• 한국재료학회지
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• 제14권1호
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• pp.9-12
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• 2004

Metallic impurities, such as Fe, Cu, and Au, become generation and recombination centers for minority carriers when combined with oxide precipitates or silicon self-interstitial clusters. As these centers may cause leakage and discharge in silicon devices, their prevention through gettering of the metallic impurities is an important issue. In this article, key aspects of intrinsic gettering, such as oxygen control, wafer cleaning, device area denudation, and bulk oxygen precipitation are discussed, and a practical method of implementing intrinsic gettering is outlined.

• 대한화학회지
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• 제67권5호
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• pp.333-338
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• 2023

In this study, the H₂O reaction with SiO clusters was investigated using ab initio Monte Carlo simulations and density functional theory calculations. Three chemistry models, PBE1/DGDZVP (Model 1), PBE1/DGDZVP (Si atom), and aug-cc-pVDZ (O and H atoms), (Model 2) and PBE1/aug-cc-pVDZ (Model 3), were used. The average bond lengths, as well as the relative and reaction energies, were calculated using Models 1, 2, and 3. The average bond lengths of Si-O and O-H are 1.67-1.75 Å and 0.96-0.97 Å, respectively, using Models 1, 2, and 3. The most stable structures were formed by the H transfer from an H₂O molecule except for Si₃O₃-H₂O-1 cluster. The Si₃O₃ cluster with H₂O exhibited the lowest reaction energy. In addition, the Bader charge distributions of the Si_nO_n and (SiO)_n-H₂O clusters with n = 1-7 were calculated using Model 1. We determined that the reaction sites between H₂O and the SiO clusters possessed the highest fraction of electrons.

• 대한화학회지
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• 제60권4호
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• pp.239-244
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• 2016

안정된 구조로 알려진 산화구리 클러스터(Cu_nO_n, n = 1 - 8)를 이용하여 구리 원자를 규소 원자로 치환하여 Cu_mSiO_m+1 (m = 0 - 7)의 안정된 구조를 최적화하였다. B3LYP/LANL2DZ의 이론수준에서 계산하였으며 중성과 하전된 안정된 구조를 계산하였다. 구리원자를 규소 원자로 치환으로 인한 구조적 변화를 위해 결합길이, 결합각, 그리고 Mulliken 전하를 계산하였다. 클러스터의 상대적 안정성을 구하기 위해 second differences in energy를 계산하였고 전기적 특성을 연구하기 위해 이온화 에너지와 전자친화도 계산을 수행하였다.

• 한국결정성장학회지
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• 제11권3호
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• pp.89-95
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• 2001

규소 결정의 용융 온도 근처인 $1350^{\circ}C$에서 Ar과 $O_{2}$gas를 이용하여 규소 wafer의 열처리시 vacancy ty[e 결함의 거동에 대해 알아보았다. 이 열처리에서는 wafer의 표면보다 wafer내부에서 결함의 용해속도가 매우 높음을 확인하였다. 이는 $1350^{\circ}C$에서는 규소내의 평형산소농도가 대부분의 CZ silicon에서의 산소농도보다 높아 산소의 understaturation현상과 silicon interstitial농도의 영향에 기인된 것으로 예상된다. 열처리 분위기의 영향을 알아보기 위하여 Ar과 $O_{2}$ 분위기에서 열처리한 결과 vacancy type 결함의 용해속도는 wafer의 내부에서는 차이가 없었고, wafer의 표면에서는 Ar이 $O_{2}$의 경우보다 결함의 용해속도가 높았다. $O_{2}$의 경우에는 표면산화막 성장시 유입된 silicon interstitial의 농도가 높아 결함의 용해속도가 떨어지는 것으로 판단된다. 이는 기존 연구에서 예상된 silicon interstitial이 vacancy cluster로 알려진 결정결함의 제거에 기여한다는 예상과는 상반된다. 본 연구의 결과 silicon interstitial의 존재는 void외부 산화막의 용해속도를 늦추어 결함 용해속도를 떨어뜨리는 것으로 예상된다.

• 한국재료학회지
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• 제21권5호
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• pp.273-276
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• 2011

Ultraviolet (UV) light emitting diodes (LEDs) were grown on a patterned n-type GaN substrate (PNS) with 200 nm silicon-di-oxide (SiO2) nano pattern diameter to improve the light output efficiency of the diodes. Wet etched self assembled indium tin oxide (ITO) nano clusters serve as a dry etching mask for converting the SiO2 layer grown on the n-GaN template into SiO2 nano patterns by inductively coupled plasma etching. PNS is obtained by n-GaN regrowth on the SiO2 nano patterns and UV-LEDs were fabricated using PNS as a template. Two UV-LEDs, a reference LED without PNS and a 200 nm PNS UV-LEDs were fabricated. Scanning Electron microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Photoluminescence (PL) and Light output intensity- Input current- Voltage (L-I-V) characteristics were used to evaluate the ITO-$SiO_2$ nanopattern surface morphology, threading dislocation propagation, PNS crystalline property, PNS optical property and UVLED device performance respectively. The light out put intensity was enhanced by 1.6times@100mA for the LED grown on PNS compared to the reference LED with out PNS.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.68.1-68.1
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• 2012

The best part of graphene is - charge-carriers in it are mass less particles which move in near relativistic speeds. Comparing to other materials, electrons in graphene travel much faster - at speeds of $10^8cm/s$. A graphene sheet is pure enough to ensure that electrons can travel a fair distance before colliding. Electronic devices few nanometers long that would be able to transmit charge at breath taking speeds for a fraction of power compared to present day CMOS transistors. Many researches try to check a possibility to make it a perfect replacement for silicon based devices. Graphene has shown high potential to be used as interconnects in the field of high frequency electrical devices. With all those advantages of graphene, we demonstrate characteristics of electrical and optical properties of graphene such as the effect of graphene geometry on the microwave properties using the measurements of S-parameter in range of 500 MHz - 40 GHz at room temperature condition. We confirm that impedance and resistance decrease with increasing the number of graphene layer and w/L ratio. This result shows proper geometry of graphene to be used as high frequency interconnects. This study also presents the optical properties of graphene oxide (GO), which were deposited in different substrate, or influenced by oxygen plasma, were confirmed using different characterization techniques. 4-6 layers of the polycrystalline GO layers, which were confirmed by High resolution transmission electron microscopy (HRTEM) and electron diffraction analysis, were shown short range order of crystallization by the substrate as well as interlayer effect with an increase in interplanar spacing, which can be attributed to the presence of oxygen functional groups on its layers. X-ray photoelectron Spectroscopy (XPS) and Raman spectroscopy confirms the presence of the $sp^2$ and $sp^3$ hybridization due to the disordered crystal structures of the carbon atoms results from oxidation, and Fourier Transform Infrared spectroscopy (FTIR) and XPS analysis shows the changes in oxygen functional groups with nature of substrate. Moreover, the photoluminescent (PL) peak emission wavelength varies with substrate and the broad energy level distribution produces excitation dependent PL emission in a broad wavelength ranging from 400 to 650 nm. The structural and optical properties of oxygen plasma treated GO films for possible optoelectronic applications were also investigated using various characterization techniques. HRTEM and electron diffraction analysis confirmed that the oxygen plasma treatment results short range order crystallization in GO films with an increase in interplanar spacing, which can be attributed to the presence of oxygen functional groups. In addition, Electron energy loss spectroscopy (EELS) and Raman spectroscopy confirms the presence of the $sp^2$ and $sp^3$ hybridization due to the disordered crystal structures of the carbon atoms results from oxidation and XPS analysis shows that epoxy pairs convert to more stable C=O and O-C=O groups with oxygen plasma treatment. The broad energy level distribution resulting from the broad size distribution of the $sp^2$ clusters produces excitation dependent PL emission in a broad wavelength range from 400 to 650 nm. Our results suggest that substrate influenced, or oxygen treatment GO has higher potential for future optoelectronic devices by its various optical properties and visible PL emission.