50:50 weight ratio, exhibited even better cycle life and efficiency than the SiNP/HC at low capacity. Thus, silicon/carbon composites designed to have hollow spaces capable of accommodating volume expansion were found to be highly effective for long cycle life of silicon-based composites. However, further study is required to improve the low initial coulombic efficiency of SiNP/HC and SiNP/HC@Gr, which is possibly because of their high surface area causing excessive electrolyte decomposition for the formation of solid-electrolyte-interface layers.

• Journal of the Korean Electrochemical Society
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• v.16 no.2
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• pp.85-90
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• 2013

Graphite is a commercial anode material to have the specific capacity of 372 mAh/g and the true density of 2.2 g/ml. Many effort had been pouring to find out the better material than graphite. Good candidates are silicon, tin, etc. Zinc is also a plausible candidate to have the specific capacity of 412 mAh/g and the true density of 7.14 g/ml. In this study, the Zn based anode material including indium and nickel as minor additives was synthesised. In order to get the homogeneouly mixed Zn-In-Ni composite material, the sol-gel method was used. The anode prepared by Zn-In-Ni composite material has the $1^{st}$ specific capacity of 910 mAh/g. Through prolonged charge-discharge cycling, the specific capacities were reduced to 365 (at $31^{st}$ cycle) and 378 mAh/g (at $62^{th}$ cycle). The $1^{st}$ Ah efficiency was 45% and Ah efficiencies were exhibited at the prolonged cycle.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.1-13
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• 2014

Lithium ion batteries (LIBs) are the state-of-the-art technology among electrochemical energy storage and conversion cells, and are still considered the most attractive class of battery in the future due to their high specific energy density, high efficiency, and long cycle life. Rapid development of power-hungry commercial electronics and large-scale energy storage applications (e.g. off-peak electrical energy storage), however, requires novel anode materials that have higher energy densities to replace conventional graphite electrodes. Germanium (Ge) and silicon (Si) are thought to be ideal prospect candidates for next generation LIB anodes due to their extremely high theoretical energy capacities. For instance, Ge offers relatively lower volume change during cycling, better Li insertion/extraction kinetics, and higher electronic conductivity than Si. In this focused review, we briefly describe the basic concepts of LIBs and then look at the characteristics of ideal anode materials that can provide greatly improved electrochemical performance, including high capacity, better cycling behavior, and rate capability. We then discuss how, in the future, Ge anode materials (Ge and Ge oxides, Ge-carbon composites, and other Ge-based composites) could increase the capacity of today's Li batteries. In recent years, considerable efforts have been made to fulfill the requirements of excellent anode materials, especially using these materials at the nanoscale. This article shall serve as a handy reference, as well as starting point, for future research related to high capacity LIB anodes, especially based on semiconductor Ge and Si.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1585-1587
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• 2004

이중 에피층 구조를 가지는 SOI(Silicon-On-Insulator) LIGBT(Lateral Insulated Gate Bipolar Transistor)의 에피층 두께 변화에 따른 항복전압 특성을 분석하였다. 제안된 소자는 전하보상효과를 얻기 위해 n/p-epi의 이중 에피층 구조를 사용하였으며, 에피층 전체에 걸쳐서 전류가 흐를 수 있도록 하기 위해 trenched anode구조를 채택하였다. 본 논문에서는 n/p-epi층의 농도를 고정시킨 후 각각의 epi층의 두께를 변화시켜가며 simulation을 수행하였을 때 항복전압의 변화 및 표면과 epi층에서의 전계분포변화를 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.171.1-171.1
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• 2015

Carbon nanotube emitters is very promising electron emitter for electron beam applications. We introduced the carbon nanotube electron beam (C-beam) exposure technic using triode structure. As a source, the electron beam emit from CNT emitters placed at the cathode by high electric field. Through the gate mesh, with high accelerating energy, the electron can be extracted easily and impact at the anode plate. For thin film modification, after the C-beam exposure on the amorphous silicon thin film, we found phase changes and it showed a high crystallinity from the Raman measurement. We expect that this crystallized film will be a good candidate as a new active layer of TFT.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.171-175
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• 1996

Gate insulator for Si field emitter is usually formed by e-beam evaporation. However, the evaported oxide requires densification for a stable process and a reduction of gate leakage which results from its Si-rich and nonstoicheiometric structure. In this study, we have developed the process technology able to densify the evaporated oxide in H$_{2}$O ambient. Using this process, we have fabricted thefield emitter array with 625 emitters per pixel, of which gate hole diameter is 1.4.mu.m, for the pixel, anode current of 14.3.mu.A was extracted at a gate bias of 100V and gate leakage was about 0.27% of the total emission current.

• Carbon letters
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• v.16 no.3
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• pp.135-146
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• 2015

Graphite can be classified into natural graphite from mines and artificial graphite. Due to its outstanding properties such as light weight, thermal resistance, electrical conductivity, thermal conductivity, chemical stability, and high-temperature strength, artificial graphite is used across various industries in powder form and bulk form. Artificial graphite of powder form is usually used as anode materials for secondary cells, while artificial graphite of bulk form is used in steelmaking electrode bars, nuclear reactor moderators, silicon ingots for semiconductors, and manufacturing equipment. This study defines artificial graphite as bulk graphite, and provides an overview of bulk graphite manufacturing, including isotropic and anisotropic materials, molding methods, and heat treatment.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.17-20
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• 2002

This study has been investigated that traps generated inside of the oxide and at the oxide interfaces by the stress bias voltage. The traps are charged near the cathode with negative charge and charged near the anode with positive charge. The charge state of the traps can easily be changed by application of low voltages after the stress high voltage. These trap generation involve either electron impact ionization processes or high field generation processes. It determined to the relative traps locations inside the oxides ranges from 113.4A to 814A with capacitor areas of 10$^{-3}$ $\textrm{cm}^2$ The oxide charge state of traps generated by the stress high voltage contain either a positive or negative charge.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3274-3275
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• 1999

This paper presents a new method of spacer assembly using anodic bonding method which is very simple and clean. The spacer having $100{\mu}m(W){\times}2.1{\mu}m(H)$ was bonded on amorphous silicon film of anode plate. Then, the vertical-type electrode was used for assembling of spacer in high voltage field emission display. In these results, we suggested that the vertical-type electrode provided spacer alignment for high aspect ratio and more simple batch process than conventional method.