• Title/Summary/Keyword: device degradation

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A Study on Wafer Level Vacuum Packaging using Epi poly for MEMS Applications (Epi poly를 이용한 MEMS 소자용 웨이퍼 단위의 진공 패키징에 대한 연구)

  • 석선호;이병렬;전국진
    • Journal of the Semiconductor & Display Technology
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    • v.1 no.1
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    • pp.15-19
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    • 2002
  • A new vacuum packaging process in wafer level is developed for the surface micromachining devices using glass silicon anodic bonding technology. The inside pressure of the packaged device was measured indirectly by the quality factor of the mechanical resonator. The measured Q factor was about 5$\times10^4$ and the estimated inner pressure was about 1 mTorr. And it is also possible to change the inside pressure of the packaged devices from 2 Torr to 1 mTorr by varying the amount of the Ti gettering material. The long-term stability test is still on the way, but in initial characterization, the yield is about 80% and the vacuum degradation with time was not observed.

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Study on the Breakdown Simulation for InAlAs/InGaAs/GaAs MHEMTs with an InP-etchstop Layer (InP 식각정지층을 갖는 InAlAs/InGaAs/GaAs MHEMT 소자의 항복 특성 시뮬레이션에 관한 연구)

  • Son, Myung Sik
    • Journal of the Semiconductor & Display Technology
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    • v.11 no.2
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    • pp.53-57
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    • 2012
  • This paper is for accurately simulating the breakdown of MHEMTs with an InP-etchstop layer. 2D-Hydrodynamic simulation parameters are investigated and calibrated for the InP-epitaxy layer. With these calibrated parameters, simulations are performed and analyzed for the breakdown of devices with an InP-etchstop layer. In the paper, the impact-ionization coefficients, the mobility degradation due to doping concentration, and the saturation velocity for InP-epitaxy layer are newly calibrated for more accurate breakdown simulation.

The Threshold Voltage and the Effective Channel Length Modeling of Degraded PMOSFET due to Hot Electron (Hot electron에 의하여 노쇠화된 PMOSFET의 문턱전압과 유효 채널길이 모델링)

  • 홍성택;박종태
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.8
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    • pp.72-79
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    • 1994
  • In this paper semi empirical models are presented for the hot electron induced threshold voltage shift(${\Delta}V_{t}$) and effective channel shortening length (${\Delta}L_{H}$) in degraded PMOSFET. Trapped electron charges in gate oxide are calculated from the well known gate current model and ΔLS1HT is calculated by using trapped electron charges. (${\Delta}L_{H}$) is a function of gate stress voltage such as threshold voltage shift and degradation of drain current. From the correlation between (${\Delta}L_{H}$) has a logarithmic function of stress time. From the measured results, (${\Delta}V_{t}$) and (${\Delta}L_{H}$) are function of initial gate current and device channel length.

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A study on Fabrication and Characterization of Organic Light-Emitting Diodes (유기 발광 다이오드의 제작 및 특성에 관한 연구)

  • Lee, Han-Seong
    • Proceedings of the KIEE Conference
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    • 2008.11b
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    • pp.89-91
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    • 2008
  • Organic EL has been expected to adopt to a new styles of technology that make flat display after Tang & Vanslyke made good electric luminescence device in late 1980s. Their studies based on multi layer structure that consists of emitting layer and carrier transporting layer using proper organic material. But oxidization of organic layer by ITO, energy walls in both pole interface, contaminations of ITO surface, importance of protecting membrane, diffusive dimming of light to cathode organic layer, these causes of degradations are common facts of a macromolecule and micro molecule. We think these degradation caused by the impact of heat and electro-chemical factor, bulk effect and interface phenomenon, and raise a question.

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The Characteristics of a Dual gate Trench Emitter IGBT (이중 Gate를 갖는 Trench Emitter IGBT의 특성)

  • Gang, Yeong-Su;Jeong, Sang-Gu
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.9
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    • pp.523-526
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    • 2000
  • A dual gate trench emitter IGBT structure is proposed and studied numerically using the device simulator MEDICI. The on-state forward voltage drop latch-up current density turn-off time and breakdown voltage of the proposed structure are compared with those of the conventional DMOS-IGBT and trench gate IGBT structures. The proposed structure forms an additional channel and increases collector current level resulting in reduction of on -state forward voltage drop. In addition the trench emitter increases latch-up current density by 148% in comparison with that for the conventional DMOS-IGBT and by 83% compared with that for the trench gate IGBT without degradation in breakdown voltage when the half trench gate width(Tgw) and trench emitter depth(Ted) are fixed at $1.5\mum\; and\; 2\mum$, respectively

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A Study on the Hot-Carrier Effects of p-channel poly-Si TFT (p-채널 po1y-Si TFT 소자의 Hot-Carrier효과에 관한 연구)

  • 진교원;박태성;이제혁;백희원;변문기;김영호
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1997.11a
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    • pp.266-269
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    • 1997
  • Hot carrier effects as a function of bias stress time and bias stress conditions were syste-matica1ly investigated in p-channel po1y-Si TFT's fabricated on the quartz substrate. The device degradation was observed for the negative bias stress. After positive bias stressing, Improvement of electrical characteristic except for subthreshold slope was observed. It was found that these results were related to the hot carrier injection into the gate oxide and interface states at the poly-Si/SiO$_2$interface rather than defects states generation under bias stress.

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On resistance and breakdown voltage of LDMOS with Multi RESURF structure (Multi RESURF구조를 갖는 LDMOS의 on 저항과 항복전압)

  • Choi, E-Kwon;Choi, Yearn-Ik;Chung, Sang-Koo
    • Proceedings of the KIEE Conference
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    • 2002.11a
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    • pp.156-158
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    • 2002
  • Reduction of on-resistance($R_{on}$) in high voltage devices is of critical importance for the power consumption of the device. $R_{on}$ decreases with increase of the doping concentration of the drift region. However, breakdown voltage(BV) decreaes also with increase of doping concentration. In this report, a multi-resurf LDMOS[1] strcuture is proposed to reduce the $R_{on}$ which allows no degradation in BV. The on-and off-state characteristics of the proposed structure are simulated using the two-dimensional devices simulator ATLAS and compared with those from the conventional structure.

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Analysis of the breakdown degradation of thyristor due to the aging test (사이리스터의 가속열화에 따른 항복전압 특성)

  • Lee, Y.J.;Seo, K.S.;Kim, H.W.;Kim, K.H.;Kim, S.C.;Kim, N.K.;Kim, B.C.
    • Proceedings of the KIEE Conference
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    • 2005.07b
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    • pp.1512-1514
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    • 2005
  • 사이리스터의 파괴 원인에는 온도, 전압, 전류, 진동 및 압력 등이 있다. 본 논문에서는 이러한 파괴원인들 중에서 전압과 온도를 스트레스 인자로 하여 가속열화에 따른 소자의 항복전압 특성의 변화에 대해 실험을 통해 분석하였다. 실험에 사용한 사이리스터는 $V_{DRM}$=1800, $V_{RRM}$=2300V, $I_{DRM}$, $I_{RRM}$=20mA인 소자를 사용하였으며, 실험 시 인가전압은 1kV, 온도는 $100^{\circ}C$로 고정하였다. 가속열화에 따른 순방향 및 역방향 항복특성의 변화를 가속열화 시간에 따라 나타내었고, 이를 바탕으로 전압과 온도에 따른 항복전압 감소의 원인과 열화의 진행에 대해 기술하였다.

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A Distributed Coexistence Mitigation Scheme for IoT-Based Smart Medical Systems

  • Kim, BeomSeok
    • Journal of Information Processing Systems
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    • v.13 no.6
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    • pp.1602-1612
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    • 2017
  • Since rapidly disseminating of Internet of Things (IoT) as the new communication paradigm, a number of studies for various applications is being carried out. Especially, interest in the smart medical system is rising. In the smart medical system, a number of medical devices are distributed in popular area such as station and medical center, and this high density of medical device distribution can cause serious performance degradation of communication, referred to as the coexistence problem. When coexistence problem occurs in smart medical system, reliable transmitting of patient's biological information may not be guaranteed and patient's life can be jeopardized. Therefore, coexistence problem in smart medical system should be resolved. In this paper, we propose a distributed coexistence mitigation scheme for IoT-based smart medical system which can dynamically avoid interference in coexistence situation and can guarantee reliable communication. To evaluate the performance of the proposed scheme, we perform extensive simulations by comparing with IEEE 802.15.4 MAC protocol which is a traditional low-power communication technology.

Polymer Passivation Effect on Methylammonium Lead Halide Perovskite Photodetectors

  • Kim, Hyojung;Byun, Hye Ryung;Kim, Bora;Kim, Sung Hyuk;Oh, Hye Min;Jeong, Mun Seok
    • Journal of the Korean Physical Society
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    • v.73 no.11
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    • pp.1675-1678
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    • 2018
  • Methylammonium lead halide ($MAPbI_3$) perovskites are considered as promising materials owing to their excellent optical and electrical properties. However, perovskite materials suffer from degradation in air, which limits their practical applications. Here, we demonstrate successful passivation of the $MAPbI_3$ photodetectors through monochloro-para-xylylene (Parylene-C) deposition. The time-dependent photocurrent characteristics were systematically investigated, and we achieved significantly improved device performance and stability with Parylene-C passivation. Based on the excitation-power-dependent photoluminescence (PL) data, we confirmed that Parylene-C can reduce the carrier losses in $MAPbI_3$, leading to the enhancement of photocurrent and PL in $MAPbI_3$ photodetectors.