• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.80-86
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• 2017

In this study, nitrogen functional groups were introduced on graphite fiber (GF) to modify their electrical properties, and heating properties were investigated according to the treatment conditions. GF was prepared by a thermal solid-state reaction at $200^{\circ}C$ for 2 h. Surface properties of the nitrogen doped GF were examined by XPS, and its resistance and heating temperature were measured using a programmable electrometer and thermo-graphic camera, respectively. The XPS result showed that the nitrogen functional groups on the GF surface were increased with increasing of urea contents, and the heating property of the GF was also improved as nitrogen functional groups were introduced. The maximum heating temperature of GF treated by urea was $53.8^{\circ}C$ at 60 V, which showed 55% improved heating characteristics compared to that of non-treated GF. We ascribe this effect to introduced nitrogen functional groups on the GF surface by thermal solid-state reaction, which significantly affects the heating characteristics of GF.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.401-401
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• 2011

태양전지 제작에 있어서 에미터층의 최적화를 위해 POCl 도핑시 에미터층의 면저항 가변에 중요한 파라미터인 온도와 가스비를 변화하여 실험을 진행하였다. 본 실험에 사용될 최초 기판은 두께가 200${\pm}$5 ${\mu}m$, 비저항이 0.5~0.3 ${\Omega}{\cdot}cm$의 P-type(100) 실리콘 기판을 사용하였으며 먼저 POCl3양과 deposition 시간 그리고 산소와 질소의 양을 고정시키고 온도에 따른 에미터 면저항 변화를 알아보았다. 온도는 830, 840, 850, 860, 870, 880$^{\circ}C$로 가변시켰으며 공정온도가 높아질수록 면저항 값이 낮아짐을 알 수 있었다. 균일도는 낮은 온도에서는 다소 좋지 않았지만 온도가 높아질수록 점차 좋아졌으며 870$^{\circ}C$ 이상에서는 거의 균일한 값을 얻을 수 있었다. 한편, 이번에는 공정온도를 고정하고 산소와 POCl3 가스량의 변화에 따른 면저항 특성과 균일도를 알아보았다. 가스비와 압력 그리고 위치별 면저항 특성에 대해서 알아보았고 부분압이 증가함으로 반응로 내의 O2의 양이 증가함을 알 수 있었다. 증가한 O2는 도핑과정에서 산화막을 더 두껍게 형성하게 하며 높은 면저항 값을 가져오게 하였다. 즉, 충분한 가스량의 주입으로 도핑시 균일도를 향상시킬 수 있었다. 이와 같이 부분압이 증가함에 따라 면저항의 증가와 균일도의 향상을 가져왔다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.48.2-48.2
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• 2010

고효율 실리콘 태양전지 개발은 단파장의 광 응답 특성 개선을 위한 선택적 에미터 형성과 반사 손실 개선을 위한 미세 패턴 전극을 형성하는데 집중적인 연구가 진행되고 있다. 본 실험에서는 레이저 도핑된 선택적 에미터 위에 미세 패턴 Ni/Cu 도금 전극을 형성하였다. 니켈과 동 도금은 무전해 Light induced plating(LIP)으로 진행하였다. 니켈 도금 전극의 접착력 개선과 접촉저항 개선을 위해서 니켈 전극을 질소 분위기에서 열처리하여 니켈실리사이드(NiSi)를 형성하였다. 니켈 도금 두께와 니켈실리사이드 열처리 조건을 최적화하여 충실도 77.4%, 변환효율 18.5%를 달성하였다.

• Electrical & Electronic Materials
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• v.7 no.3
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• pp.206-212
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• 1994

In this paper, We discuss the $POCI_3$ doping process according to the variation of deposition temperature, gas flow rate and doping time. The factors acted with $POCI_3$ doping are gas flow rate deposition temperature and time etc. Among them the temperature is the most important factor. For the $POCI_3$ flow rate, it should not exceed the resistivity saturation point developed on poly surface by annealing treatment. Therefore, this study suggests the optimum conditions of Poly-silicon treatments with the $POCI_3$ flow rate.

• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.163-168
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• 2015

Graphene has attracted much attention due to its remarkable physical properties and potential applications in many fields. In special, the electronic properties of graphene are influenced by the number of layer, stacking sequence, edge state, and doping of foreign elements. Recently, many efforts have been dedicated to alter the electronic properties by doping of various species, such as hydrogen, oxygen, nitrogen, ammonia and etc. Here, we report our recent results of plasma doping on graphene. We prepared mechanically exfoliated graphene, and performed the plasma treatment using ammonia gas for nitrogen doping. The direct-current plasma system was used for plasma ignition. The doping level was estimated from the number of peak shift of G-band in Raman spectra. The upshift of G-band was observed after ammonia plasma treatment, which implies electron doping to graphene.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.258-259
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• 2014

이산화티타늄($TiO_2$)의 띠 간격 (Band-Gap) 에너지를, 자외선 영역에서 질소와 $Ag-PbMoO_4$를 이용하여 가시광 응답형 광촉매를 제조하기 위하여 실험하였다. 이와 함께 제조한 "$AgPbMoO_4+N-TiO_2$"가 $TiO_2$, $N-TiO_2$, $PbMoO_4$, $AgPbMoO_4$에 비해 에너지 흡수 파장대의 향상을 확인하고 XRD, XPS, FE-SEM, UV-vis-DRS diffuse reflectance spectroscopy 분석을 통해 특성평가 및 분말의 광촉매 활성을 염료의 광촉매 분해반응으로 규명하였다.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.111-115
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• 2015

To improve the efficiency of the Si solar cell, high minority carrier life time is required. Therefore, the passivation technology is important to eliminate point defects on the silicon surface, causing the loss of minority carrier recombination. PECVD or post-annealing of thermally-grown $SiO_2$ is commonly used to form the passivation layer, but a high-temperature process and low thermal stability is a critical factor of low minority carrier lifetime. In this study, atomic layer deposition was used to grow the $Al_2O_3$ passivation layer at low temperature process. $Al_2O_3$ was selected as a passivation layer which has a low surface recombination velocity because of the fixed charge density. For the high charge density, an improved minority carrier lifetime, and a low surface recombination, nitrogen was doped in the $Al_2O_3$ thin film and the improvement of passivation was studied.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.119-125
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• 2011

N-doped Titanium oxides were prepared by using urea as a source of nitrogen. The photoactivities of the doped $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, ultraviolet lamp, fluorescent lamp and solar light. XRD analysis was conducted to identify the crystal structure of the synthesized photocatalysts. N-doped $TiO_2$ and $pure-TiO_2$ was anatase type. SEM results showed that spherical particles were formed, which are the characteristics of the anatase form. N doped $TiO_2$ showed higher $UV_{254}$ decrease ratio and DOC removal ratio compared to $pure-TiO_2$. The humic acid degradation reaction using the UV-A lamp and UV-C lamp was assigned to pseudo-first order reaction. For solar light, only $pure-TiO_2$ and $N-TiO_2$ exhibited the pseudo-first order reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.70-70
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• 2009

Si 도핑한 $Ge_2Sb_2Te_5$ 박막은 비정질상에서의 열적 안정성증가, fcc에서 hex상으로의 상전이 억제, 활성화 에너지 증가 등의 특성을 보인다. 본 연구에서는 Si 도핑에 의한 $Ge_2Sb_2Te_5$ 박막의 전기적 그리고 구조적인 특성에 관한 실험을 진행하였다. 실험에 사용된 Si 도핑 $Ge_2Sb_2Te_5$ 박막은 Si 기판 위에 radio frequency power supply를 사용해 Si과 $Ge_2Sb_2Te_5$ 타겟을 co-sputtering하여 증착하였다. Si의 sputtering 파워를 달리하여 실리콘의 농도를 다르게 증착 하였고 X-ray photoelectron spectroscopy (XPS)를 사용하여 박막의 Si 농도를 측정하였다. 증착된 박막은 질소 분위기 하에서 $5\;^{\circ}C$/min으로 열처리 하여 여러 온도와 Si 농도에서의 박막의 특성을 측정하였다. 열처리 전, 후의 박막은 X-ray diffraction (XRD) 분석을 통하여 각각의 온도에서의 구조적 특성을 분석하였다. 열처리 온도에 따르는 필름의 전기적 특성 파악을 위해서 four-point probe를 이용하여 박막의 면저항을 측정하였고 그 값은 3 회 이상 측정하여 평균값을 사용하였다. Nano-pulse scanner를 사용하여 다양한 파워범위와 펄스폭 범위에서의 박막의 상변화에 따른 반사도 차이를 측정하여 각 조성에서의 비정질-결정질상 변화속도를 분석하였다.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.169-174
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• 2015

In this research, pristine graphene was synthesized using methane ($CH_4$) gas, and N-doped graphene was synthesized using pyridine ($C_5H_5N$) liquid source by chemical vapor deposition (CVD) method. Basic optical properties of both pristine and N-doped graphene were investigated by Raman spectroscopy and XPS (X-ray photoemission spectroscopy), and electrical transport characteristics were estimated by current-voltage response of graphene channel as a function of gate voltages. Results for CVD grown pristine graphene from methane gas show that G-peak, 2D-peak and C1s-peak in Raman spectra and XPS. Charge neutral point (CNP; Dirac-point) appeared at about +4 V gate bias in electrical characterization. In the case of pyridine based CVD grown N-doped graphene, D-peak, G-peak, weak 2D-peak were observed in Raman spectra and C1s-peak and slight N1s-peak in XPS. CNP appeared at -96 V gate bias in electrical characterization. These result show successful control of the property of graphene artificially synthesized by CVD method.