• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.27.1-27.1
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• 2009

In recent years, ZnO nanostructures have drawn considerable attentions for the development of futuristic electronic devices due to their superior structural and optical properties. As the growth of ZnO nanowires by MOCVD is a bottom-up technique, the nature of substrates has a vital role for the dimension and alignment of the nanowires. However, in the pursuit of next generation ZnO based nanodevices, it would be highly preferred if well-ordered ZnO nanowires could be obtained on various substrates like sapphire, silicon, glass etc. Vertically aligned nanowires were grown on A and C-plane sapphire substrates, where as nanopencils were obtained on R-plane sapphire substrates. In addition, C-axis oriented vertical nanowires were also found using an interfacial layer(aluminum nitride film) on silicon substrates. On the other hand, long nanowires were found on Ga-doped ZnO film on glass substrates. Structural and optical properties of the ZnO nanowires on various substrates were also investigated.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.34-38
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• 2002

TFBAR filters for wireless applications are simulated and fabricated. A CAD model is used to analize the air-gap type single resonator and MBVD model is used far filter design. Aluminum nitride is used as the piezoelectric material with platinum electrodes. To verier the CAD model, simulated and measured results are compared far various top electrode thicknesses, and the agreement is within 0.5 % for the parallel resonance frequency. Various types of the ladder type band pass filters are predicted and their responses are compared with measured frequency data.

• The Korean Journal of Ceramics
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• v.3 no.4
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• pp.257-262
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• 1997

Aluminum nitride(AIN) thin films were deposited on SiO$_2$/Si substrates by reactive sputtering for the application of SAW devices. The major deposition parameters such as pressure, nitrogen fraction, rf power, substrate distance were changed to find out the optimal condition for c-axis oriented thin films on an amorphous substrate. The effects of deposition parameters on the crystal structure, residual stress, and growth morphology of thin films were characterized by XRD, SEM, and TEM. The FWHM of (002) rocking curve of the films deposited at the proper condition was lower than 2.2$^{\circ}$(C=0.93$^{\circ}$). Cross-sectional TEM showed that self-aligned structure was developed just after slightly random growth at the initial stage. The frequency characteristics of test device fabricated from AIN thin films confirmed their piezoelectric property and applicability for SAW devices.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.147-150
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• 2006

A new class of heat transfer fluid with higher thermal conductivity, called nanofluids has been developed by Dr. S. Choi about decade ago. Many exciting experimental and theoretical results have been reported worldwide to predict the thermal conductivity enhancement of nanofluids, however, they sometimes show excessive large discrepancies between each other. This kind of disagreements in thermal conductivity data is partly ascribable to the accuracy of the measuring apparatus, that is, mostly used THM(transient hot-wire method). New thermal conductivity measuring method whose principle is different from that of conventional THM is proposed in this article and measurements and uncertainty analysis were made for the three nanofluid samples with different particle concentration of pure, 2% and 4% of AlN nanofluids.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.3-6
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• 2002

In this paper, Thin film bulk acoustic resonate.(TFBAR) fillers tuned by gold plated on-wafer inductors are presented. The air-gap type TEBAR is used with aluminum nitride(AIN) as piezoelectric material and platinum as top and bottom electrodes. Inductor equivalent model and modified Butterworth-Van Dyke(MBVD) model are employed for the frequency tuning of fabricated TFBAR bandpass filters. Fabricated inductor has inductance of 3 nH and Q factor of about 8 at 2 ㎓. It is clearly revealed that inductor tuning can enhance the bandwidth of ladder filters and improve out-of-band rejection characteristic around 10㏈.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.4
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• pp.135-138
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• 2016

It was observed that the single grain of crystallite growth behavior in AlN (Aluminum Nitride) single crystal growth by PVT (Physical Vapor Transport) method. The single grain of AlN was grown in sequent experiments and adjacent crystallites were joined together after small grain was grown. The sequential results of those grains observed by stereoscopic microscope were reported.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.509-512
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• 2001

Aluminum nitride(AlN) thin films were deposited on silicon substrates using RF magnetron sputtering at various deposition conditions and investigated the characteristics. It was used XRD, AES, SEM, and HP-4145B semiconductor parameter analyzer to analysis deposited AlN thin films. The deposition conditions for the good c-axis orientation were 100 W of RF power, $200^{\circ}C$ of substrate temperature and 15 mTorr of working pressure. The leakage current density was less then $1.3{\times}10^{-7}A/cm^{2}$. And it was also investigated the etching properties of deposited AlN thin films for application.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.900-902
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• 1999

This paper deals with the interrupting characteristics of fuses element in different media of arc extinguisher. Aluminum hydro-oxide, boron nitride, silica and there size have been investigated here for their prospects as filling media in heavy current, high breaking capacity fuses. The result of these study are compared with those on silica sand at high current. This study demonstrates that silica sand is far superior filler in fuses for heavy current interrupting then the compound tested.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.9 s.252
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• pp.898-904
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• 2006

A new method measuring thermal conductivity of fluids is proposed in this research. It is based on the steady state heat transfer from a hot central cylinder to a cold outer cylinder located concentrically. This method guarantees more stable measurement than conventional THM(transient hot-wire method) due to its simplicity of theoretical principle. Measurements was made for the three nanofluid samples with different particle concentration of pure, 2% and 4%. Nanofluids are made by mixing the pure transformer oil with AlN nano particles. Design of the sensor module and experimental procedures are explained and comparison of the measuring data between present method and THM was made in detail.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.50-50
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• 2011

The aluminum nitride films were prepared by RF magnetron sputtering using an AlN ceramic target. The crystallinity, grain size, Al-N bonding and thermal conductivity were investigated in dependence on the plasma power densities (4.93, 7.40, 9.87 W/$cm^2$) during sputtering. High thermal conductivity is important properties of A1N passivation layer for functioning properly in thermal inkjet printhead. The crytallinity, grain size, Al-N bonding formation and chemical composition were observed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The AlN thin film was changed from amorphous to crystalline as the power density was increased, and the largest grain size appeared at medium power density. The near stoichiometry Al-N bonding ratio was acquired at medium power density. So, we know that the AlN thin film had better thermal conductivity with crystalline phase and near stoichometry Al-N bonding ratio at 7.40 W/$cm^2$ power density.