• 한국세라믹학회지
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• 제30권4호
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• pp.316-324
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• 1993

Three types of dispersed, coated and mechanically mixed SiC reinforced Al2O3 composite powders were used to investigate the effect of composite powder type on sintering characteristics and properties of Al2O3-SiC composites. Sinterability of coated type composite powders was superior to that of other composite powders when they were pressureless sintered at 1500~1$700^{\circ}C$ for 2h in Ar atmosphere. However, sinterabilities (>98% TD) of each type of composite powders were similar when they were hot pressed at 180$0^{\circ}C$ for 1h under 30MPa in N2 atmosphere. SiC powders were randomly distributed in the specimen prepared from dispersed type composite powders, whereas homogeneously distributed for coated type specimens. It was found that SiC powders inhibited the grain growth of Al2O3, and fracture toughness was increased by the increment of crack growth resistance due to residual stress by secondary SiC particles within Al2O3 grains.

• Transactions on Electrical and Electronic Materials
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• 제13권4호
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• pp.192-195
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• 2012

We reported diborane ($B_2H_6$) doped wide bandgap hydrogenated amorphous silicon oxide (p-type a-SiOx:H) films prepared by using silane ($SiH_4$) hydrogen ($H_2$) and nitrous oxide ($N_2O$) in a radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) system. We improved the $E_{opt}$ and conductivity of p-type a-SiOx:H films with various $N_2O$ and $B_2H_6$ ratios and applied those films in regards to the a-Si thin film solar cells. For the single layer p-type a-SiOx:H films, we achieved an optical band gap energy ($E_{opt}$) of 1.91 and 1.99 eV, electrical conductivity of approximately $10^{-7}$ S/cm and activation energy ($E_a$) of 0.57 to 0.52 eV with various $N_2O$ and $B_2H_6$ ratios. We applied those films for the a-Si thin film solar cell and the current-voltage characteristics are as given as: $V_{oc}$ = 853 and 842 mV, $J_{sc}$ = 13.87 and 15.13 $mA/cm^2$. FF = 0.645 and 0.656 and ${\eta}$ = 7.54 and 8.36% with $B_2H_6$ ratios of 0.5 and 1% respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.214-217
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• 2006

p-type 비정질 실리콘 에미터와 n-type 실리콘 기판의 계면에 intrinsic 비정질 실리콘을 증착함으로써 계면의 재결합을 억제하여 20%가 넘는 효율을 보이는 이종접합 태양전지가 Sanyo에 의해 처음 제시된 후 intrinsic layer에 대한 연구가 많이 진행되어 왔다. 하지만 p-type wafer의 경우는 n-type에 비해 intrinsic buffer의 효과가 미미하거나 오히려 특성을 저하시킨다는 보고가 있으며 그 이유로는 minority carrier에 대한 barrier가 상대적으로 낮다는 것과 partial epitaxy가 발생하기 때문으로 알려져 있다. 본 연구에서는 partial epitaxy를 억제하기 위한 방법으로 증착 온도를 낮추고 QSSPC를 사용하여 minority carrier lifetime을 측정함으로써 각 온도에 따른 passivation 특성을 평가하였다. 또한 SiH4에 H2를 섞어서 증착하였을 경우 각 dilution ratio(H2 flow/SiH4 flow)에서의 passivation 특성 또한 평가하였다. 기판 온도 $100^{\circ}C$에서 증착된 샘플의 lifetime이 가장 길었으며 그 이하와 이상에서는 lifetime이 감소하는 경향을 보였다 낮은 온도에서는 박막 자체의 결함이 증가하였기 때문이며 높은 온도에서는 partial epitaxy의 영향으로 추정된다. H2 dilution을 하여 증착한 샘플의 경우 SiH4만 가지고 증착한 샘플보다 훨씬 높은 lifetime을 가졌다 이 또한 박막 FT-IR결과로부터 H2 dilution을 한 경우 compact한 박막이 형성되는 것을 확인할 수 있었는데 radical mobility 증가에 의한 박막 특성 향상이 원인으로 생각된다.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.487-490
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• 2010

This paper describes the elecrtical and optical characteristics of $N_2$ doped porous 3C-SiC films. Polycrystalline 3C-SiC thin films are anodized by $HF+C_2H_5OH$ solution with UV-LED exposure. The growth of in-situ doped 3C-SiC thin films on p-type Si (100) wafers is carried out by using APCVD (atmospheric pressure chemical vapor deposition) with a single-precursor of HMDS (hexamethyildisilane: $Si_2(CH_3)_6)$. 0 ~ 40 sccm $N_2$ was used for doping. After the growth of doped 3C-SiC, porous 3C-SiC is formed by anodization with $7.1\;mA/cm^2$ current density for anodization time of 60 sec. The average pore diameter is about 30 nm, and etched area is increased with $N_2$ doping rate. These results are attributed to the decrease of crystallinity by $N_2$ doping. Mobility is dramatically decreased in porous 3C-SiC. The band gaps of polycrystalline 3C-SiC films and doped porous 3C-SiC are 2.5 eV and 2.7 eV, respectively.

• 대한전자공학회논문지
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• 제26권11호
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• pp.1686-1690
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• 1989

Using the anisotropic etching characteristics of N2H4-H2O solutions, Si diaphragm was fabricated for the integrated sensors. The optimal composition and temperature of the etching solution in (100) Si etching process was established to be 50mol% N2H4 in H2O at 105\ulcorner\ulcorner for both higher etch rate (=2.6\ulcorner/min) and better surface quality of etched (100) planes. Based on the above optimal etching condition, the electrochemical etch-stop technique was employed to form n-type Si diaphragm having a thickness of 20\ulcorner and the thickness of diapragm could exactly be controlled to 20\ulcorner\ulcorner.

• 한국세라믹학회지
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• 제50권4호
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• pp.280-287
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• 2013

Plate-type phosphor is a promising substitute in overcoming the issues related to the powder phosphor paste mixed with resin. In this research, $Ca-{\alpha}-SiAlON:Eu^{2+}$ plate phosphor ($Ca_xSi_{12-(m+n)}Al_{m+n}O_nN_{16-n}:Eu_y$) was investigated for the varied compositions (m,n) of the host crystal with the fixed Eu content (y). Densification was promoted for the compositions with increasing 'm' values for the m=2n relationship. Dictated by the Eu concentration inside the phosphor crystal, photoluminescence intensity was stronger in ${\alpha}2$ specimen (m = 3.0, n = 1.5) containing the second phases when compared to ${\alpha}1$ specimen (m = 1.5, n = 0.75) comprising a single-phase ${\alpha}$-SiAlON. The concentration of Eu in the non-emitting amorphous interfacial glass phase was 2~4 times of the designed Eu concentration inside the ${\alpha}$-SiAlON crystal.

• 한국재료학회지
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• 제14권5호
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• pp.358-362
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• 2004

$Si_3$$N_4$ ceramics have been identified as one of the promising structural ceramics. This study has been carried out to investigate of the synthetic behaviors of $Si_3$$N_4$ derived from domestic silica-stone by direct nitriding method. The silicon nitridation reaction has been studied in the temperature range of $1300～1550^{\circ}C$. Below the $1400^{\circ}C$, the nitriding rate was measured to be 16%. For the temperatures higher than the $1400^{\circ}C$, $\beta$-$Si_3$$N_4$ phase was formed mainly, and the nitriding rate showed above 98%. With the increasing of sample weight of silicon powder, the nitriding rate and $\beta$-$Si_3$$N_4$ phase increased at $1400^{\circ}C$ for 2 hours. The shape and particle size of$ Si_3$$N_4$ powder synthesized at $1400^{\circ}C$ for 2 hours showed the irregular angular-type and 10 $\mu\textrm{m}$, respectively.

• 한국광학회지
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• 제3권4호
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• pp.244-251
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• 1992

$SiO_{2}$를 덮개층으로하는 $Si_{3}N_{4}$ rib 도파로의 $Si_{3}N_{4}-SiO_{2}$ 계면에 브래그격자를 제작하여 매립된 형태의 단일모우드 브래그필터 도파로를 설계하고 제작하였다. HF 완충용액을 사용하여 $Si_{3}N_{4}$ 코어층에 브래그격자를 식각하였으며 1nm까지 식각깊이를 제어하며 균일하게 식각할 수 있었다. 이러한 매립된 형태의 브래그필터는 그 특성이 소자표면의 오염에 영향을 받지 않는다. 브래그필터의 파장스펙트럼 측정에서 도파로의 모우드굴절률과 반사대역폭을 결정하고 이를 계산과 비교하여 논의하였다. 브래그필터의 도파코어층에 미세히터와 silicone rubber의 덮개층을 올려 필터파장을 가면할 수 있는 도파로 가변 필터소자를 제작하였다. 그 결과 브래그파장은 전류의 제곱에 비례하여 단파장 쪽으로 이동하였으며, 이동량은 10mA의 전류에 대해 0.41nm이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.131-131
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• 2008

Silicon carbide (SiC) has attracted significant attention for high frequency, high temperature and high power devices due to its superior properties such as the large band gap, high breakdown electric field, high saturation velocity and high thermal conductivity. We performed Al ion implantation processes on n-type 4H-SiC substrate using a SILVACO ATHENA numerical simulator. The ion implantation model used a Monte-Carlo method. We studied the effect of channeling by Al implantation simulation in both 0 off-axis and 8 off-axis n-type 4H-SiC substrate. We have investigated the Al distribution in 4H-SiC through the variation of the implantation energies and the corresponding ratio of the doses. The implantation energies controlled 40, 60, 80, 100 and 120 keV and the implantation doses varied from $2\times10^{14}$ to $1\times10^{15}cm^{-2}$. In the simulation results, the Al ion distribution was deeper as increasing implantation energy and the doping level increased as increasing implantation doses. After the post-implantation annealing, the electrical properties of Al-implanted p-n junction diode were investigated by SILV ACO ATLAS numerical simulator.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.322-322
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• 2010

For boron doping on n-type silicon wafer, around $1,000^{\circ}C$ doping temperature is required, because of the relatively low solubility of boron in a crystalline silicon comparing to the phosphorus case. Boron doping by fiber laser annealing and lamp furnace heat treatment were carried out for the uniformly deposited p-a-Si:H layer. Since the uniformly deposited p-a-Si:H layer by cluster is highly needed to be doped with high temperature heat treatment. Amorphous silicon layer absorption range for fiber laser did not match well to be directly annealed. To improve the annealing effect, we introduce additional lamp furnace heat treatment. For p-a-Si:H layer with the ratio of $SiH_4:B_2H_6:H_2$=30:30:120, at $200^{\circ}C$, 50 W power, 0.2 Torr for 30 min. $20\;mm\;{\times}\;20\;mm$ size fiber laser cut wafers were activated by Q-switched fiber laser (1,064 nm) with different sets of power levels and periods, and for the lamp furnace annealing, $980^{\circ}C$ for 30 min heat treatment were implemented. To make the sheet resistance expectable and uniform as important processes for the $p^+$ layer on a polished n-type silicon wafer of (100) plane, the Q-switched fiber laser used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the fiber laser treatment showed the trade-offs between the lifetime and the sheet resistance as $100\;{\omega}/sq.$ and $11.8\;{\mu}s$ vs. $17\;{\omega}/sq.$ and $8.2\;{\mu}s$. Diode level device was made to confirm the electrical properties of these experimental results by measuring C-V(-F), I-V(-T) characteristics. Uniform and expectable boron heavy doped layers by fiber laser and lamp furnace are not only basic and essential conditions for the n-type crystalline silicon solar cell fabrication processes, but also the controllable doping concentration and depth can be established according to the deposition conditions of layers.