• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.13-16
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• 2009

In this study, AlN thin films were deposited on a polycrystalline (poly) 3C-SiC buffer layer for surface acoustic wave (SAW) applications using a pulsed reactive magnetron sputtering system. AFM, XRD and FT-IR were used to analyze structural properties and preferred orientation of the AlN/3C-SiC thin film. Suitability of the film in SAW applications was investigated by comparing the SAW characteristics of an interdigital transducer (IDT)/AlN/3C-SiC structure with the IDT/AIN/Si structure at 160 MHz in the temperature range $30-150^{\circ}C$. These experimental results showed that AlN films on the poly 3C-SiC layer were highly (002) oriented. Furthermore, the film showed improved temperature stability for the SAW device, $TCF\;=\;-18\;ppm//^{\circ}C$. The change in resonance frequency according to temperature was nearly linear. The insertion loss decrease was about $0.033dB/^{\circ}C$. However, some defects existed in the film, which caused a slight reduction in SAW velocity.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.373-376
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• 2010

The characteristics of thermal-resistance catalyst for $N_2O$ propellant decomposition were studied in the present study. Si was added to the $Al_2O_3$ support to stabilize its surface area at high temperature (> $1000^{\circ}C$). Ru was used as a catalyst for $N_2O$ decomposition. The prepared catalysts were characterized using SEM, EDS and XRD analysis, and $N_2O$ conversion was measured as reaction temperatures. The Ru/$Al_2O_3$-Si catalyst showed better performance than Ru/$Al_2O_3$ catalyst.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.706-712
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• 1997

AlN(Aluminium Nitride) thin films were prepared using by RF sputtering method on the Si(100) and Si(111) substrates as the parameters of the substrate temperature, RF power, sputtering duration and the $N_2$/Ar ratio and investigated by X-ray diffraction, IR spectrometry, n&k analyzer. For the Si(100) substrate, the AlN thin films of (101) orientation were obtained under the conditions of room temperature and the nitrogen of 60 vol.%. For the Si(111) substrate, the (002) AlN thin films were obtained under the nitrogen of 100 vol.%. In case of the thin film prepared in the condition of above 60 vol.% of the nitrogen, the average value of the surface roughness of the film was 151$\AA$. From the changes of the half widths of E$_1$[TO] phonon bands at the wavenumber of 680$cm^{-1}$ /, it were compared of the crystallinities of the films which were grown under the different conditions. The thicknesses of AlN films were decreased dramatically in the region of the nitrogen of 40~60 vol.%. Its due to the nitridation of the Al target surface and getting low of the sputtering yield by the $N_2$/Ar ratio being increased.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.12-12
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• 2006

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.150-150
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• 1997

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.32-32
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• 1997

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.224-228
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• 2000

Using a small amount of additives and amorphous Si₂N₂O powders, O-SiAlON ceramics have been hot-pressed and its microstructure and mechanical properties were investigated. Scandium oxide was demonstrated to be an effective densification additive for O-SiAlON. Amorphous Si₂N₂O was densified at relatively low temperatures and a microstructure with acicular grains was developed. Fine grains found in materials obtained from amorphous powders suggest that nucleation and crystallization of O-SiAlOH is relatively easy compared with the Si₃N₄-SiO₂reaction.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.599-603
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• 1999

We have investigated the growth characteristics of thick GaN on Sim substrate with AlN and low temperature GaN buffer layer. The vertical hydride vapor phase epitaxy system with $GaCl_3$ precursor was used for growth of GaN. AlN and GaN buffer layer were deposited on Si substrate to reduce the lattice mismatch and the thermal expansion coefficient mismatch between si and GaN. Optimization of deposition condition for AlN and low temperature GaN buffer layers were carried out. We studied the effects of growth temperature, V/III ratio on the properties of thick GaN. Surface morphology, growth rate and crystallinity of thick GaN were measured using Atomic Force Microscopy (AFM), $\alpha-step$-, Scanning Electron Microscopy (SEM) and X-Ray Diffractometer(XRD).

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.165-165
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• 2003

The growth of GaN on Si is of great interest due to the several advantages low cost, large size and high-quality wafer availability as well as its matured technology. The crystal quality of GaN is known to be much influenced by the surface pretreatment of Si substrate [1]. In this work, the properties of GaN overlayer grown on ion implanted Si(111)and bare Si(111) have been investigated. Si(111) surface was treated ion implantation with 60KeV and dose 1${\times}$10$\^$16//$\textrm{cm}^2$ prior to film growth. GaN epilayers were grown at 1100$^{\circ}C$ for 1 hour after growing AlN buffer layers for 15-30 minutes at 1100$^{\circ}C$ with metal organic chemical vapor deposition (MOCVD). The properties of GaN epilayers were evaluated by X-Ray Diffraction (XRD), Scanning electron microscope (SEM) Photoluminescence (PL) at room temperature and Hall measurement The results showed that the GaN on ion implanted Si(111) markedly affected to the structural, optical and electrical characteristic of GaN layers.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.122-123
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• 2007

Bias voltage를 달리하여 cathodic arc plasma 방법으로 Si 기판 위에 성장시킨 TiCrAlSiN 코팅막의 미세구조를 투과전자현미경으로 관찰하였다. -200 V에서 0 V로 bias voltage가 변화함에 따라 'nano-multilayered' 구조가 무너지면서 '주상형(columnar)'구조로 코팅막의 미세구조가 변함을 알 수 있었고, EDS line scan을 통해 multilayer의 화학적 조성 변화를 확인하였다.