• Journal of IKEEE
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• v.27 no.4
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• pp.556-560
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• 2023

In this study, the impact of Nitrogen implantation process on deep-level defects and lifetime in 4H-SiC Epi surfaces was comparatively analyzed. Deep Level Transient Spectroscopy (DLTS) and Time Resolved Photoluminescence (TR-PL) were employed to measure deep-level defects and carrier lifetime. As-grown Schottky Barrier Diodes (SBDs) exhibited energy levels at 0.16 eV, 0.67 eV, and 1.54 eV, while for implantation SBD, defects at 0.15 eV were observed. This indicates a reduction in defects associated with energy levels Z_1/2 and EH_6/7, known as lifetime killers, as impurities from nitrogen implantation replace titanium and carbon vacancies.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1953-1955
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• 1999

The effects of the local lifetime control on the characteristics of IGBT are investigated using the 2-dimensional device simulator, MEDICI. Many lumped resistive turn-off simulations are carried out to analyze the effects of the minority carrier lifetime, the width, and the position of the region with a reduced local minority carrier lifetime. As a result of these simulations, it is concluded that the on state voltage drop$(V_{CE,SAT})$ is only slightly increased while the switching behavior is greatly improved if the low lifetime region is properly set. And these results are compared with IGBTs having uniform lifetime.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.3
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• pp.216-221
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• 2006

Lifetime control technique by proton implantation has become an useful tool for production of modern power devices. In this work, punch-through type diodes were irradiated with protons for the high speed power diode fabrication. Proton irradiation which was capable of controlling carrier's lifetime locally was carried out at the various energy and dose conditions. Characterization of the device was performed by current-voltage, capacitance-voltage and reverse recovery time measurement. We obtained enhanced reverse recovery time characteristics which was about $45\;\%$ of original device reverse recovery time and about $73\;\%$ of electron irradiated device reverse recovery time. The measurement results showed that proton irradiation technique was able to effectively reduce minority carrier lifetime without degrading the other characteristics.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.429-429
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• 2012

To investigate the gettering effect of B-doped n-type monocrystalline silicon wafer, we made the p-n junction by diffusing boron into n-type monocrystalline Si substrate and then oxidized the boron doped n-type monocrystalline silicon wafer by in-situ wet and dry oxidation. After oxidation, the minority carrier lifetime was measured by using microwave photoconductance and the sheet resistance by 4-point probe, respectively. The junction depth was analyzed by Secondary Ion Mass Spectrometry (SIMS). Boron diffusion reduced the metal impurities in the bulk of silicon wafer and increased the minority carrier lifetime. In the case of wet oxidation, the sheet resistance value of ${\sim}46{\Omega}/{\Box}$ was obtained at $900^{\circ}C$, depostion time 50 min, and drive-in time 10 min. Uniformity was ~7% at $925^{\circ}C$, deposition time 30 min, and drive-in time 10 min. Finally, the minority carrier lifetime was shown to be increased from $3.3{\mu}s$ for bare wafer to $21.6{\mu}s$ for $900^{\circ}C$, deposition 40 min, and drive-in 10 min condition. In the case of dry oxidation, for the condition of 50 min deposition, 10 min drive-in, and O2 flow of 2000 SCCM, the minority carrier lifetime of 16.3us, the sheet resistance of ${\sim}48{\Omega}/{\Box}$, and uniformity of 2% were measured.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.732-736
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• 2009

Protons are irradiated into SOl wafers under total dose of 100 krad, 500 krad, 1 Mrad and 2 Mrad to analyze the irradiation effect. The electrical properties are analyzed by pseudo MOSFET technology after proton irradiation. The wafers are annealed to stabilize generated defects in a nitrogen atmosphere at $300^{\circ}C$ for 1 hour because proton irradiation induces a lot of unstable defects in the surface silicon film. Both negative and positive turn-on voltages are shifted to negative direction after the irradiation. The more proton total dose, the more turn on voltage shifts. It means that positive oxide trap charge is generated in the buried oxide(BOX). The minority carrier lifetime which is analyzed by the drain current transient characteristics decreases with the increase of proton total dose. The proton irradiation makes crystal defects in the silicon film, and consequently, the crystal defects reduce the carrier lifetime and mobility. As these results, it can be concluded that pseudo MOSFET is a useful technology for the analysis of irradiated SOI wafer.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.152-152
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• 2010

이종접합 태양전지에서 Intrinsic a-Si:H의 역할은 상당히 중요하다. Passivation 효과와 높은 Voc에 이르는 핵심적인 Layer이다. 본 연구는 Intrinsic a-Si:H Layer의 증착조건을 가변하여 최적의 Passivation 효과를 얻는데 목적이 있다. 웨이퍼는 n-Type $500\;{\mu}m$두께에를 사용하였다. Intrinsic a-Si:H Layer는 $SiH_4$ 가스와 $H_2$ 가스를 혼합하여 증착하게 되는데 혼합비는 1:5로 고정하였다. 증착두께는 이종접합 태양전지에서 필요한 5nm로 고정하였으며 증착장비는 PECVD를 이용하였다. PECVD는 VHF(60MHz)를 이용하였고 증착온도는 $200^{\circ}C$로 고정하여 진행하였다. 가변내용은 전극거리와 파워, 압력이다. 전극거리는 20mm에서 80mm까지 가변하였고 압력은 100mTorr에서 500mTorr까지 가변하였다. 파워는 플라즈마의 방정특성을 알아본 후 최소파워를 이용하여 증착하였다. 이는 증착 시 플라즈마에 의한 박막 손상을 최소화하기 위함이다. 측정은 QSSPC 방식으로 Carrier Lifetime과 Implied Voc를 측정하였으며 두께는 Ellipsometry를 이용하여 측정하였다. 전극거리 60mm에서 증착압력은 400mTorr이고 파워는 $14mW/cm^2$에서 가장 높은 Carrier Lifetime 과 Implied Voc를 나타내었다. Carrier Lifetime은 2.2ms이고 Implied Voc는 709mV를 달성 하였다. Carrier Lifetime이 높으면 Surface Recombination이 낮다는 의미이며 이는 고효율 이종접합 태양전지 제작에 있어서 직렬저항을 줄일 수 있는 필수적인 요소이다. Implied Voc는 이종접합 태양전지의 Voc에 직결된 인자로 이종접합 태양전지의 Voc를 예상할 수 있는 중요한 요소이다.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.107-112
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• 2017

The BCBJ (Back Contact and Back Junction) or back-lit solar cell design eliminates shading loss by placing the pn junction and metal electrode contacts all on one side that faces away from the sun. However, as the electron-hole generation sites now are located very far from the pn junction, loss by minority-carrier recombination can be a significant issue. Utilizing Medici, a 2-dimensional semiconductor device simulation tool, the interdependency between the substrate thickness and the minority-carrier recombination lifetime was studied in terms of how these factors affect the solar cell power output. Qualitatively speaking, the results indicate that a very high quality substrate with a long recombination lifetime is needed to maintain the maximum power generation. The quantitative value of the recombination lifetime of minority-carriers, i.e., electrons in p-type substrates, required in the BCBJ cell is about one order of magnitude longer than that in the front-lit cell, i.e., $5{\times}10^{-4}sec$ vs. $5{\times}10^{-5}sec$. Regardless of substrate thickness up to $150{\mu}m$, the power output in the BCBJ cell stays at nearly the maximum value of about $1.8{\times}10^{-2}W{\cdot}cm^{-2}$, or $18mW{\cdot}cm^{-2}$, as long as the recombination lifetime is $5{\times}10^{-4}s$ or longer. The output power, however, declines steeply to as low as $10mW{\cdot}cm^{-2}$ when the recombination lifetime becomes significantly shorter than $5{\times}10^{-4}sec$. Substrate thinning is found to be not as effective as in the front-lit case in stemming the decline in the output power. In view of these results, for BCBJ applications, the substrate needs to be only mono-crystalline Si of very high quality. This bars the use of poly-crystalline Si, which is gaining wider acceptance in standard front-lit solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.252-253
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• 2005

The effects of As addition in amorphous selenium (a-Se) films on the carrier mobilities and the recombination lifetime have been studied using the moving photo-carrier grating (MPG) measurements. The electron and hole mobility, and recombination lifetime of a-Se films with arsenic (As) additions up to 1% have been obtained. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density from shallow traps.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.4
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• pp.30-35
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• 1983

Numerical calculations have been made about the phase differences of the short circuit current in a solar cell according to the variation of the modulation frequency. The phase differences in short circuit current of the solar cell exposed to the modulated light source is measured experimentally. From the above two results, the minority carrier lifetime has been determined. Also, minority carrier lifetime has been determined from the observed photo-induced open circuit voltage decay wave form that follows termination of the excitation.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.243-246
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• 1999

We studied the MOSFET characteristics and the hot-carrier reliability with the sidewall spacer composition and the post gate oxidation thickness in 0.20${\mu}{\textrm}{m}$ gate length transistor. The MOSFET with NO(Nitride＋Oxide) sidewall spacer exhibits the large degradation of hot-carrier lifetime because there is no buffering oxide against nitride stress. When the post gate oxidation is skipped, the hot-carrier lifetime is improved, but GIDL (Gate Induced Drain Leakage) current is also increased.