• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.799-805
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• 2004

Two dimensional MEDICI simulator is used to study the characteristics of latch-up current of Dual Gate Emitter Switched Thyristor. The simulation is done in terms of the current-voltage characteristics, latch-up current density, ON-voltage drop and electrical property with the variations of p-base impurity concentrations. Compared with the other power devices such as MOS Controlled Cascade Thyristor(MCCT), Conventional Emitter Switched Thyristor(C-EST) and Dual Channel Emitter Switched Thyristor(DC-EST), Dual Gate Emitter Switched Thyristor(DG-EST) shows to have the better electrical characteristics, which is the high latch-up current density and low forward voltage-drop. The proposed DG-EST which has a non-planer p-base structure under the floating $N^+$ emitter indicates to have the better characteristics of latch-up current and breakover voltage.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.236-236
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• 2010

단일접합 $n^+-p/p^+$ (p-emitter) 및 $p^+-n/n^+$ (n-emitter) GaAs 태양전지 (Solar Cell)를 각각 제작하여, 그 소자특성을 비교 분석하였다. AM 1.5 (1 sun, $100\;mW/cm^2$) 표준광을 조사할 경우, p-emitter/n-emitter 소자의 개방회로전압 (Voc), 단락회로전류 (Jsc), 충전율 (FF), 효율 (Eff)은 각각 0.910/0.917 V, $15.9/16.1\;mA/cm^2$, 78.7/78.9, 11.4/12.1%로서, n-emitter 소자가 다소 크지만 거의 비슷한 값을 가지고 있었다. 태양전지의 집광 특성을 분석하기 위하여 조사광의 출력에 따른 태양전지의 소자 특성을 측정하였다. 조사광 강도가 높아짐에 따라 p-emitter 소자의 특성은 점진적으로 증가하는 반면, n-emitter는 1.3 sun에서 약 1.4 배의 최대 효율 (17%)을 나타내고 조사광이 더 증가함에 따라 급격히 감소하는 특성을 보여 주었다. (그림 참고) 본 연구에서 사용한 2종류 소자의 층구조는 서로 반대되는 대칭구조로서, 모두 가까이에 위치하고 있는 표면전극 (surface finger) 방향으로 소수전하 (minority carrier)가 이동하고 다수전하 (majority carrier)는 기판 (두께 $350\;{\mu}m$)을 통한 먼 거리의 후면전극 (back electrode)으로 표류 (drift)되도록 설계되어 있다. 이때, n-emitter에서는 이동도 (mobility)와 확산길이 (diffusion length)가 높은 전자가 후면전극으로 이동하기 때문에 적정밀도의 전자-정공 쌍 (EHP)이 여기될 경우에는 Jsc와 Eff가 극대화되지만, 조사광 강도 또는 EHP가 더 높아질 경우에는 직렬저항의 증가와 함께 전류-전압 (I-V)의 이상인자 (ideality factor)가 커짐으로서 FF와 효율이 급격히 감소한 결과로 분석된다. 현재 전산모사를 통한 자세한 분석을 진행하고 있으며, 본 결과는 효율 극대화를 위한 최적 층구조 및 도핑 밀도 설계에 활용할 수 있을 것으로 판단된다.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.9-12
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• 2000

InP/lnGaAs heterojunciton phototransistors (HPTs) with transparent emitter contacts were fabricated and characterized. Indium Tin Oxide was RF sputtered for the emitter contacts. By comparison with InP/InGaAs HBTs, the dc characteristics of InP/lnGaAs HPTs demonstrated offset voltage due to ITO emitter contacts and similar common emitter current gain. The model parameters were extracted and a simple SPICE simulations were performed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.44.1-44.1
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• 2011

본 연구에서는 태양전지 설계를 위해 기존의 반도체소자 simulation에 사용되고 있는 Silvaco TCAD tool을 사용하여 p+ boron emitter의 특성분석 실험을 하였다. 변수로는 emitter의 농도와 접촉저항 이 두 가지 놓고 표면 재결합과 의 영향을 염두에 두고 실험을 하였다. 농도는 $1{\times}10^{17}\;cm^{-3}$에서 $2{\times}10^{22}\;cm^{-3}$까지 두었고, 각각의 농도에 해당되는 contact 저항을 설정하여 전기적 특성을 보았다. 실험 결과 두 가지 변수를 모두 입력하였을 때 처음에 Isc가 조금씩 올라가다가 $1{\times}10^8\;cm^{-3}$에서 가장 높았고 그 이후에는 표면 재결합이 커지면서 Isc가 계속 떨어졌다. 하지만 contact 저항으로 인해 가장 높은 효율은 $1{\times}10^9\;cm^{-3}$ 부근에서 보였다. 농도에 따라 표면 재결합과 contact 저항이 서로 반대로 변하기 때문에 emitter를 표면 재결합이 늘어남에도 불구하고 contact 저항으로 인해 비교적 고농도로 doping 해야만 했다. 하지만 우리가 준 contact 저항은 농도에 따라 생긴 저항으로 실제 전극의 contact 저항은 훨씬 더 클 것으로 예상되고 이로 인해 더 고농도의 doping이 필요하게 된다. 그렇게 된다면 표면의 재결합으로 인한 손실은 더 크게 되어 전체적으로 효율은 떨어진다. 우리는 이 손실을 보완하고 줄이기 위해 selective emitter 개념을 넣어 이에 대한 영향은 보았다. selective를 하지 않은 $1{\times}10^{19}\;cm^{-3}$의 doping 농도의 가장 높은 효율을 보인 기존의 emitter와 전극 부분을 제외한 표면은 $1{\times}10^{18}\;cm^{-3}$으로 하고 전극 부분의 emitter는 $2{\times}10^{20}\;cm^{-3}$으로 한 selective emitter를 비교해보았다. 이는 selective emitter가 기존 emitter에 비해 Isc와 Fill Factor로 인해 효율이 약 0.7% 정도 높았다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.268-272
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• 2007

A fully integrable InP/InGaAs HPT with an ITO emitter contact was first fabricated by employing a $SiO_2$ passivation layer. The electrical and the optical characteristics of the HPT with a passivation layer were measured and compared with those of the HPT without a passivation layer. The only noticeable difference was the increased emitter series resistance of the HPT with a passivation layer. AES analysis was performed to explain the reason of the increased emitter series resistance. Results show that PECVD $SiO_2$ deposition and annealing processes cause the diffusion of oxygen to the interface and the depletion of tin at the interface, which may be responsible for the increase of the series resistance.

• Current Optics and Photonics
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• v.3 no.5
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• pp.445-450
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• 2019

The influence of high-power laser diode (HPLD) emitter width on the device performance is investigated for 975-nm (In,Ga)(As,P)/(Al,Ga)As broad-area HPLDs, using self-consistent electro-thermal-optical simulation. To guarantee the simulation's accuracy, simulated results are matched with the measured results for a sample HPLD with fitting parameters. The influences of HPLD emitter width on temperature distribution, output power, and the beam product parameter (BPP) are analyzed for three different emitter widths of 50, 70, and $90{\mu}m$. It is found that a device with smaller emitter width exhibits both thermal rollover and thermal blooming at lower output power, but smaller BPP.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.229-232
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• 2000

InP/lnGaAs HPT's were fabricated by employing Indium Tin Oxide(ITO) transparent emitter contact. The device showed the current gaing 70 was obtained but the emitter series resistance was significantly increased. the electrical charateristics of the device were similar to HBT's. However Vceoff was shifted the positive direction. Such a shift ma be resulted from the formation of the shottky barrier rather than the ohmic contact between ITO and n+ InP emitter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.83-87
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• 2020

In this letter, we propose and analyze a new asymmetric structure that can be used for next-generation power semiconductor devices. We compare and analyze the electrical characteristics of the proposed device with respect to those of symmetric devices. The proposed device has a p-emitter on the right side of the cell. The peak electric field is reduced by the shielding effect caused by the p-emitter structure. Consequently, the breakdown voltage is increased. The proposed asymmetric structure has an approximately 100% higher Baliga's figure of merit (~94.22 MW/㎠) than the symmetric structure (~46.93 MW/㎠), and the breakdown voltage of the device increases by approximately 70%.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.121-124
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• 2008

This paper presents the fabrication and field emission of carbon nanotube field emitters for a micro mass spectrometer. The carbon nanotube is an adequate material as a field emitter since it has good characteristics. We have successfully fabricated a diode field emitter and a triode field emitter. Each field emitter has been constructed using several micromachining processes and a thermal CVD process. In the case of the diode field emitter, to increase the electric field, the carbon nanotubes are selectively grown on the patterned nickel catalyst layer. The electron current of the diode field emitter is 73.2 ${\mu}A$ when the anode voltage is 1100V. That of the triode field emitter is 3.4 pA when the anode voltage is 1000V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.10-12
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• 1996

AlGaAs/GaAs Heterojunotion Bipolar Transistors (HBTs) with various emitter areas were fabricated and the device size dependence on the current gain was examined. With the different emitter areas, the passivated devices having the same peripheral length were fabricated and measured. The measured base current density in the Gummel plots shows an ideality factor of nearly 2. It is found that as the emitter area becomes small, the base current density with the ideality factor of 2 increases linearly, and as the emitter perimeter/area ratio becomes large, the surface recombination current density component increases. The current gain performance in AlGaAs/GaAs HBTs is mainly determined by either the larger emitter area or the smaller ratio of the emitter perimeter to the emitter area. These results will be compared with experimental works for GaInP/GaAs HBTs