• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.309-309
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• 2013

기존의 CIGS 태양전지는 window 층(GZO/ZnO/CdS)에서의 투과 및 반사 손실을 줄이기 위하여 MgF2를 이용한 AR (Anti Reflection) 층을 적용하여 cell을 제작하고 있다. 현재 단위공정을 줄이고 시간적 경제적 비용을 절감하기위해 무반사 코팅층 없이 표면의 구조를 변화 시키거나 CIGS 태양전지의 window 층만으로 cell 구조에 적용하는 연구가 많이 진행되고 있다. 본 연구는 AR층과 window층 역할을 동시에 만족하는 일체화된 window층 두께를 설계하고 성장한 후, window층의 열처리 전후의 구조적, 광학적 및 전기적 특성을 비교 평가하였다. Macleod simulation을 이용하여 window 층을 설계한 후, RF magnetron sputtering법을 이용하여 상온성장 시킨 후 N2 분위기에서 후열처리 조건에 따른 박막의 구조적, 전기적 및 광학적 특성을 변화를 X-ray diffractometer, Field emission-scanning electron microscope, Atomic force microscopy, 4 point probe, Hall 측정, 투과도 및 반사도등으로 비교 평가하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.313-314
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• 2007

Ga-doped ZnO(GZO) multilayer coatings were prepared on glass by DC sputtering. Optimization of the deposition conditions of both AZO and Au layers were performed for better electrical and optical characteristics. The properties of multilayer were affected by the deposition process of both GZO and Au layers. The best multilayer coating exhibits low resistivity of $2.72{\times}10^{-3}\;{\Omega}-cm$ and transmittance of 77%. From these results, we can confirm a possibility of the application as transparent conductive electrodes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.114-120
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• 2012

In this research, we prepared Ga doped zinc oxide(ZnO:Ga, GZO) targets each difference sintering temperature $700^{\circ}C$, $800^{\circ}C$, and doping rate 1 wt.%, 2 wt.%, 3 wt.%. The characteristics of thin film on glass substrates which deposited by facing target sputtering in pure Ar atmosphere are reported. Ga doped zinc oxide film is attracted material through low resistivity, high transmittance, etc. When prepared target powder's structure was investigated by scanning electron microscope, densification and coarsening by driving force was observed. For each ZnO:Ga films with a $Ga_2O_3$ content of 3 wt.% at input power of 45W, the lowest resistivity of $9.967{\times}10^{-4}{\Omega}{\cdot}cm$ ($700^{\circ}C$) and $9.846{\times}10^{-4}{\Omega}{\cdot}cm$ ($800^{\circ}C$) was obtained. the carrier concentration and mobility were $4.09{\times}10^{20}cm^{-3}$($700^{\circ}C$), $4.12{\times}10^{20}cm^{-3}$($800^{\circ}C$) and $15.31cm^2/V{\cdot}s(700^{\circ}C)$, $12.51cm^2/V{\cdot}s(800^{\circ}C)$, respectively. And except 1 wt.% Ga doped ZnO thin film, average transmittance of these samples in the range 350-800 nm was over 80%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.5
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• pp.374-378
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• 2010

The effects of $O_2$ plasma pretreatment on the properties of Ga-doped ZnO films on polyimide substrate were studied. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion between the polyimide substrate and the GZO film, $O_2$ plasma pretreatment process was used prior to GZO sputtering. As the RF power and the treatment time increased, the crystallinity increased and the contact angle decreased significantly. When the RF power was 100 W and the treatment time was 120 sec, the resistivity of GZO films on the polyimide substrate was $1.90{\times}10^{-3}{\Omega}-cm$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.5
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• pp.385-390
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• 2013

$(Ga_2O_3)_x(ZnO)_{100-x}$ (GZO) films were prepared at room temperature by using a facing target sputtering (FTS) system and their electrical resistivites was investigated as a function of the $Ga_2O_3$ content. The GZO film with an atomic ratio of $Ga_2O_3$ of x= 7 wt.%, shows the lowest resistivity of $7.5{\times}10^{-4}{\Omega}{\cdot}cm$. The GZO films were also prepared at various substrate temperatures from room temperature to $300^{\circ}C$, and their electrical resistivity was found to be improved as the substrate temperature was increased, A very low resistivity of $2.8{\times}10^{-4}{\Omega}{\cdot}cm$ that is almost comparable with that of ITO film was obtained in the GZO films prepared at the substrate temperature of $300^{\circ}C$ by using the FTS.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.303-308
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• 2011

The Gallium-doped ZnO(GZO) film deposited at a temperature of $200^{\circ}C$ and a pressure of 10 mtorr has an optical transmittance of 89.0% and a resistivity of $2.0\;m{\Omega}{\cdot}cm$ because of its high crystallinity. Effect of $Al_2O_3$ oxide buffer layers on the optical and electrical properties of sputtered ZnO films were intensively investigated for developing the electrodes of opto-electronic devices which demanded high optical transmittance and low resistivity. The use of $Al_2O_3$ buffer layer could increase optical transmittance of GZO film to 90.7% at a wavelength of 550 nm by controlling optical spectrum. Resistivity of deposited GZO films were much dependent on the deposition condition of $O_2/(Ar+O_2)$ flow rate ratio during the buffer layer deposition. It is considered that the $Al_2O_3$ buffer layer could increase the carrier concentration of the GZO films by doping effect of diffused Al atoms through the rough interface.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.6
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• pp.338-342
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• 2011

Ga doped ZnO (GZO) thin films were deposited with RF magnetron sputtering on glass substrate and then the effect of post deposition annealing at nitrogen atmosphere on the structural, optical and electrical properties of the films was investigated. The post deposition annealing process was conducted for 30 minutes at different temperature of 150, 300 and $450^{\circ}C$, respectively. As increase annealing temperature, GZO films show the increment of the prefer orientation of ZnO (002) diffraction peak in the XRD pattern and the optical transmittance in a visible wave region was also increased, while the electrical sheet resistance was decreased. The figure of merit obtained in this study means that GZO films which vacuum annealed at $450^{\circ}C$ have the highest optoelectrical performance in this study.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.533-533
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• 2013

본 연구에서는 선형 대향 타겟 스퍼터 시스템을 이용하여 hetero sputtering방법으로 증착한Al-Ga-Zn-O (AGZO) 박막의 기판-타겟간 거리(Target-to-Substrate distance)에 따른 전기적, 광학적, 구조적 특성을 분석하였다. 타겟과 기판 사이의 거리 변화(30~120 mm)에 따른 AGZO 박막의 특성 변화를 관찰하기 위하여 일정한 DC 파워 250 W, 공정압력 0.3 mTorr, Ar 20 sccm에서 서로 다른 AZO 타겟과 GZO 타겟을 이용하여 hetero-sputtering 공정을 진행하였다. 최적의 타겟과 기판 사이의 거리를 결정하기 위해 AGZO 박막의 투과도(T)와 면저항($R_{sh}$)을 기반으로 figure of merit ($T^{10}/R_{sh}$)값을 계산하였다. 기판-타겟간 거리는 AGZO 박막의 밀도에 영향을 주는 핵심 인자로 30 mm에서 120 mm로 증가수록 밀도가 낮은 AGZO 박막이 형성되었다. 최적의 타겟과 기판 사이의 거리(30 mm)에서 AGZO 박막은 132 Ohm/sq의 낮은 면저항과 87.2%의 높은 투과도를 나타내었다. 그러나 기판-타겟간 거리가 증가할수록 같은 두께에서 면저항은 급격히 증가함을 발견할 수 있었으며 이러한 특성 변화는 스퍼터되어 기판에 도달하는 입자의 에너지 차이로 설명이 가능하다. 따라서 본 연구에서는 기판-타겟간 거리에 따른 AGZO 박막의 특성 변화를 설명할 수 있는 메커니즘을 다양한 분석을 통해 제시하였다. 또한 적화된 AGZO 투명 전극을 이용해 제작한 GaN-LED의 Damage free sputtering 기술에 대해서 소개한다.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.142-146
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• 2008

Trivalent ions(Ga, Al, In) doped ZnO films were deposited by DC magnetron sputtering on non-alkali glass substrate at substrate temperature of $300^{\circ}C$. We used the different three types of high density($95%{\sim}$) ceramic sintered disks(doped with $Ga_2O_3$; 6.65 wt%, $Al_2O_3$; 3.0 wt%, $In_2O_3$; 9.54 wt%). This study examined the effect of different dopants(Ga, Al, In) on the electrical, structural, and optical properties of the films. The lowest resistivity of $5.14{\times}10^{-4}{\Omega}cm$ and the highest optical band gap of 3.74 eV were obtained by Ga doped ZnO(GZO) film. All the films had a preferred orientation along the(002) direction, indicating that the growth orientation has a c-axis perpendicular to the substrate surface. The average transmittance of the films was more than 85% in the visible range.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.34-35
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• 2006

Transparent ZnO thin film transistor (TFT) is fabricated on the glass substrates. The device consists of a high mobility intrinsic ZnO as a semiconductor active channel, Ga doped ZnO (GZO) as an electrode, $HfO_2$ as a gate insulator. GZO and $HfO_2$ layers are prepared by using a pulsed laser deposition and intrinsic ZnO layers are fabricated by using an rf-magnetron sputtering, respectively. The transparent TFT is highly transparent (> 87 %) and exhibits n-channel, enhancement mode behavior with a field-effect mobility as large as $11.7\;cm^2/Vs$ and a drain current on-to-off ratio of about $10^5$.