Sang-Sik Choi
Chonbuk National University
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Featured researches published by Sang-Sik Choi.
Semiconductor Science and Technology | 2011
Sang-Sik Choi; Deok-Ho Cho; Chel-Jong Choi; Jong-Suk Kim; Jong-Han Yang; Kyu-Hwan Shim
The electrostatic discharge (ESD) stability of GaN-based LEDs, which are assembled with new transient voltage suppression (TVS) Zener diodes, has been characterized in experiments on reverse leakage current and functionality. Advantageous features of TVS Zener diodes with extremely low differential resistance and low leakage current have enhanced their ESD protection capability, especially at high temperature. The TVS Zener presented an excellent performance in protecting GaN-based LEDs from ESD stress exceeding the human body model ±8 kV at 110 °C. The ESD robustness of the high-temperature stability is analyzed in order to provide proper reliability under hostile environment of massive heat and light delivered from LEDs.
international symposium on consumer electronics | 2014
Daoheung Bouangeune; Young Joo Song; Sengchanh Vilathong; Sang-Sik Choi; Deok-Ho Cho; Chel-Jong Choi; Kyu-Hwan Shim
New ultra low capacitance bidirectional transient voltage suppression (Bi-TVS) devices consist of two parallel unidirectional TVS devices facing opposite directions, have been fabricated for electrostatic discharge (ESD) protection applications. The reduced pressure chemical vapor deposition (RPCVD) technology allows growing uniform thin Si films with various doping conditions and thicknesses of a PIN and TVS diode in one die. This result in a small turn on dynamic resistance of ~0.7 Ω and leakage current below 10-9 A. The employing PIN diode was effective in reducing the capacitance that suppressed down to ~0.6 pF and in leading to the wide signal band pass over 3 GHz. The fabricated Bi-TVS device was capability handled the IEC 610004-2 peak voltage and TLP current in exceeding ±29 kV and ±30 A. The research results guarantee that the new proposed TVS device is very effective in protecting high speed data line against strong and rapid ESD attacks.
international symposium on consumer electronics | 2014
Daoheung Bouangeune; Young Joo Song; Sengchanh Vilathong; Sang-Sik Choi; Deok-Ho Cho; Chel-Jong Choi; Kyu-Hwan Shim
New RC-Pi type ESD/EMI filters were fabricated using the integrated passive devices technology. Unique TVS diodes were employed to improve the electrostatic discharge (ESD) strength of the filters without sacrificing capacitance. The fabricated filter device has a cut off frequency of 270 MHz and the attenuation higher than -30 dB at >1 GHz. ESD testing results demonstrated the filter was capable withstand ±10 kV of IEC 61000-4-2 and handle positive TLP current up to 19 A. This evidence that excellent ESD performance can be found in the filter consist of the small TVS diode dimension of 50×50 μm2. The research results guide that employing TVS diodes are effective in the protection of data communication applications from very strong ESD shocks and noise disturbs.
IEICE Transactions on Electronics | 2008
Sang-Sik Choi; A-Ram Choi; Jae-Yeon Kim; Jeon-Wook Yang; Yong-Woo Hwang; Tae-Hyun Han; Deok Ho Cho; Kyu-Hwan Shim
The stress effect of SiGe p-type metal oxide semiconductor field effect transistors (MOSFETs) has been investigated to compare their properties associated with the Si0.88Ge0.12/Si epi channels grown on the Si bulk and partially depleted silicon on insulator (PD SOI) substrates. The stress-induced changes in the subthreshold slope and the drain induced barrier lowering were observed small in the SiGe PD SOI in comparison to in the SiGe bulk. Likewise the threshold voltage shift monitored as a function of hot carrier stress time presented excellent stability than in the SiGe PD SOI. Therefore, simply in terms of do properties, the SiGe PD SOI looks more immune from electrical stresses than the SiGe bulk. However, the 1/f noise properties revealed that the hot carrier stress could introduce lots of generation-recombination noise sources in the SiGe PD SOI. The quality control of oxide-silicon in SOI structures is essential to minimize a possible surge of 1/f noise level due to the hot carrier injection. In order to improve dc and rf performance simultaneously, it is very important to grow the SiGe channels on high quality SOI substrates.
Transactions on Electrical and Electronic Materials | 2016
Sakhone Pharkphoumy; Zagarzusem Khurelbaatar; Valliedu Janardhanam; Chel-Jong Choi; Kyu-Hwan Shim; Daoheung Daoheung; Bouangeun Bouangeun; Sang-Sik Choi; Deok-Ho Cho
Copyright ©2016 KIEEME. All rights reserved. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. pISSN: 1229-7607 eISSN: 2092-7592 DOI: http://dx.doi.org/10.4313/TEEM.2016.17.4.196 OAK Central: http://central.oak.go.kr
Journal of Semiconductor Technology and Science | 2014
Daoheung Bouangeune; Sang-Sik Choi; Deok-Ho Cho; Kyu-Hwan Shim; Sung-Yong Chang; See-Jong Leem; Chel-Jong Choi
Fast recovery diodes (FRDs) were developed using the epitaxial layers grown by low temperature epitaxy technology. We investigated the effect of electrostatic discharge (ESD) stresses on their electrical and switching properties using current-voltage (I-V) and reverse recovery time analyses. The FRDs presented a high breakdown voltage, >450 V, and a low reverse leakage current, A. From the temperature dependence of thermal activation energy, the reverse leakage current was dominated by thermal generation-recombination and diffusion, respectively, at low and high temperature regions. By virtue of the abrupt junction and the Pt drive-in for the controlling of carrier lifetime, the soft reverse recovery behavior could be obtained along with a well-controlled reverse recovery time of 21.12 ns. The FRDs exhibited excellent ESD robustness with negligible degradations in the I-V and the reverse recovery characteristics up to kV of HBM and kV of IEC61000-4-2 shocks. Likewise, transmission line pulse (TLP) analysis reveals that the FRDs can handle the maximum peak pulse current, , up to 30 A in the forward mode and down to - 24 A in the reverse mode. The robust ESD property can improve the long term reliability of various power applications such as automobile and switching mode power supply.
ieee global conference on consumer electronics | 2012
Daoheung Bouangeune; Woong-Ki Hong; Sang-Sik Choi; Chel-Jong Choi; Deok-Ho Cho; Kyu-Hwan Shim; Young-Gi Kim
A fully integrated LC-type ESD/EMI filter was developed by the integrated passive devices (IPD) technology. Unique TVS diodes are employed to enhance its performance while maintaining robust ESD characteristics. The reliability and performance of ESD/EMI filter are confirmed based on both attenuation and electrostatic discharge (ESD) strength which could be evaluated by insertion loss (S parameter), ESD and transmission line pulse (TLP) testing method. As the results, the device shows very low leakage current less than 1nA. Its ESD protection and attenuation could be robustness exceed 28 A TLP and ±17 kV IEC 61000-4-2 and achieved as >;35 dB at 800 MHz ~3 GHz, respectively. The cut off frequency obtained of 160 MHz that can ensure high-speed data communication applications.
IEICE Transactions on Electronics | 2008
A-Ram Choi; Sang-Sik Choi; Byung-Guan Park; Dongwoo Suh; Gyungock Kim; Jin-Tae Kim; Jin-Soo Choi; Deok Ho Cho; Tae-Hyun Han; Kyu-Hwan Shim
This paper presents the selective epitaxial growth (SEG) properties of reduced pressure chemical vapor deposition (RPCVD) at low temperatures (LT) of 675-725°C with high aspect ratio mask of dielectric films. The SEG process could be explained in conjunction with the loading effect, the mask pattern shape/size, and the process parameters of RPCVD. The growth rates showed a large non-uniformity up to 40% depending upon the pattern size of the dielectric mask films, but as the SEG film becomes thicker, the growth rate difference converged on -15% between the narrow 2-μm and the wide 100-μm patterns. The evolution of SEG was controlled dominantly by the surface migration control at the initial stage, and converted to the surface topology control. The design of pattern size and distribution with dummy patterns must be useful to accomplish the reliable and uniform LT-SEG.
Journal of The Korean Institute of Electrical and Electronic Material Engineers | 2007
A-Ram Choi; Sang-Sik Choi; Jun-Sik Kim; Seok-Nam Yoon; Sang-Hoon Kim; Kyu-Hwan Shim
This paper presents the electrical properties of SiGe HBTs designed with bottom collector and single metal layer structure for RF power amplifier. Base layer was formed with graded-SiGe/Si structures and the collector place to the bottom of the device. Bottom collector and single metal layer structures could significantly simplify the fabrication process. We studied about the influence of SiGe base thickness, number of emitter fingers and temperature dependence
Journal of The Korean Institute of Electrical and Electronic Material Engineers | 2007
Sang-Sik Choi; A-Ram Choi; Jae-Yeon Kim; Jeon-Wook Yang; Tae-Hyun Han; Deok-Ho Cho; Yong-Woo Hwang; Kyu-Hwan Shim
( frequency from measured data using packaged SiGe HBTs. We will discuss the temperature dependent current flow through the e-b, b-c junctions to understand stability and performance of the device.