• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권3호
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• pp.270-278
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• 2000

This study was conducted to compare the vein graft with the nerve graft, and evaluated the availability of the vein graft on the reconstruction of the inferior alveolar nerve defect. The experimental animals were 12 rabbits weighing $1.5{\sim}2.0kg$, divided into 3 groups : sham operation group, vein conduit group and nerve graft group. All nerves were excised and histomorphometric analysis was performed at 2, 4, 6, 12, 16 weeks after operation. The obtained results were as follows. 1. Histologic examination revealed the regenerated nerve fibers within the lumen of the vein graft and nerve graft at 6 weeks after repair. 2. Axon diameter was significantly larger in nerve graft group(p<0.05) than in vein graft group at 6weeks, and larger in nerve graft group than in vein graft group at 16weeks. 3. Axon density was higher in the vein graft group at 16 weeks. 4. The myelin of the regenerated nerve fibers in distal segment of the vein graft group was thick, approaching the proximal segment at 16weeks. This means remyelination in distal segment in the vein graft group. These results suggested that autogenous vein graft may be used as an alternative to autogenous nerve graft.

• 전자공학회논문지A
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• 제29A권1호
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• pp.33-40
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• 1992

4인치(100) 실리콘 기판상에 센서용 다이아프램을 제조할 때 생기는 식각 현상들을 관찰하고 분석하였다. 115$^{\circ}C$의 "F etch' 용액을 사용하여 300$\mu$ 이상의 깊은 식각을 행하였을 때 식각 표면에 발생하느 식각 결함은 hillock, 반응 생성물, 그리고 횐색 잔유물로 구분될 수 있었따. 특히 hillock의 경우 식각 표면에 부착된 반응 생성물의 밀도나 크기에 관계하여 |111|면들로 이루어질는 피라밋 구조나 사다리꼴 육면체등의 형태를 취함이 확인되었다. 또한 용해된 실리콘의 국부적인 과잉 포활 발생하는 흰색 잔유물의 IR 흡수 스펙트럼을 조사한 결과, Si-N-O 성분에 미량의 h와 C가 포함된 것임을 알 수 있었다. 아울러 식각면을 식각용액에 대해 아래쪽, 위쪽, 그리고 측면을 향하도록 놓았을때 식각 결함의 존재 확률과 분포 그리고 식각율의 분포를 비교한 결과 식각율의 균일성면에서는 하측방향의 자세가, 식각결함의 제거에 있어서는 측면방향의 자세가, 식각결함의 제거에 있어서는 측면방향의 자세가 유리하게 나타났으며 이를 반응조내의 흐름 패턴을 이용하여 해석하였다.

• 전자공학회논문지A
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• 제31A권12호
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• pp.80-90
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• 1994

To develop VLSI of higher packing density with 0.5.mu.m gate length of less, semiconductor devices require shallow junction with higher doping concentration. the most common method to form the shallow junction is ion implantation, but in order to remove the implantation induced defect and activate the implanted impurities electrically, ion-implanted Si should be annealed at high temperature. In this annealing, impurities are diffused out and redistributed, creating deep PN junction. These make it more difficult to form the shallow junction. Accordingly, to miimize impurity redistribution, the thermal-budget should be kept minimum, that is. RTA needs to be used. This paper reports results of the diffusion characteristics of PSG film by varying Phosphorus weitht %/ Times and temperatures of RTA. From the SIMS.ASR.4-point probe analysis, it was found that low sheet resistance below 100 .OMEGA./ㅁand shallow junction depths below 0.2.mu.m can be obtained and the surface concentrations are measured by SIMS analysis was shown to range from 2.5*10$^{17}$ aroms/cm$^{3}$~3*10$^{20}$ aroms/cm$^{3}$. By depending on the RTA process of PSG film on Si, LDD-structured nMOSFET was fabricated. The junction depths andthe concentration of n-region were about 0.06.mu.m. 2.5*10$^{17}$ atom/cm$^{-3}$ , 4*10$^{17}$ atoms/cm$^{-3}$ and 8*10$^{17}$ atoms/cm$^{3}$, respectively. As for the electrical characteristics of nMOS with phosphorus junction for n- region formed by RTA, it was found that the characteristics of device were improved. It was shown that the results were mainly due to the reduction of electric field which decreases hot carriers.

• 센서학회지
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• 제6권2호
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• pp.163-171
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• 1997

CSVT(close spaced vapor transport)증착시스템으로 태양전지의 창재에 적합한 CdS박막을 기판온도에 따라 증착하였으며, 실온에서 증착된 CdS박막을 온도를 변화시켜 가면서 열처리하였다. 증착 및 열처리후의 CdS박막의 구조적, 전기적 및 광학적 특성을 조사하였다. 증착조건에 무관하게 CdS박막들은 육방정계구조로 (002)면으로 기판에 수직으로 성장함을 확인하였다. 기판온도가 $25^{\circ}C$에서 $300^{\circ}C$까지 증가함에 따라 비저항은 $60{\Omega}cm$로 부터 $2{\times}10^{4}{\Omega}cm$로 단순증가하였으며 기판온도 $25^{\circ}C$에서 가시광영역에서의 광투과도가 80%정도로 가장 높았다. 열처리온도가 증가함에 따라 막내의 결정결함의 증가에 따라 비저항은 현저하게 증가하였으며 광투과도는 현저하게 감소하였다.

• 센서학회지
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• 제29권4호
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• pp.266-269
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• 2020

In this study, we investigated the effect of a sulfur passivation (S-passivation) process step on the electrical properties of surface-channel In_0.7Ga_0.3As quantum-well (QW) metal-oxide-semiconductor field-effect transistors (MOSFETs) with S/D regrowth contacts. We fabricated long-channel In_0.7Ga_0.3As QW MOSFETs with and without (NH₄)₂S treatment and then deposited 1/4 nm of Al₂O₃/HfO₂ through atomic layer deposition. The devices with S-passivation exhibited lower values of subthreshold swing (74 mV/decade) and drain-induced barrier lowering (19 mV/V) than the devices without S-passivation. A conductance method was applied, and a low value of interface trap density D_it (2.83×10¹² cm^-2eV^-1) was obtained for the devices with S-passivation. Based on these results, interface traps between InGaAs and high-κ are other defect sources that need to be considered in future studies to improve III-V microsensor sensing platforms.

• Journal of Welding and Joining
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• 제15권3호
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• pp.88-98
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• 1997

Welding defects, such as porosity and spike, have sometimes occurred in deep penetration electron beam welds. These defects are known to be one of the serious problem in electron beam welds. So, effects of active parameters ($a_b$) on bead shape and occurrence of defects in electron beam welds of heavy section 9%Ni steel plates were investigated. Partial penetration welding in flat position, and deep penetration welding of 10 ~ 28mm depth were investigated in this study. It is desirable to select low accelerating voltage and above the surface focus position $a_b$$\geq$1.2 at which a wine-cup shaped bead is obtained to avoid the welding defects such as spike and root porosity. When the accelerating voltage of electron beam was low (90kV), active parameter ($a_b$) did not influence on the bead width, penetration depth and weld defects significantly. However, in case of high voltage ($\geq$120kV), active parameter ($a_b$) was sensitively associated with penetraton depth and weld defects, i.e. when the active parameter (($a_b$) was in the range of 0.6 to 1.0, the depth of penetration was always over the target (23mm), while the depth of penetration was dramatically decreased with further increase of active parameter ($a_b$). The weld defects were decreased with the increase of active parameter $a_b$ resulting in the decrease of energy density of the focused beam in the root part of fusion zone.

• 한국세라믹학회지
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• 제51권3호
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• pp.197-200
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• 2014

We investigated the influence of blistering on $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks passivation layers. $Al_2O_3$ film provides outstanding Si surface passivation quality. $Al_2O_3$ film as the rear passivation layer of a p-type Si solar cell is usually stacked with a capping layer, such as $SiO_2$, SiNx, and SiON films. These capping layers protect the thin $Al_2O_3$ layer from an Al electrode during the annealing process. We compared $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks through surface morphology and minority carrier lifetime after annealing processes at $450^{\circ}C$ and $850^{\circ}C$. As a result, the $Al_2O_3$/SiON stacks were observed to produce less blister phenomenon than $Al_2O_3$/SiNx:H stacks. This can be explained by the differences in the H species content. In the process of depositing SiNx film, the rich H species in $NH_3$ source are diffused to the $Al_2O_3$ film. On the other hand, less hydrogen diffusion occurs in SiON film as it contains less H species than SiNx film. This blister phenomenon leads to an increase insurface defect density. Consequently, the $Al_2O_3$/SiON stacks had a higher minority carrier lifetime than the $Al_2O_3$/SiNx:H stacks.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.233-244
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• 2004

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_2O_3$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193nm) excimer laser. The epilayers of ZnO were achieved on sapphire ($Al_2O_3$)substrate at a temperature of $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}10^{16}\;cm^{-3}$ and $299\;{\textrm}cm^2/V.s$ at 293K. respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;3.3973\;eV\;-\;(2.69{\times}10^{-4}\;eV/K)T^2/(T+463K)$. After the as-grown ZnO epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO atmospheres has been investigated by the photoluminescence(PL) at 10K. The native defects of $V_{zn},\;Vo,\;Zn_{int},\;and\;O_{int}$ obtained by PL measurements were classified as a donors or acceptors type. In addition, we concluded that the heat-treatment in the oxygen atmosphere converted ZnO thin films to an optical p-type. Also, we confirmed that vacuum in $ZnO/Al_2O_3$ did not form the native defects because vacuum in ZnO thin films existed in the form of stable bonds.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.386-391
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• 2003

Sing1e crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}\;s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.86\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;155K)$. After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ thin films has been investigated by PL at 10 K. The native defects of $V_{Cd}$, $V_{Se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or accepters. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also, we confirmed that Al in $CuAlSe_2/GaAs$ did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.467-475
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• 2004

ZnO epilayer were synthesized by the pulsed laser deposition(PLD) process on $Al_2$ $O_3$substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193 nm) excimer laser. The epilayers of ZnO were achieved on sapphire(A $l_2$ $O_3$) substrate at a temperature of 400 $^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are 8.27${\times}$$10^{16}$$cm^{-3}$ and 299 $\textrm{cm}^2$/Vㆍs at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_{g}$(T)= 3.3973 eV - (2.69 ${\times}$ 10$_{-4}$ eV/K) $T^2$(T＋463k). After the as-grown ZnO epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO atmospheres has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Zn}$ , $V_{o}$ , Z $n_{int}$, and $O_{int}$ obtained by PL measurements were classified as a donors or accepters type. In addition, we concluded that the heat-treatment in the oxygen atmosphere converted ZnO thin films to an optical p-type. Also, we confirmed that vacuum in ZnO/A $l_2$ $O_3$did not form the native defects because vacuum in ZnO thin films existed in the form of stable bonds.s.s.s.