• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.35-41
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• 1992

Ultra-thin silicon nitride films were fabricated with ECR(Electron cyclotron Resonance) nitrogen plasma at room temperature. Film thickness was about 50$\AA$ after nitridation for 1min at microwave power of 1000W, RF power of 500W, and NS12T pressure of ${\times}10^{-3}$ torr. 50$\AA$ fo nitride film was grown within 1 min and no appreciable growth occured thereafter. Dielectric breakdown strength and leakage current density in Al/SiN/Si structure were measured to be about 7-11 MV/cm and ${\times}10^{-10}~5{\times}10^{-10}A/cm^{2}$, respectively. Observed linear relationship in 1n(J/E)-vs-E$^{1/2}$ and no polarity-dependence of the leakage current indicated that the Poole-Frenkel emission is mainly responsible for the conduction in this nitrided silicon films.

• Journal of the Korean Vacuum Society
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• v.10 no.4
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• pp.403-410
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• 2001

Acceleration in integration density and speed performance of ULSI circuits require miniaturization of CMOS and interconnections as well as higher current density capabilities for transistors. A leading candidate to substitute Al-alloy is Cu, which has lower resistivity and higher melting point. So we can expect much higher electromigration resistance. In this paper, we are going to explain the major features of EM for MOCVD Cu according to variant conditions. We compared the life time and activation energy of MOCVD Cu with those of I-beam Cu and AA in the same conditions. The electromigration experiments were performed with Cu/Al/TiN multilayer. Experimental results shows that the deposition rate and electromigration characteristics of Cu thin film were improved by the Al interlayer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.107-108
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• 2006

ZnO is a promising material for UV or blue LEDs p-Type ZnO thin films which are imperative for the p-n junction of LEDs are difficult to achieve because of strong compensation of intrinsic defects such as zinc interstitial and oxygen vacancy. The method of codoping group three elements and group five elements is effective for the realization of p-type ZnO films. In this study, We codoped N and Al m ZnO thin films by RF magnetron sputtering and annealed the films in sputtering chamber. Some films showed p-type conductivity m Seeback effect measurement.

• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.154-158
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• 2001

The steps for the generation of very thin GaN films on ultrathin AlN/6H-SiC surface by alternating a pulsative supply (APS) of trimethyl gallium and NH3 gases have been examined by ASED-MO calculations. We postulate that the gallium cul ster was formed with the evaporation of CH4 gases via the decomposition of trimethyl gallium (TMG), dimethyl gallium (DMG), and monomethyl galluim (MMG). During the injection of NH3 gas into the reactor, the atomic hydrogens were produced from the thermal decomposition of NH3 molecule. These hydrogen gases activated the Ga-C bond cleavage. An energetically stable GaN nucleation site was formed via nitrogen incorporation into the layer of gallium cluster. The nitrogen atoms produced from the thermal degradation of NH3 were expected to incorporate into the edge of the gallium cluster since the galliums bind weakly to each other (0.19 eV). The structure was stabilized by 2.08 eV, as an adsorbed N atom incorporated into a tetrahedral site of the Ga cluster. This suggests that the adhesion of the initial layer can be reinforced by the incorporation of nitrogen atom through the formation of large grain boundary GaN crystals at the early stage of GaN film growth.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.657-659
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• 2004

Trivalent cerium ($Ce^{3+}$) activated yttrium aluminum garnet ($Y_3Al_5O_{12}$, YAG) phosphor thin films were deposited on quartz glass substrates by rf magnetron sputtering. The effects of sputtering parameters and annealing condition on the luminescent properties were investigated. The sputtering parameters were $O_2$/Ar gas ratio, rf power, and deposition time. The films were annealed at 1200 $^{\circ}C$ for 5 hours in $N_2+$vacuum atmosphere. Polycrystalline YAG:Ce thin film phosphor could be obtained with a gas ratio of $O_2$/(Ar+$O_2$)=0.5 after post-annealing. PL spectra excited at 450 nm showed a yellow single band at 550 nm.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1430-1432
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• 1997

A solar cell conversion effiency was degraded by grain boundary effect in polycrystalline silicon. To reduce these effects of the grain boundaries, we investigated various influencing factors such as preferential chemical etching of grain boundaries, grid design, transparent conductive thin film, and top metallization along grain boundaries. Pretreatment in $N_2$ atmosphere and gettering by $POCl_3$ and Al were performed to obtain polycrystalline silicon of the reduced defect density. Structural, electrical, and optical properties of solar cells were characterized. Improved conversion efficiencies of solar cell were obtained by a combination of Al diffusion into grain boundaries on rear side, fine grid finger, top Yb metal grid on Cr thin film of $200{\AA}$ and buried contact metallization along grain boundaries.

• Korean Journal of Materials Research
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• v.16 no.3
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• pp.178-182
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• 2006

A single electro-discharge-sintering (EDS) pulse (1.0 kJ/0.7 g), from a $300{\mu}F$ capacitor, was applied to atomized spherical Ti-6Al-4V powder in a low vacuum to produce porous-surfaced implant compacts. A solid core surrounded by a porous layer was formed by a discharge in the middle of the compact. XPS (X-ray photoelectron spectroscopy) was used to study the surface characteristics of the implant material. C, O, and Ti were the main constituents, with smaller amounts of Al, V, and N. The implant surface was lightly oxidized and was primarily in the form of $TiO_2$ with a small amount of metallic Ti. A lightly etched EDS implant sample showed the surface form of metallic Ti, indicating that EDS breaks down the oxide film of the as-received Ti-6Al-4V powder during the discharge process. The EDS Ti-6Al-4V implant surface also contained small amounts of aluminum oxide in addition to $TiO_2$. However, V detected in the EDS Ti-6Al-4V implant surface, did not contribute to the formation of the oxide film..

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.226-229
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• 2004

A stoichiometric mixture of evaporating materials for $CuAlSe_2$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CuAlSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $680^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuAlSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.68{\times}10^{-4}\;eV/K)T^2/(T+155K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CuAlSe_2$ have been estimated to be 0.2026 eV and 0.2165 eV at 10K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $CuAlSe_2$. The three photocurrent peaks observed at 10K are ascribed to the $A_1-$, $B_1-$, and $C_1$-exciton peaks for n = 1.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.8
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• pp.7-12
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• 2010

In this paper, $C_{60}$ based Organic thin film transistor OTFTs) have been fabricated using BPhen(Bathophenanthroline) and BPhen doped with Cs interlayers between $C_{60}$ active layer and Al electrodes to improve the electrical performance. The addition of the BPhen layer resulted in enhanced performances by reducing surface roughness between organic-metal interface. And the contact resistance was reduced by using the BPhen doped with Cs interlayer with co-evaporation method. These performances suggests that the $C_{60}$ based OTFT with BPhen doped with Cs interlayer is a promising application in the fabrication of n-type organic transistors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.556-561
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• 2008

This paper reports the characteristics of piezoelectric microspeakers that are audible in open air with high quality piezoelectric AlN thin film according to the materials properties. When we use a tensile-stressed silicon nitride diaphragm as a supporting layer, the Sound Pressure Level (SPL) is relatively small and constant at low frequency region and shows about 70 dB at 10 kHz. However, in case of a compressively stressed composite diaphragm, the SPL of the fabricated microspeakers shows higher output pressure than those of a tensile-stressed diaphragm. It produces more than 66 dB from 100 Hz to 15 kHz and the highest SPL is about 100 dB at 9.3 kHz with $20V_{peak-to-peak}$, sinusoidal input biases and at 10 mm distances from the fabricated microspeakers to the reference microphone. From the experimental results, it is superior to have a compressively composite diaphragm in order to produce a high SPL in piezoelectric microspeaker.