• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.6
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• pp.473-479
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• 2011

In this paper, we have compared amorphous InGaZnO (a-IGZO) thin-film transistor (TFT) with the nano-crystalline embedded-IGZO ($N_c$-embedded-IGZO) TFT fabricated by solid-phase crystallization (SPC) technique. The field effect mobility (${\mu}_{FE}$) of $N_c$-embedded-IGZO TFT was 2.37 $cm^2/Vs$ and the subthreshold slope (S-factor) was 0.83 V/decade, which showed lower performance than those of a-IGZO TFT (${\mu}_{FE}$ of a-IGZO was 9.67 $cm^2/Vs$ and S-factor was 0.19 V/decade). This results originated from generation of oxygen vacancies in oxide semiconductor and interface between gate insulator and semiconductor due to high temperature annealing process. However, the threshold voltage shift (${\Delta}V_{TH}$) of $N_c$-embedded-IGZO TFT was 0.5 V, which showed 1 V less shift than that of a-IGZO TFT under constant current stress during $10^5$ s. This was because there were additionally less increase of interface trap charges in Nc-embedded-IGZO TFT than a-IGZO TFT.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.198-198
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• 2010

산화물 반도체는 넓은 밴드갭을 가지고 있어 가시광에서 투명하며 높은 이동도로 디스플레이 구동 회로 집적에 유리하다. 또한 가격 및 공정 측면에서도 기존의 Si 기판 소자에 비해 여러 장점을 가지고 있어 차세대 디스플레이의 핵심 기술로 산화물반도체에 대한 관심이 높아지고 있다. 본 연구는 RF 동시 스퍼터링법을 이용하여 Zn-Sn-O 박막을 제조하고, 그 전기적, 광학적, 구조적 특성에 대해 조사하였다. 일정한 증착 온도($100^{\circ}C$)에서 ZnO와 $SnO_2$ 타켓의 인가 파워를 조절하여 Sn/(Zn+Sn) 성분비가 약 40~85%인 Zn-Sn-O 박막을 제조하였다. Sn 함량이 증가할수록 박막의 비저항은 약 $2{\times}10^{-1}$ (Sn 45%)에서 약 $2\;{\times}\;10^{-2}\;{\Omega}{\cdot}cm$ (Sn 67%)까지 감소하다가 다시 증가하는 경향을 보였다. 이 때 캐리어 농도는 $3\;{\times}\;10^{18}$에서 $4\;{\times}\;10^{19}\;cm^{-3}$으로 증가하였으며, 이동도는 11에서 $8\;cm^2/V{\cdot}s$로 약간 감소하였다. XRD분석결과, 제조된 모든 Zn-Sn-O 박막은 비정질 구조를 가짐을 확인하였다. 투과율은 박막 내 Sn함량 증가에 따라 감소하나 모든 시편이 약 70%이상의 투과도를 나타내었다. Zn-Sn-O 박막의 Ga 도핑 영향을 확인하기 위해 ZnO 타켓 대신 갈륨이 5.7 wt.% 도핑된 GZO 타켓을 사용하여 동일한 공정조건에서 박막을 제조하였다. Ga이 첨가된 Zn-Sn-O 박막은 구조적 특성과 광학적 특성에서는 큰 차이를 보이지 않았으나, 전기적 특성의 뚜렷한 변화가 관찰되었다. Sn 함량이 45%인 Zn-Sn-O 박막의 경우, 캐리어 농도가 $3.1\;{\times}\;10^{18}$에서 Ga 도핑 효과로 인해 $1.7\;{\times}\;10^{17}\;cm^{-3}$으로 크게 감소하고 이동도는 11에서 $20\;cm^2/V{\cdot}s$로 증가하였다. 따라서 본 연구는 Zn-Sn-O 비정질 박막에 Ga을 도핑함으로써 산화물 반도체재료로서 요구되는 물성을 만족시킬 수 있다는 가능성을 제시하였다.

• (The) Research of the performance art and culture
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• no.39
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• pp.31-67
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• 2019

This thesis examines the difficulties of utilizing the narrative and music of Pansori: 판소리 in Changguk: 창극. For this examination, I consider that the reason for the difficulty of making Changguk is the difference between Pansori and Changguk as the genres. Most of the Changguk based on the traditional five Pansori works perform the narration and songs of Pansori literally. However, the original narrative of Pansori has a distinctive dual structure since the formation of its first and second half is created separately. As the drama genre visualizes the story and emphasizes the consistency of action, unlike Pansori, the duality of the original narrative can be seen as the inconsistency of the action. In addition, since the sounds of the original Pansori are rather explanatory than dramatic even in the climax scenes of Jeokbyeok battlefields, it is difficult to produce dramatic scenes in Changguk. The voices of the military, not in the original works, play important roles in revealing the hidden theme effectively in Changguk. However It is impossible to relocate the original text of Pansori into Changguk, as even the voices of the military lack verisimilitude in terms of narrative. Changguk can only be developed as its own work by actively researching and dismantling Pansori .

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.701-706
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• 2013

We have focused on the conversion efficiency of CIGS thin film solar cell prepared by co-evaporation method as well as the optimization of process condition. The total thickness of back electrode was fixed at 1 ${\mu}m$ and the structural, electric and optical properties of CIGS thin film were investigated by varying the thickness of Mo:Na bottom layer from 0 to 500 nm. From the experimental results, the content of Na was appeared as 0.28 atomic percent when the thickness of Mo:Na layer was 300 nm with compactly densified plate-shape surface morphology. From the XRD measurements, (112) plane was the strongest preferential orientation together with secondary (220) and (204) planes affecting to the crystallization. The lowest roughness and resistivity were 2.67 nm and 3.9 ${\Omega}{\cdot}cm$, respectively. In addition, very high carrier density and hole mobility were recorded. From the optimization of Mo:Na layer, we have achieved the conversion efficiency of 9.59 percent.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.63-67
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• 1998

The synthesis and characterization of the monomeric group 13 heterocyclic thiosemicarbazone complexes $Me_2M[SC_4H_3CHNNC(S)SCH_3]$ (M=Al (2), Ga (3)) are described. Compounds 2-3 were prepared using $MMe_3$ (M=Al, Ga) in toluene with 2-thiophenecarboxaldehyde-S-methyldithiocarbazat e under anaerobic conditions. These complexes have been characterized by $^1H\;NMR,\; ^{13}C\; NMR$, elemental analyses, and single-crystal X-ray diffraction. 2 crystallizes in the monoclinic space group $P2_1/c$ with unit cell parameters a=10.2930(5) Å, b=18.564 (1) Å, c=7.3812(6) Å, V=1347.9(2) Å3, $D_{calc}=1.342\; gcm^{-3}$ for Z=4, 9281 reflections with $I_o<3{\sigma}\;(I_o),$ R1=0.0500 and wR2=0.0526. 3 crystalizes in the orthorhombic space group $P_{bca}$ with unit cell parameters a=13.340(3) Å, b=19.9070(5) Å, c=11.3690(2) Å, $V=2673.88(9)\;{\AA}^3$, $D_{calc}=1.511\; gcm^{-3}$ for Z=8, 17004 reflections with $I_o>3{\sigma}\;(I_o),$, R1=0.0480 and wR2=0.0524. Compound 3 is a monomeric gallium compound with a weak interaction between the pendant thiophene and the gallium center.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.444-447
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• 2019

It was proven that the light outputs of blue GaN-based light-emitting diodes (LEDs) was seriously influenced by the application of external stress. We have simulated the wave function overlap of an electron and hole, which are significantly reduced by the development of stress. Consequently, its internal quantum efficiency decreased from 67.0% to 37.5%. To experimentally investigate the effect of stress, we designed and prepared a special zig system. By applying external tensile stress to compensate for the compressive stress innately developed in Blue LEDs, it was found that the optical output was greatly enhanced from 83.1 mcd to 117.2 mcd at a current of 100 mA, an increase of approximately 41%. In contrast, when the compressive stress is developed more by external compressive stress, we observed that the light output power was reduced from 89.0 mcd to 80.7 mcd, a decrease of approximately 9.3%.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.164-165
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• 2001

애벌란치형 광검출기(Avalanche Photodiode; APD)는 내부 이득을 갖고 있어 수신감도가 좋고 고속 동작이 가능하여 광통신에 있어서 매우 중요한 소자이다. 초기에는 공정의 용이성 등으로 인해 Ge을 소재로 하는 APD가 많이 사용되었으나 1.55 $\mu\textrm{m}$ 파장에서 광흡수 특성이 좋지 않고 전자와 정공의 이온화 계수비가 거의 같아 GB Product이 낮으므로 점차 이들 특성이 우수한 InP/InGaAs APD가 사용되었다. InGaAs는 밴드갭은 Ge보다 크지만 직접천이형 밴드구조를 갖기 때문에 1.67 $\mu\textrm{m}$까지 광흡수 특성이 좋고 소수캐리어의 이동도가 높아 고속동작에 유리하다. (중략)

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.67-72
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• 2011

Recently, photovoltaic generator system is widely extended by energy policy of the government. Add to this, for high efficiency of power generation per natural light unit area is needed to sun tracking system. And it is needed to condensed light generator for reducer of equipment expense. As method of solving this problem, this paper is developed multi-flat reflector sun tracking system for sun photocell maximum power generation. The system is consisted of multi-flat reflector and two axes machinery and sun location perceiver and AVR controller. GaAs 3J cell generated 6.75 times power more than silicon cell by times condensing light system. As a result, condensing light system of multi-flat reflector generated maximum power and showed reducing costs to photovoltaic generator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.67-70
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• 2000

In this paper, all SCR recombination currents including setback and graded layer's recombination currents are analytically introduced for the first time. Different emitter-base structures are tested to prove the validity of the model. In 1995, the analytical equations of electric field, electrostatic potential, and junction capacitance for abrupt and linearly graded heterojunctions with or without a setback layer was derived. But setback layer and linearly graded layer's recombination current was considered numerically. In this paper, recombination current model included setback layer and graded layer is proposed. New recombination current model also includes abrupt heterojunction's recombination current model. In this paper, new recombination current model analytically explains effects of setback layer and graded layer.

• Journal of Korean Vacuum Science & Technology
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• v.4 no.3
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• pp.63-67
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• 2000

We have studied the photoluminescence properties of undoped epitaxial layers of GaN on sapphire substrate grown by horizontal low pressure metal organic chemical vapor deposition method in the temperature range of 9-300 K. At 9 K the spectra are dominated by the well resolved interband free excitons A and B as well as bound excitons. Temperature dependence of free exciton transitions was studied and Varshni's coefficients for the temperature variation of bandgap were determined.