• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.1044-1055
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• 1994

The preparation of ZrC/SiC mixed powders from $ZrSiO_4/C$ and $ZrSiO_4/Al/C$ systems was attempted in the temperature range below $1600^{\circ}C$ under Ar or $Ar/H_2$ gas flow(100-500ml/min). The formation mechanism and kinetics of ZrC/SiC were suggested and the resultant powders were characterized. In $ZrSiO_4/C$ system, ZrC and SiC were formed by competitive reaction of $ZrO_2(s)$ and SiO(g) with carbon at temperature higher than $1400^{\circ}C$. The apparent activation energy for the formation of ZrC was approximately 18.5kcal/mol($1400-1600^{\circ}C$). In $ZrSiO_4/Al/C$ system, ZrC was formed by reaction of ZrO(g) with Al(l, g) and carbon at temperature higher than $1200^{\circ}C$, and SiC was formed by reduction-carbonization of SiO(g) with Al(l, g) and carbon at temperature higher than $1300^{\circ}C$. The products obtained at $1600^{\circ}C$ for 5h consisted of ZrC with lattice constant of $4.679{\AA}$ and crystallite size of $640{\AA}$, and SiC with lattice constant of $4.135{\AA}$ and crystallize size of $500{\AA}$. And also, the mean particle size was about $21.8{\mu}m$.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.47-52
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• 2013

Graphene has been synthesized on 100- and 300-nm-thick Ni/$SiO_2$/Si substrates with $CH_4$ gas (1 SCCM) diluted in mixed gases of 10% $H_2$ and 90% Ar (99 SCCM) at $900^{\circ}C$ by using inductively-coupled plasma chemical vapor deposition (ICP-CVD). The film morphology of 100-nm-thick Ni changed to islands on $SiO_2$/Si substrate after heat treatment at $900^{\circ}C$ for 2 min because of grain growth, whereas 300-nm-thick Ni still maintained a film morphology. Interestingly, suspended graphene was formed among Ni islands on 100-nm-thick Ni/$SiO_2$/Si substrate for the very short growth of 1 sec. In addition, the size of the graphene domains was much larger than that of Ni grains of 300-nm-thick Ni/$SiO_2$/Si substrate. These results suggest that graphene growth is strongly governed by the direct formation of graphene on the Ni surface due to reactive carbon radicals highly activated by ICP, rather than to well-known carbon precipitation from carbon-containing Ni. The D peak intensity of the Raman spectrum of graphene on 300-nm-thick Ni/$SiO_2$/Si was negligible, suggesting that high-quality graphene was formed. The 2D to G peak intensity ratio and the full-width at half maximum of the 2D peak were approximately 2.6 and $47cm^{-1}$, respectively. The several-layer graphene showed a low sheet resistance value of $718{\Omega}/sq$ and a high light transmittance of 87% at 550 nm.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1428-1435
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• 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 Surface Science and Engineering
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• v.38 no.3
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• pp.89-94
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• 2005

We investigate the reaction stability of cobalt and nickel with side-wall materials of $SiO_2\;and\;Si_3N_4$. We deposited 15nm-Co and 15nm-Ni on $SiO_2(200nm)/p-type$ Si(100) and $Si_3N_4(70 nm)/p-type$ Si(100). The samples were annealed at the temperatures of $700\~1100^{\circ}C$ for 40 seconds with a rapid thermal annealer. The sheet resistance, shape, and composition of the residual materials were investigated with a 4-points probe, a field emission scanning electron microscopy, and an AES depth profiling, respectively. Samples of annealed above $1000^{\circ}C$ showed the agglomeration of residual metals with maze shape and revealed extremely high sheet resistance. The Auger depth profiling showed that the $SiO_2$ substrates had no residual metallic scums after $H_2SO_4$ cleaning while $Si_3N_4$ substrates showed some metallic residuals. Therefore, the $SiO_2$ spacer may be appropriate than $Si_3N_4$ for newly proposed Co/Ni composite salicide process.

• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.531-536
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• 2001

SiCl$_4$/CH$_4$/H$_2$계를 사용한 플라즈마 화학증착법(PECVD)으로 실리콘(100) 기판 위에 3C-SiC막을 117$0^{\circ}C$~1335$^{\circ}C$의 온도범위에서 증착하였다. 증착온도, 유입가스비, R$_{x}$ [=CH$_4$/(CH$_4$+H$_2$)], 그리고 r.f. power를 변화시켜 증착막의 결정성에 대해 검토하였다. Thermal CVD에 비해 PECVD법은 박막의 증착속도를 향상시켰다. 증착된 3C-SiC은 (111) 면으로 최대의 우선배향성을 지님을 알 수 있었다. 실리콘 기판 위의 3C-SiC막의 결정성은 R$_{x}$값에 의존하였으며, R$_{x}$가 감소할수록 결정성이 더욱 향상되었다. Free Si가 3C-SiC막과 함께 증착되었으나, 증착온도와 r.f power가 증가함에 따라 free Si의 함량은 감소하였다. 증착온도 127$0^{\circ}C$, 유입가스비 R$_{x}$=0.04, r.f. power가 60W에서 비교적 결정성을 가진 3C-SiC막을 얻을 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2007.02a
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• pp.75-75
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• 2007

• Proceedings of the Korean Vacuum Society Conference
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• 1999.02a
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• pp.30-30
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• 1999

• Proceedings of the Korean Vacuum Society Conference
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• 2002.02a
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• pp.115-115
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• 2002

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.1-5
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• 2009

In this study, we performed growth of InGaN/GaN multi quantum well (MQW) structures on semi-polar (1-10]) GaN facet on 8-degree off oriented stripe patterned (100) Si substratcs by MOVPE. The structural and optical properties of the InGaN/GaN multi quantum well (MQW) structures grown on (1-101) GaN stripe depend on $NH_3$ flow rate, TMI flow rate and growth temperature are characterized by cathodoluminescence (CL) and scanning electron microscopy (SEM). With the decrease of $NH_3$ flow rate, the threading dislocation of (1-101) GaN is considerably reduced. We could control the transition wavelength of InGaN/GaN MQW structures from 391.5 nm to 541.2 nm depend on the growth conditions.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.102-109
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• 2000

It is difficult to meet the cleanliness requirement of $10^{10}/\textrm{cm}^2$ for the giga level device fabrication with mechanical cleaning techniques like scrubbing which is widely used to remove the particles generated during Chemical Mechanical Polishing (CMP) processes. Therefore, the second cleaning process is needed to remove metallic contaminants which were not completely removed during the mechanical cleaning process. In this paper the experimental results for the removal of the metallic contaminants existing on the wafer surface using remote plasma $H_2$ cleaning and UV/$O_3$ cleaning techniques are reported. In the remote plasma $H_2$ cleaning the efficiency of contaminants removal increases with decreasing the plasma exposure time and increasing the rf-power. Also the optimum process conditions for the removal of K, Fe and Cu impurities which are easily found on the wafer surface after CMP processes are the plasma exposure time of 1min and the rf-power of 100 W. The surface roughness decreased by 30-50 % after remote plasma $H_2$ cleaning. On the other hand, the highest efficiency of K, Fe and Cu impurities removal was achieved for the UV exposure time of 30 sec. The removal mechanism of the metallic contaminants like K, Fe and Cu in the remote plasma $H_2$ and the UV/$O_3$ cleaning processes is as follows: the metal atoms are lifted off by $SiO^*$ when the $SiO^*$is evaporated after the chemical $SiO_2$ formed under the metal atoms reacts with $H^+ \; and\; e^-$ to form $SiO^*$.