• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.743-744
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.499-500
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.497-498
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.421-422
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• 2009

• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.11a
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• pp.18-21
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• 2005

• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.11a
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• pp.11-16
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.9-10
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• 2010

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.456-456
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• 2009

Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. 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, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

• Korean Journal of Optics and Photonics
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• v.23 no.3
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• pp.124-127
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• 2012

We designed and fabricated dichroic filters for high-power fiber lasers to protect the pumping laser diode from counterpropagating laser beams. The transmittance at laser diode wavelengths of 905 nm~925 nm was designed to be less than 0.1% and the transmittance at the fiber laser or Brillouin scattering wavelengths of 1020 nm ~ 1100 nm was designed to be more than 99.9%. Since oxide materials have good adhesion to the $SiO_2$ substrate, $SiO_2/Ta_2O_5$ were used as coating materials. The filter was fabricated according to our optimized design and its characteristics were compared with the theoretical design. As a result, the transmittance at laser diode wavelengths of 905 nm~925 nm was measured to be less than 0.1%, and the transmittance at the fiber laser or Brillouin scattering wavelengths of 1020 nm~1100 nm was measured to be more than 95.5%, which coincided well with the theoretical design considering processing errors. The filter was found to operate well over 1W of input laser power.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.1-12
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• 2006

The purpose of this study were to evaluate the efficacy of the newly developed Digital Imaging Fiber-Optic Trans-illumination (DIFOTI) system in detecting carious lesions in vivo as gold standard with confocal laser scanning microscopy and compared the efficacy of traditional radiography and DIFOTI system in vito as gold standard with confocal laser scanning microscopy, too. For the in vivo study, the subject pool consisted of 23 grammar school age patients just prior to entering the mixed dentition phase Each patient was given a DIFOTI examination of the anterior and posterior teeth. During $6{\sim}8$ months, the naturally expire primary teeth were collected and the efficacy of DIFOTI system was compared with confocal laser scanning microscopy. For in vitro study, 40 primary teeth were collected and decalcified by Carbopol decalcification solution for 1, 2, 4 and 8 days. Every experiment period, all teeth were DIFOTI examined and sectioned to take an image of confocal laser scanning microscopy Sensitivity and specificity were calculated from the result of DIFOTI examine and confocal laser scanning microscopy analysis. The results are as follows : 1. From the in vivo study, the sensitivity of DIFOTI examine was 0. 61 and specificity was 0.63. 2. From the in vivo study, the sensitivity of DIFOTI examine was 0.71 and specificity was 0.75.