• Korean Journal of Materials Research
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• v.15 no.11
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• pp.730-734
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• 2005

Cr-Al-Si-N coatings were deposited on WC-Co substrates by a hybrid coating system of arc ion plating and DC magnet :on sputtering technique in $N_2/Ar$ mixture. The Cr-tll-Si-N coatings were synthesized with different Si contents. Their microstructure and mechanical properties were systematically investigated. The average size of crystallites largely decreases with the increase of Si content compared with Cr-Al-N. The microhardness of Cr-Al-Si-N coatings largely increases from 24 to 55 GPa. The enhanced hardness is believed to originate from the microstructural change by the fine composite microstructure of Cr-Al-N coatings with Si addition. The average friction coefficient of Cr-Al-Si-N coatings decreases from 0.84 to 0.45 with increasing Si content up to $16\;at.\%$.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.150-154
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• 2000

We investigated the quantum well intermixing (QWI) of a compressively strained InGaAs/InGaAsP multiple quantum well (MQW) by using impurity free vacancy diffusion technique. The samples with InGaAs/$SiO_2$ capping layer showed a higher degree of intermixing compared to that of InP/$SiO_2$ capping layer after rapid thermal annealing (RTA). Band-gap shift difference as large as 123 meV (195 nm) was observed between samples capped with InGaAs/$SiO_2$ and with InP/$SiO_2$ layer at RTA temperature of $700^{\circ}C$. Using the InGaAs/$SiO_2$ cap layer, the band-gap wavelength of MQW was changed by the intermixing from 1.55 $\mu\textrm{m}$ band to 1.3 $\mu\textrm{m}$ band with a wavelength shift of a 237 nm. The transform from MQW structure to homogenous alloy was observed above the RTA temperature of $700^{\circ}C$.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.507-514
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• 1993

The solid state reaction of Mo/Si multilayer thin films produced by RF magnetron sputtering technique was examine dusing differential scanning calorimetry (DSC) and x-ray diffraction, and explained in view of two concepts, effective drivig force and effective heat of formation. In constant scanning rate DSC, there were two exothermic peks which corresponded to the formation of h-MoSi2 and t-MoSi2 , respectively. The activation energyfor theformation of h-MoSi2 was 1.5eV , and that of t-MoSi2 was 7.8eV. Nucleation wa stherate controlling mechanism for each of the silicide formation. Amorphous phase was not formed , which was consistent withtheprediction by the concept of effective driving force. h-MoSi2 the first crystalline phase, was considered to have lower interfacial free energy than t-MoSi2 and by increasing temperature it was transformed into more stable t-MoSi2.

• ETRI Journal
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• v.25 no.4
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• pp.247-252
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• 2003

This paper presents results from experiments on laser-annealed SiGe-selective epitaxial growth (LA-SiGe-SEG). The SiGe-SEG technology is attractive for devices that require a low band gap and high mobility. However, it is difficult to make such devices because the SiGe and the highly doped region in the SiGe layer limit the thermal budget. This results in leakage and transient enhanced diffusion. To solve these problems, we grew in situ doped SiGe SEG film and annealed it on an XMR5121 high power XeCl excimer laser system. We successfully demonstrated this LA-SiGe-SEG technique with highly doped Ge and an ultra shallow junction on p-type Si (100). Analyzing the doping profiles of phosphorus, Ge compositions, surface morphology, and electric characteristics, we confirmed that the LA-SiGe-SEG technology is suitable for fabricating high-speed, low-power devices.

• Journal of the Korean institute of surface engineering
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• v.38 no.4
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• pp.174-178
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• 2005

Chemical vapor deposition technique has been used to grow epitaxial SiC thin films on Si wafers using tetramethylsilane(TMS) precursor. The films were observed to grow along (110) direction of 3C-SiC at $800^{\circ}C$. The quality of the films was significantly influenced by the TMS flow rate and growth temperature. Nanocrystal SiC films were grown at flow rates of TMS 10 sccm with $H_2$ carrier gas of 100 sccm. The temperature and gas pressure in the reactor have a great influence on the crystallinity and morphology of the SiC film grown. The growth mechanism of the SiC film on the Si substrate without the carbonization process was discussed based on the experimental results.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.14-19
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• 1999

Using a single precursor of hexamethyldisilane $(Si_{2}(CH_{3})_{6})$, $\beta$-SiC film was successfully deposited on a Si substrate at $1100^{\circ}C$ by a chemical vapor deposition method. Selectivity of SiC deposition on a Si substrate partially covered with a masking material was investigated by introducing HCl gas into hexamethyldisilane/$H_{2}$ gas system during the deposition. The schedule of the precursor and HCl gas flows was modified so that the selectivity of SiC deposition between a Si substrate and a mask material should be improved. It was confirmed that the selectivity of SiC deposition was improved by introducing HCl gas. Also, the pulse gas flow technique was effective to enhance the selectivity.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.25-29
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• 1998

Sliding wear test and surface characterization techniques such as micro-Raman spectroscopy were employed to determine the effect of whisker content and orientation on the friction and wear behavior of SiC whisker reinforced alumina. Composites containing unidirectionally oriented whiskers were fabricated by novel technique Addition of SiC whiskers up to 20 vol.% lowered the friction and improved wear resistance. The results of this study indicated that highly disordered graphite and size of the layer behind the whiskers were responsible for variation of wear rate and friction coefficient.

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.319-324
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• 2010

Screen printable $MoSi_2$ paste and its ceramic sheet heater were investigated. $MoSi_2$ powder without $Mo_5Si_3$ second phase, which causes so-called pest phenomena, was synthesized by SHS technique. Over glaze was also developed for preventing pest phenomenon. The maximum temperature of $MoSi_2$ ceramic heater was over $500^{\circ}C$. After several heat up and cooling cycle, the $MoSi_2$ heater reveals pest phenomenon. Conductive $MoSi_2$ paste could be used in electronic ceramics, i.e., MLCC, LTCC, HTCC, and etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.409-412
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• 2004

Edge termination technique is essential fer the fabrication of high volage devices. A proper edge termination technique is also needed in the fabrication of Silicon Carbide power devices for obtaining a stable high blocking voltage properties. Among the many techniques, the field plate formation is the easiest one that can utilize it for commercial usage. The growth of thick thermal oxide is difficult for SiC, however. In this paper, 6A grade SiC schottky barrier diodes(SBD) were fabricated with field plate edge termination. The oxides which is field plate were formed various methods such as dry oxidation, 10% $N_2O$ nitrided oxidation and PECVD deposition. The reverse characteristics of the SiC SBD with various oxide field plate were investigated.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1855-1862
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• 2023

Graphite crucibles are used for melting uranium and its alloys in VIM furnace. Various coating materials namely Al₂O₃, ZrO₂, MgO etc. are applied on the inner surface of the crucibles using paint brush or thermal spray technique to mitigate U-C interaction. These leads to significant amount of carbon pick-up in uranium. In this study, the attempts are made to develop multilayer coatings comprising of SiC/Y₂O₃ and Mo/Y₂O₃ on graphite to study the feasibility of minimizing U-C interaction. The parameters are optimized to prepare SiC coating of about 70㎛ thickness using CVD technique on graphite coupons and subsequently Y₂O₃ coating of about 250㎛ thickness using plasma spray technique. Molybdenum and Y₂O₃ layers were deposited using plasma spray technique with 70㎛ and 250㎛ thickness, respectively. Interaction studies of the coated graphite with molten uranium at 1450℃ for 20 min revealed that Y₂O₃ coating with SiC interlayer provides physical barrier for uranium-graphite interaction, however, this led to the physical separation of coating layer. Y₂O₃ coating with Mo interlayer provided superior barrier effect showing no degradation and the coatings remained intact after interaction tests. Therefore, the Mo/Y₂O₃ coating was found to be a promising solution for minimizing carbon pick-up during uranium/uranium alloy melting.