• Journal of the Korean institute of surface engineering
• /
• v.27 no.2
• /
• pp.99-108
• /
• 1994

Films of glass-ceramics $Li_2O-Al_2O_3-SiO_2$(LAS)system were prepared on substrate of an iron plate(SCP) by sol-gel technique using metal alkoxide such as Si$(OC_2H_5)_4$,Al$(OC_2H_9)_3$) and Ti$(OC_2H_6)_4$). Sol which was made by means of simple spray coating, on the substrate was hydrolyzed at 75~$80^{\circ}C$ in moisture cabinet (80~90 % humidity) to form the multicomponent gel. The films up to about 0.8~1.0$mu extrm{m}$ in thickness can be obtained by repeating operation, spraylongrightarrowhydrolysis and condensationlongrightarrowdryinglongrightarrowheating and crystallization at $700^{\circ}C$ for 3~5min. The far-infrared radiation spectra of the coated films on substrate were examined by FT-IR and of films was also observed by scanning electron micrograph technique. The thermal evaluation of the gel-film is followed by TG/DTA measurements. The structure evaluation is followedd X-ray diffraction. These results suggest that this process is applicable to far-infrared radiat at thin film technique.

• The Journal of Engineering Research
• /
• v.3 no.1
• /
• pp.215-222
• /
• 1998

The effect of La and Si addition of the thermal stabilization of $\gamma-alumina$ powers have been studied. Reagent grade $La(NO_3)_3{\cdot}6H_2O$ and $Si(OC_2H_5)_4$ were used as starting materials. These additives were introduced by wet impregnation method. Both La and Si additives suppressed the sintering of alumina and were found to be good thermal stabilizers of $\gamma-alumina$. Especially, Si drastically suppressed the phase transition of alumina at high temperatures. The major mechanisms for the thermal stabilization of alumina were seemed to be new phase formation and retardation of surface diffusion by addition of La or Si into alumina matrix.

• Journal of the Korean Ceramic Society
• /
• v.28 no.5
• /
• pp.390-398
• /
• 1991

$\beta$-Sialon powder was prepared from Wando pyrophyllite by the carbothermic reduction and nitridation at 135$0^{\circ}C$ for 10 h nitrogen atmosphere. Amorphous silica prepared from Si(OC2H5)4 was added to Wando pyrophyllite powder in order to control the final Z value. Two different methods were applied for synthesis of $\beta$-sialon powders. In Process A, the amorphous silica prepared from Si(OC2H5)4 was admixed to Wando pyrophyllite powder. Process B was started from the mixture of Wando Y2O3 was added to the synthesized $\beta$-Sialon powders as a sintering aid, and the mixed powders were hot pressed at 175$0^{\circ}C$ for 120 min in nitrogen atmosphere under 30 MPa. Their mechanical properties were compared. The maximum values of M.O.R., hardness and KIC were 667 MPa, 16 GPa and 6.3 MN/m3/2, respectively, and they are the values obtained form $\beta$-Sialon ceramics prepared by process A of Z=0.5.

• Journal of the Korean Ceramic Society
• /
• v.27 no.6
• /
• pp.777-782
• /
• 1990

The sintering behavior of cordierite powders synthesized using a sol-gel method of metal alkoxides Si(OC2H5)4, Al(OC3H71)3 and Mg(OC2H5)2 was investigated. Densification of the powder compacts fabricated using the precursor powders calcined at 900$^{\circ}C$ for 2hrs was improved over the sintering temperature range of 800 to 980$^{\circ}C$. The powder compacts, fabricated using the calcined precursor powders and sintered at 1300$^{\circ}C$ for 2hrs, showed relative density of 97-98%, 3-point bending strength of 120-140Mpa, KIC of 2.4-3.7 Mpam1/2, and thermal expansion coefficient of 1.48-1.66${\times}$10-6/$^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.450-451
• /
• 2008

Amorphous silicon Solar cell has n-i-p structure in general, and each layer's thickness and doping concentration are very important factors which are as influential on efficiency of salar cell. Using AFORS HET simulation to get the high efficiency, by adjusting n layer's thickness and doping concentration, p layer's doping concentration. The optimized values are a-Si:H(n)'s thickness of 1nm, a-Si:H(n)r's doping concentration of $2\times10^{20}cm^{-3}$, a-Si:H(p+)r's doping concentration of $1\times10^{19}cm^{-3}$. After optimization, the solar cell shows $V_{oc}$=679.5mV, $J_{sc}$=39.02mA/$cm^2$, FF=83.71%, and a high Efficiency=22.21%. Though this study, we can use this study for planning or manufacturing solar cell which has high efficiency.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.6
• /
• pp.30-37
• /
• 1989

The PIN type a-SiC:H/a-Si:H heterojunction solar cells were fabricated by using the rf glow discharge decomposition of $SiH_4$ mixed with $CH_4,B_2,H_6\;and\;PH_3.$ The efficiency of the solar cell of the $SnO_2/ITO$ was higher than that of ITO transparent oxide layer by 1.5%. The P layer was prepared with the thickness of $100{\AA}$ and $CH_4/SiH_4$ ration of 5. The I layer has been deposited on the P layer and it is not pure intrinsic but near N type. So $SiH_4$ mixed with $B_2H_6$ of 0.3ppm was used to change this N type nature to intrinsic having the thickness of 5000${\AA}$. And consecutively, the N layer was deposited with t ethickness of $400{\AA}$ using $SiH_4/PH_3$ mixtures. The solar cell demonstrated 0.94V of $V_{oc'}$ 14.6mA/cm of $J_{sc}$ and 58.2% of FF, resulting the efficiency of 8.0%. To minimize loss by the reflection of light, $MgF_2$ layer was coated on the lgass and the efficiency was improved by 0.5%. Therefore, the solar cell indicated overall efficiency of 8.5%.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.10
• /
• pp.1694-1696
• /
• 2016

Present thin film solar cells with hydrogenated amorphous silicon oxide (a-SiO:H) as an absorber suffer from low fill factor(FF) of 61~64 [%] in spite of its benefits related to high open circuit voltage ($V_{oc}$). Since degraded quality of a-SiO:H absorber by alloying with oxygen can affect the FF, we aimed to achieve high photosensitivity by minimizing $CO_2$ gas addition. Improving optical gap($E_{opt}$) has been attained by strong hydrogen dilution combined with lowering substrate temperature down to 100 [$^{\circ}C$]. Small amount of the $CO_2$ was added in order to disturb microcrystalline formation by high hydrogen dilution. The developed a-SiO:H has high photosensitivity (${\sim}2{\times}10^5$) and high $E_{opt}$ of 1.85 [eV], which contributed to attain remarkable FF of 74 [%] and high $V_{oc}$ (>1 [V]). As a result, high power conversion efficiency of 7.18 [%] was demonstrated by using very thin absorber layer of only 100 [nm], even though we processed all experiment at extremely low temperature of 100 [$^{\circ}C$].

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.487-488
• /
• 2008

SiOC films containing alkyl groups have a low dielectric constant because of the interaction between the C-H hydrogen bonds and the oxygen of high electro-negative atom. The Si-$CH_3$ in a void is broken by the $O_2$, therefore the strength of CH bond in Si-O-O-$CH_3$ bond increases. The Si-O-O-$CH_3$ bond is broken by nucleophilic attack due to Si atom, again. The elongation of C-H bond causes the red shift, and the compression of C-H bond causes the blue shift. Among these chemical shifts, the blue shift from $1000\;cm^{-1}$ to $1250\;cm^{-1}$ was related with the formation of pores. If the oxygen is deficient condition, the methylradicals of the electron-rich substitution group terminate easily the Si-O-Si cross-link, and the pore is originated from the cross-link breakdown due to much methyl radicals of Si-$CH_3$. The dielectric constant of the films decreases due to pore generation.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2007.08a
• /
• pp.261-261
• /
• 2007

• Membrane Journal
• /
• v.14 no.4
• /
• pp.312-319
• /
• 2004

The porous SiO$_2$-B$_2$O$_3$ membrane was prepared from Si(OC$_2$$H_5$)$_4$-($CH_3$O)$_3$B-C$_2$$H_5$OH-$H_2O$ system by sol-gel method. In order to investigate the characteristics of this membrane, we examined that using BET, IR spectrophotometer, X-ray diffractometer, SEM and TEM. At $700^{\circ}C$, the surface area of SiO$_2$-B$_2$O$_3$ membrane was 354.398 $m^2$/, the median pore diameter was 0.0048 ${\mu}{\textrm}{m}$, and the particle size of SiO$_2$-B$_2$O$_3$ membrane was 7 nm. The separation properties of the gas mixture ($H_2$/$N_2$) through the SiO$_2$-B$_2$O$_3$ membrane was studied as a function of pressure. The real separation factor($\alpha$) of SiO$_2$-B$_2$O$_3$ membrane for $H_2$/$N_2$ gas mixture was 4.68 at 155.15 cmHg and $25^{\circ}C$. The real separation factor($\alpha$), head separation factor($\beta$) and tail separation factor((equation omitted)) were increased as the pressure of permeation cell increased.