• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.41-46
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• 2013

Efficient and inexpensive solar cells are necessary for photo-voltaic to be widely adopted for mainstream electricity generation. For this to occur, the recombination losses of charge carriers (i.e. electrons or holes) must be minimized using a surface passivation technique suitable for manufacturing. Recently it has been shown that aluminum oxide thin films are negatively charged dielectrics that provide excellent surface passivation of silicon solar cells to attract positive-charged holes. Especially aluminum oxide thin film is a quite suitable passivation on the rear side of p-type silicon solar cells. This paper, it demonstrate the interfacial microstructure and electrical properties of mono-crystalline silicon surface passivated by $Al_2O_3$ films during firing process as applied for screen-printed solar cells. The first task is a comparison of the interfacial microstructure and chemical bonds of PECVD $Al_2O_3$ and of PEALD $Al_2O_3$ films for the surface passivation of silicon. The second is to study electrical properties of double-stacked layers of PEALD $Al_2O_3$/PECVD SiN films after firing process in the temperature range of $650{\sim}950^{\circ}C$.

• Journal of the Mineralogical Society of Korea
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• v.17 no.3
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• pp.267-275
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• 2004

A hydrothermal process was used to synthesize dioctahedral smectite from dickite [$A1_2$$Si_2$$O_{5}$ $(OH)_4$], Dickite was previously activated by heating at $800^{\circ}C$ far 4 hours with $Na_2$$CO_3$. After the heat-treatment, $SiO_2$ was added for stoichiometry, The autoclaving was carried out in closed stainless steel vessel (about 1 liter) at the condition of various temperature, pressure, time etc. High quality smectite could be obtaind by heating at $290^{\circ}C$ under the pressure of 60 kgf/$\textrm{cm}^2$ for 48 hours. This experiment reveals that pH of the solution was an important factor and should be maintained at 10 to 11 for the formation of dioctahedral smectite. The synthesized smectite was identified as Na-beidellite by the treatment of ethylene glycol and Greene-Kelly test.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.305-308
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• 2004

We present a novel process for the ultra low temperature (<150$^{\circ}C$) polycrystalline silicon (ULTPS) TFT for the flexible display applications on the plastic substrate. The sequential lateral solidification (SLS) was used for the crystallization of the amorphous silicon film deposited by rf magnetron sputtering, resulting in high mobility polycrystalline silicon (poly-Si) film. The gate dielectric was composed of thin $SiO_2$ formed by plasma oxidation and $Al_2O_3$ deposited by plasma enhanced atomic layer deposition. The breakdown field of gate dielectric on poly-Si film showed above 6.3 MV/cm. Laser activation reduced the source/drain resistance below 200 ${\Omega}$/ㅁ for n layer and 400 ${\Omega}$/ㅁ for p layer. The fabricated ULTPS TFT shows excellent performance with mobilities of 114 $cm^2$/Vs (nMOS) and 42 $cm^2$/Vs (pMOS), on/off current ratios of 4.20${\times}10^6$ (nMOS) and 5.7${\times}10^5$ (PMOS).

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.116-123
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• 1997

A chemically stabilized $\beta$-cristobalite, which is stabilized by stuffing cations of $Ca^{2+}$ and $Al^{3+}$, was prepared by a solution-polymerization route employing Pechini resin or PVA solution as a polymeric carrier. The polymeric carrier affected the crystallization temperature, morphology of calicined powder, and particle size distribution. In case of the polyvinyl alcohol (PVA) solution process, a fine $\beta$-cristobalite powder with a narrow particle size distribution (average particle size : 0.3$\mu\textrm{m}$) and a BET specific surface area of 72 $\m^2$/g was prepared by an attrition-milling for 1 h after calcination at 110$0^{\circ}C$ for 1h. Wider particle size distribution and higher specific surface area were observed for the $\beta$-cristobalite powder derived from Pechini resin. The cubie(P1-to-tetraganalb) phase transformation in polynystalline $\beta$-cristobalite was induced at approximately 18$0^{\circ}C$. Like other materials showing transformation toughening, a critical size effect controlled the $\beta$-to-$\alpha$ transformation. Densifed cristobalite sample had some cracks in its internal texture after annealing. The cracks, occurred spontaneoulsy on cooling, were observed in the sample with an average grain sizes of 4.0 $\mu\textrm{m}$ or above. In case of the sintered cristobalite having a composition of CaO.$2Al_2O_3$.40SiO$_2$, small amount of amorphous phase and slow grain growth during annealing were observed. Shear stress-induced transformation was also observed in ground specimen. Cristobalite having a composition of CaO.2Al2O3.80SiO2 showed a more sensitive response to shear stress than the CaO.$2Al_2O_3$.40SiO$_2$ type cristobalite. Shear-induced transformation resulted in an increase of volume about 13% in $\alpha$-cristobalite phase on annealing for above 10 h in the case of the former composition.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.144-152
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• 2004

The aim of this study was to evaluate the resistance to degradation of three commercial compomers in an alkaline solution. Dyract(Dentsply), Elan(Kerr) and F-2000(3M) polyacid modified resin composites(compomers) were used in this study. The resistance to degradation was evaluated on the basis of mass loss(%), degradation $depth({\mu}m)$ and Si, Al, Ba loss(ppm). The results were as follows : 1. The mass loss of each brand was $1.42%{\sim}2.14%$ and there was no statistically significant difference of mass loss among Dyract, F2000 and Elan. 2. The degradation layer depth of each brand was $182.92{\sim}227.7{\mu}m$ and there was no statistically significant difference of degradation layer depth among Dyract, F2000 and Elan. 3. There was statistically significant differences in Si-loss and Al-loss among three compomers (p<0.05). Si loss was the highest value in Dyract and Al loss was the highest value in F2000. 4. There was statistically significant correlation between mass loss and degradation layer depth (r=0.60, p<0.05). 5. In SEM finding, there was some destruction of compomer matrix-filler interface in post-exposure specimen to NaOH solution. As the matrix decreased, the filler particles distinguished and the periphery of the filler particles appeared whitish color due to degradation.

• Resources Recycling
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• v.5 no.1
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• pp.3-8
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• 1996

CZS(2Ca0 , SiO\ulcorner) phase of cement clinkcr was obtaincd by melting mixcd four indnstrial wasles of limestone sludge, waste Foundry sand, coal lly ash fiorn power plants and chernicas glasses. The effect ot mixing ratio of four rvastc mater~als ou the composnlg phascs in melled slag was investigated. Thc mixed wastes were meltcd to slag by heat under a constant basicity at 1370C. The shg consisted of p -CIS and C,AS(2CaO - A I P , . SiO,). The ratio of two phases was varied with mixing ~atioo f the waste materials. In order Lo increasc the amount ot j -C2S phase, the coal fly ash content should be reduced, while amount of the chemical glass be increased. The coal fly ash contcnt was the most imporlant factor in controlling phases of thc melted-slag.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.56-63
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• 1994

The effects of sulfur treatments on the barrier heithts of Schottky contacts and the interface-state density of metal-insulator-semiconductor (MIS) capacitors on InP have been investigated. Schottky contacts were formed by the evaporation of Al, Au, and Pt on n-InP substrate before and after (NH$_{4}$)$_{2}$S$_{x}$ treatments, respectively. The barrier height of InP Schottky contacts was measured by their current-voltage (I-V) and capacitance-voltage (C_V) characteristics. We observed that the barrier heights of Schottky contacks on bare InP were 0.35~0.45 eV nearly independent of the metal work function, which is known to be due to the surface Fermi level pinning. In the case of sulfur-treated Au/InP ar Pt/InP Schottky diodes, However, the barrier heights were not only increased above 0.7 eV but also highly dependent on the metal work function. We have also investigated effects of (NH$_{4}$)$_{2}$S$_{x}$ treatments on the distribution of interface states in Si$_{3}$N$_{4}$InP MIS diodes where Si$_{3}$N$_{4}$ was provided by plasma enhanced chemical vapor deposition (PECVD). The typical value of interface-state density extracted feom 1 MHz C-V curve of sulfur-treated SiN$_{x}$/InP MIS diodes was found to be the order of 5${\times}10^{10}cm^{2}eV^{1}$. This value is much lower than that of MiS diodes made on bare InP surface. It is certain, therefore, that the (NH$_{4}$)$_{2}$S$_{x}$ treatment is a very powerful tool to enhance the barrier heights of Au/n-InP and Pt/n-InP Schottky contacts and to reduce the density of interface states in SiN$_{x}$/InP MIS diode.

• Korean Journal of Materials Research
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• v.18 no.6
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• pp.339-346
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• 2008

Single-crystal $ZnIn_2S_4$ layers were grown on a thoroughly etched semi-insulating GaAs (100) substrate at $450^{\circ}C$ with a hot wall epitaxy (HWE) system by evaporating a $ZnIn_2S_4$ source at $610^{\circ}C$. The crystalline structures of the single-crystal thin films were investigated via the photoluminescence (PL) and Double-crystal X-ray rocking curve (DCRC). The temperature dependence of the energy band gap of the $ZnIn_2S_4$ obtained from the absorption spectra was well described by Varshni's relationship, $E_g(T)=2.9514\;eV-(7.24{\times}10^{-4}\;eV/K)T2/(T＋489K)$. After the as-grown $ZnIn_2S_4$ single-crystal thin films was annealed in Zn-, S-, and In-atmospheres, the origin-of-point defects of the $ZnIn_2S_4$ single-crystal thin films were investigated via the photoluminescence (PL) at 10 K. The native defects of $V_{Zn}$, $V_S$, $Zn_{int}$, and $S_{int}$ obtained from the PL measurements were classified as donor or acceptor types. Additionally, it was concluded that a heat treatment in an S-atmosphere converted $ZnIn_2S_4$ single crystal thin films into optical p-type films. Moreover, it was confirmed that In in $ZnIn_2S_4$/GaAs did not form a native defects, as In in $ZnIn_2S_4$ single-crystal thin films existed in the form of stable bonds.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.199-209
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• 2000

Particles reinforced MMCs have higher specific modulus, higher specific strength, better properties at elevated temperatures and better wear resistance than monolithic metals. But the coefficient of thermal expansion(CTE) of Al6061 is 5 times larger than that of SiCp. The discrepancy of CTE makes some residual stresses inside of MMCs. This work investigates Si$C_p$/Al6061 composites at high temperatures in the microscopic view by three-dimensional elasto-plastic finite element analyses and compares the analytical results with the experimental ones. The theoretical model is not able to consider the nonuniform shape of particle. So the shape of particle is assumed to be perfect global shape. And also particle distribution is not homogeneous in experimental specimen. It is assumed to be homogeneous in simulation model. The type of particle distribution is face-centered cubic array(FCC array). Furthermore, non-homogeneous distribution is modeled by combination of several volume fractions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.865-868
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• 2002

$SnO_2$ powders were prepare by precipitating $Sn(OH)_4$ from an aqueous solution of $SnCl_4{\cdot}5H_2O$, pH 9.5. The effects of stability and sensitivity of $SnO_2$ thick film sensors added with various amounts, $SiO_2$, $Al_2O_3$, $ZrO_2$, $TiO_2$ have been investigated. It is shown that the 3wt% $Al_2O_3$ or $SiO_2$ can improve the stability of $SnO_2$ gas sensor at an operating temperature of $350^{\circ}C$.