• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.768-771
• /
• 2006

Uniformity and performance characteristics of LTPS TFTs are important parameters for making advanced active-matrix displays. In this paper, we describe an SLS-based crystallization approach for producing orientation-controlled Si films with reduced concentrations of planar defects that stand to potentially deliver unprecedented levels of device uniformity and performance. Specifically, a 2-step process referred to as hybrid SLS has been developed that produces a variety of high-quality {100} surface-oriented Si films.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.6
• /
• pp.754-757
• /
• 1986

Boron monophosphide(100) was eitaxially grown on Si(100) substrate by thermal reaction of B2H6 and PH3 in hydrogen ambient. In an LPCVD system, the growth condition was studied as a function of gas mixture composition and temperature. For the growth temperature of 950\ulcorner in the constant flow rate (partial pressure) of B2H6, n-BP with c(2x2) surface structure was obtained in the PH3 partial pressure of 300-500 cc/min. On the other hand, for the growth temperature of 1080\ulcorner, p-BP with surface structure was observed for the PH3 partial pressure of 400-500cc/min.

• Nuclear Engineering and Technology
• /
• v.51 no.5
• /
• pp.1428-1435
• /
• 2019

The total ionizing dose (TID) and non ionizing energy loss (NIEL) effects of 100 MeV phosphorous ($P^{7+}$) and 80 MeV nitrogen ($N^{6+}$) ions on 200 GHz silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were examined in the total dose range from 1 to 100 Mrad(Si). The in-situ I-V characteristics like Gummel characteristics, excess base current (${\Delta}I_B$), net oxide trapped charge ($N_{OX}$), current gain ($h_{FE}$), avalanche multiplication (M-1), neutral base recombination (NBR) and output characteristics ($I_C-V_{CE}$) were analysed before and after irradiation. The significant degradation in device parameters was observed after $100MeV\;P^{7+}$ and $80MeV\;N^{6+}$ ion irradiation. The $100MeV\;P^{7+}$ ions create more damage in the SiGe HBT structure and in turn degrade the electrical characteristics of SiGe HBTs more when compared to $80MeV\;N^{6+}$. The SiGe HBTs irradiated up to 100 Mrad of total dose were annealed from $50^{\circ}C$ to $400^{\circ}C$ in different steps for 30 min duration in order to study the recovery of electrical characteristics. The recovery factors (RFs) are employed to analyse the contribution of room temperature and isochronal annealing in total recovery.

• Journal of the Mineralogical Society of Korea
• /
• v.28 no.4
• /
• pp.299-308
• /
• 2015

The six natural zeolites collected in Pohang area, Kyungsangbuk-do, Korea, were characterized by XRD, XRF, DTA, TGA, and CEC analysis. The primary species of these zeolite are modenite, albite, and quarts in Kuryongpo-A (Ku-A), Kuryongpo-B (Ku-B), Kuryongpo-C (Ku-C), Donghae-A (Dh-A), Donghae-B (Dh-B), and Donghae-C (Dh-C) samples. The XRF analysis showed that the six zeolites contain Si, Al, Na, K, Mg, Ca, and Fe. Cation exchange capacity of Kuryongpo-C (Ku-C) zeolite was the highest compared to other zeolites. The capabilities of removing heavy metal ions such as $Pb^{2+}$, $Cd^{2+}$ and $Cu^{2+}$ were compared. The effect of reaction time in removing heavy metal ions was studied. The experimental results showed that the efficiency of removal was low for $Pb^{2+}$, $Cd^{2+}$ and $Cu^{2+}$ ions. These may be caused by the low content of zeolite in the six natural zeolites. This indicates that the adsorption capacity roughly tends to depend on the zeoite contents, ie., the grade of zeolite ore.

• Journal of Korea Foundry Society
• /
• v.38 no.2
• /
• pp.32-40
• /
• 2018

Changes in the microstructures and mechanical properties of an AC2B alloy through solution heat treatment were investigated using recycled AC2B cutting chips as raw material. The as-cast microstructure of the AC2B alloy comprised ${\alpha}$-Al, $Al_2Cu$, and coarse needle-shaped phases considered to be eutectic Si and an Al-Fe-Si based intermetallic compound. After solution heat treatments at $505^{\circ}C$ for 1 h and 6 h, the samples showed complete dissolution of $Al_2Cu$ and relatively fine distribution of intermetallic compounds. Hardness test results showed that the hardness rapidly increased after the solution heat treatment for 1 h by solid solution hardening, and the increase of hardness exhibited a plateau from 1 h to 6 h. The results of the hardness and tensile tests showed that there was no visible difference in the effect of 1 h and 6 h solid solution treatment.

• Korean Journal of Materials Research
• /
• v.21 no.1
• /
• pp.1-7
• /
• 2011

Methods of producing hydrogen include steam reforming, electrochemical decomposition of water, and the SI process. Among these methods, the Sulfur iodine process is one of the most promising processes for hydrogen production. The thermochemical sulfur-iodine (SI) process uses heat from a high-temperature-gas nuclear reactor to produce $H_2$ gas; this process is known for its production of clean energy as it does not emit $CO_2$ from water. But the SI-process takes place in an extremely corrosive environment for the materials. To endure SI environments, the materials for the SI environment will have to have strong corrosion resistance. This work studies the corrosion resistances of the Fe-Si, Ni-Ti and Ni Alloys, which are tested in SI-process environments. Among the SI-process environments, the conditions of boiling sulfuric acid and decomposed sulfuric acid are selected in this study. Before testing in boiling sulfuric acid environments, the specimens of Fe-4.5Si, Fe-6Si, Ni-4.5Si, Ni-Ti-Si-Nb and Ni-Ti-Si-Nb-B are previously given heat treatment at $1000^{\circ}C$ for 48 hrs. The reason for this heat treatment is that those specimens have a passive film on the surface. The specimens are immersed for 3~14 days in 98wt% boiling sulfuric acid. Corrosion rates are measured by using the weight change after immersion. The corrosion rates of the Fe-6Si and Ni-Ti-Si-Nb-B are found to decrease as the time passes. The corrosion rates of Fe-6si and Ni-Ti-Si-Nb-B are measured at 0.056 mm/yr and 0.16 mm/yr, respectively. Hastelloy-X, Alloy 617, Alloy 800H and Haynes 230 are tested in the decomposed sulfuric acid for one day. Alloy 800H was found to show the best corrosion resistance among the materials. The corrosion rate of Alloy 800H is measured at -0.35 mm/yr. In these results, the corrosion resistance of materials depends on the stability of the oxide film formed on the surface. After testing in boiling sulfuric acid and in decomposed sulfuric acid environments, the surfaces and compositions of specimens are analyzed by SEM and EDX.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.11
• /
• pp.910-917
• /
• 2009

We have designed a new structures of Junction Field Effect Transistor(JFET) using SILVACO simulation to improve electrical properties and process reliability. The device structure and process conditions of Si control JFET(Si JFET) were determined to set cut off voltage and drain current(at Vg=0 V) to -0.46 V and $300\;{\mu}A$, respectively. Among many design parameters influencing the performance of the device, the drive-in time of p-type gate is presented most predominant effects. Therefore we newly designed SiGe JFET, in which SiGe layers were placed above and underneath of Si-channel. The presence of SiGe layer could lessen Boron into the n-type Si channel, so that it would be able to enhance the structural consistency of p-n-p junction. The influence of SiGe layer could be explained in conjunction with boron diffusion and corresponding I-V characteristics in comparison with Si-control JFET.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.25-28
• /
• 2001

The objectives of this paper are to demonstrate the electrical degradation phenomena with Si atom's behaviors in the grainboundary of semiconducting ZnO ceramics. The ZnO ceramic devices used in this investigation were fabricated by standard ceramic techniques. Especially, $SiO_2$ were added to analyze the degradation characteristics with Si and sintered in oxygen ambient at $1300^{\circ}C$. The conditions of DC degradation test were $115{\pm}2^{\circ}C$ for 13h. Using XRD and SEM, the phase and microstructure of samples were analyzed respectively. E-J analysis was used to determine $\alpha$. Frequency analysis was accomplished to understand $R_g$ and $R_b$ at the equivalent circuit. Electrical stability improved as the amount of $SiO_2$ addition increased. This results were explain by the quantitative analysis and the line scanning method of EPMA.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.104.1-104.1
• /
• 2011

가볍고, 유연성(flexibility)을 갖는 박막(thin film)형 플랙서블 태양전지(flexible solar cell)는 상황에 따른 형태의 변형이 가능하여, 휴대가 간편하고, 기존 혹은 신규 구조물의 지붕(rooftop)등에 설치가 용이하여, 차세대 성장 동력 분야에서 각광받고 있다. 그러나 아직까지 플랙서블 태양전지는 제작시 열에 의한 기판의 변형, 기판 이송시 너울 현상, 대면적 패터닝(patterning) 기술 등 많은 어려움 등으로 웨이퍼나 글라스 기판에 제조된 태양전지 대비 낮은 광전환 효율을 갖는다. 따라서 본 연구에서는 플랙서플 태양전지 성능개선을 위해 3.5세대급 ($450{\times}450cm^2$) 스퍼터(sputter), 금속유기 화학기상장치 (MOCVD), 플라즈마 화학기상장치 (PECVD), 레이저 가공장치 (Laser scriber)를 이용하여 a-Si:H/a-SiGe:H 이중접합(tandem)을 갖는 태양전지를 제작하였고, 광 변환효율 특성을 평가하였다. 전도도(conductivity), 라만(Raman)분광 및 UV/Visible 분광 분석을 통하여 박막의 전기적, 구조적, 광학적 물성을 평가하여 단위박막의 물성을 최적화 했다. 또한 제작된 태양전지는 쏠라 시뮬레이터 (Solar Simulator)를 이용하여 성능 평가를 수행하였고, 상/하부층의 전류 정합 (current matching)을 위해 외부양자효율 (external quantum efficiency) 분석을 수행하였다. 제작된 이중접합 접이식 태양전지로 소면적($0.25cm^2$)에서 8.7%, 대면적($360cm^2$ 이상) 8.0% 이상의 효율을 확보하였으며, 성능 개선을 위해 대면적 패턴 기술 향상 및 공정 기술 개선을 수행 중이다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.4
• /
• pp.176-181
• /
• 2003

Rapid densification of a SiC powder with additive 0.5 wt% $B_4$C was conducted by spark plasma sintering (SPS). The unique features of the process are the possibilities of using very fast heating rate and short holding time to obtain fully dense materials. The heating rate and applied pressure were kept to be $100^{\circ}C$/min and 40 MPa, while sintering temperature and soaking time varied to 1800, 1850, 1900 and $1950^{\circ}C$ and 10, 20 and 30 min, respectively. All of the SPS-sintered specimens at $1950^{\circ}C$ reached near-theoretical density. The XRD found that 3C-to-6H transformation at $1850^{\circ}C$. The microstructures of the rapidly densified SiC ceramics consisted of duplex microstructure with ultrafine equiaxed grains under 2 $\mu\textrm{m}$ and elongated grains of 0.5∼2 $\mu\textrm{m}$ wide, length 3∼10 $\mu\textrm{m}$. The biaxial strength increased with the increase of sintering time. Strength of 392.7 MPa was obtained with the fully densified specimen sintered at $1950^{\circ}C$ for 30 min, in agreement with the general tendency that strength increases with decreases pore. On the other hand, the fracture toughness shows the value of 2.17∼2.34 MPa$.$$m^{1/2}$ which might be due to the transgranular fracture mode.