• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.345.2-345.2
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• 2016

Alumina (Al2O3) doped zinc oxide (ZnO) films (AZO) have been prepared from 2 wt.% Al2O3 doped ZnO target by DC magnetron sputtering at a 2 mTorr (0.27 Pa) chamber pressure in (15 sccm) argon ambient. We obtained films of various opto-electronic properties by variation of target angle from 32.5o to 72.5o. At lower target angle deposited films show higher values in optical gap, mobility of charge carrier, carrier concentration, crystallite grain size, transmission range of wavelength, which are favorable characteristics of AZO as a transparent conducting oxide (TCO). At higher target angle the sheet resistance, work function, surface roughness for the AZO films increases. Measured haze ratio of the films changed lower to higher and size of characteristic surface structure of as deposited film ranges from ~40 nm to ~300 nm. By a combination of low and high target angle we obtained a textured TCO film with high conductivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.857-860
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• 2003

Tin doped indium oxide(ITO) and Al doped zinc oxide(ZnO:Al) films, which are widely used as a transparent conductor in optoelectronic devices such as solar cell, liquid crystal display, plasma display panel, thermal heater, and other sensors, were prepared by using the capacitively coupled DC magnetron sputtering method. The electrical and optical properties of both the ITO and ZnO:Al thin films were investigated as functions of substrate temperature, working gas pressure and deposition time. ITO and ZnO:Al films with the the present experimental conditions of temperature and pressure showed resistivity of $2.36{\times}10^{-4}{\Omega}-cm,\;9.42{\times}10^{-4}{\Omega}-cm$ and transmittance of 86.28%, 90.88% in the wavelength range of the visible spectrum, respectively.

• 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 Korean Vacuum Society Conference
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• 2012.08a
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• pp.422-422
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• 2012

투명전극 산화막은 태양전지, 평판 디스플레이 등의 투명전극과 같은 광전자 소자에 사용되고 있다. 투명 전도성 산화막으로서 ITO (Indium tin oxide)는 높은 투과도, 낮은 비저항, 높은 일함수 등의 장점을 가지고 있어서 그동안 널리 사용되어 왔다. 그러나 In의 희소성으로 인한 고가격 문제 때문에 이를 대체하기 위해 불순물을 도핑한 ZnO (Zinc oxide)에 관한 연구가 활발히 진행되어 왔다. ZnO의 전기전도도를 높이기 위해 일반적으로 Al, Ga, B와 같은 3족 원소가 ZnO의 n형 도펀트로 널리 사용된다. 그 중에서 Al은 반응성이 커서 박막 증착 중에 산화되기 쉬운 반면 낮은 생산단가, 우수한 전기적 및 광학적 특성을 보이기 때문에 투명 전극으로서 Al-doped ZnO (AZO)가 많이 이용되고 있다. 본 연구에서는 rf 마그네트론 스퍼터링 공정을 이용하여 glass 기판 위에 Al-doped ZnO (AZO) 투명 전도막을 증착하였고, 수명 및 신뢰성에 영향에 미치는 주요 인자로서 온도, 온도 사이클 및 습도에 따른 AZO 박막의 열화 특성에 대한 연구를 진행하였다. 또한, 온도 사이클, 고온 및 고온고습 환경에 장시간 노출된 AZO 박막들의 성능 저하 원인들을 미세구조 관찰, 전기적 및 광학적 특성 변화들을 연계하여 규명하고자 하였다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.378-382
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• 2003

Transparent conductive oxides (TCO) are necessary as front electrode for most thin film solar cell. In our paper, transparent conducting aluminum-doped Zinc oxide films (ZnO:Al) were prepared by rf magnetron sputtering on glass (Corning 1737) substrate as a variation of the deposition condition. After deposition, the smooth ZnO:Al films were etched in diluted HCI (0.5%) to examine the electrical and surface morphology properties as a variation of the time. The most important deposition condition of surface-textured ZnO films by chemical etching is the processing pressure md the substrate temperature. In low pressures (0.9mTorr) and high substrate temperatures ($\leq$$300^{\circ}C$), the surface morphology of films exhibits a more dense and compact film structure with effective light-trapping to apply the silicon thin film solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.391-394
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• 2002

Transparent conductive oxides (TCO) are necessary as front electrode for most thin film solar cell. In our paper, transparent conducting aluminum-doped Zinc oxide films (ZnO:Al) were prepared by rf magnetron sputtering on glass (Corning 1737) substrate as a variation of the deposition condition. After deposition, the smooth ZnO:Al films were etched in diluted HCl (0.5%) to examine the electrical and surface morphology Properties as a variation of the time. The most important deposition condition of surface-textured ZnO films by chemical etching is the processing pressure and the substrate temperature. In low pressures (0.9 mTorr) and high substrate temperatures ($\leq$30$0^{\circ}C$), the surface morphology of films exhibits a more dense and compact film structure with effective light-trapping to apply the silicon thin film solar cells.

• Journal of information and communication convergence engineering
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• v.5 no.3
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• pp.219-222
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• 2007

Highly conductive and transparent aluminum doped ZnO thin films (AZO) films have been prepared by r.f. magnetron sputtering processes on poly carbonate (PC) and onto glass as reference. In addition, the electrical, optical properties of the films prepared at various sputtering powers were investigated. The XRD measurements revealed that all of the obtained films were polycrystalline with the hexagonal structure and had a preferred orientation with the c-axis perpendicular to the substrate. The ZnO:Al films were increasingly dark gray colored as the sputter power increased, resulting in the loss of transmittance. High quality films with the resistivity as low as $9.7{\times}10^{-4}\;{\Omega}-cm$ and transmittance over 90% have been obtained by suitably controlling the r.f. power.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.500-501
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• 2005

Aluminum doped zinc oxide films (ZnO:Al) were deposited on glass substrate by DC magnetron sputtering from a ZnO target mixed with 2 wt% $Al_2O_3$. The effects of substrate bias on the electrical properties and film structure were studied. Films deposited with positive bias have been annealed at $600^{\circ}C$ using rapid thermal anneal (RTA) process. The effects of RTA on the evolution of film microstructure are to be also studied using X-ray diffraction, transmission electron microscopy, and atomic force microscopy. Positive bias sputtering may induce lattice defects caused by electron bombardments during deposition. The as-deposited film microstructure evolves from the film with high defect density to more stable film condition. The electrical properties of the films after RTA process were also studied and the results were correlated with the evolution of film microstructures.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.175-175
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• 2010

Transparent conducting oxide (TCO) films are widely used as transparent conducting thin film material for application in various fields such as solar cells, optoelectronic devices, heat mirrors and gas sensors, etc. Recently the increased utilization of many transparent electrodes has accelerated the development of inexpensive TCO materials. Indium tin oxide (ITO) film is well-known for TCO materials because of its low resistivity, but there is disadvantage that it is too expensive. ZnO film is cheaper than ITO but it shows thermally poor stability. On the contrary, antimony-doped tin oxide films (ATO) are more stable than TCO films such as Al-doped zinc oxide (AZO) and ITO. Moreover, SnO2 film shows the best thermal and chemical stability, low cost and mechanical durability except the poor conductivity. However, annealing is proved to improve the conductivity of ATO film. Therefore, in this work, antimony (6 wt%) doped tin oxide films to improve the conductivity were deposited on 7059 corning glass by RF magnetron sputtering method for the application to transparent electrodes. In general, of all TCO films, glass is the most commonly selected substrate. However, for future development in flexible devices, glass is limited by its intrinsic inflexibility. In this study, we report the growth and properties of antimony doped tin oxide (ATO) films deposited on PES flexible substrate by using RF magnetron sputtering. The optimization process was performed varying the sputtering parameters, such as RF power and working pressure, and parameter effect on the structural, electrical and optical properties of the ATO films were investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.95-95
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• 2011

비정질 산화물 반도체(Amorphous oxide semiconductors: AOSs)는 대면적화에도 불구하고 높은 이동도를 가지고, 상온에서도 제작할 수 있고, 투명 플렉시블 디스플레이 소자에 사용할 수 있기 때문에 최근 들어 각광받고 있는 연구 분야이다. 본 연구에서는 스퍼터링을 이용하여 활성층을 Amorphous indium gallium zinc oxide(a-IGZO)로 증착할 시에 스퍼터의 파워와 챔버내의 Ar/O2 비율을 다르게 했을 때 소자에 미치는 영향을 MIS구조를 이용하여 분석했다. 또한 같은 조건의 a-IGZO 활성층을 사용한 박막트랜지스터(TFT) 소자의 절연막의 종류를 바꿔가며 제작했을때의 소자의 특성 변화에 대해서도 분석하였다. 먼저 60 nm 두께의 a-IGZO층을 Heavily doped된 N형 실리콘 기판위에 스퍼터링 파워와 가스 분압비를 달리하여 증착하였다. 그 후 30 nm두께의 SiO2, Al2O3, SiNx 절연막을 증착하고, 마지막으로 열 증발 증착장비(Thermal Evaporator)를 이용하여 Al 전극을 150nm 증착하였다. 소자의 전기적 특성 분석은 HP4145와 Boonton 720을 사용하여 I-V와 C-V를 측정하였다. 위의 실험으로부터 스퍼터에서의 증착 rf파워가 증가할수록 a-IGZO 박막 트랜지스터에서의 캐리어 이동도가 감소하는 것을 볼 수 있었고, 챔버내의 가스분압비와 소자의 절연막의 종류가 변하면 a-IGZO 박막 트랜지스터의 전기적 특성이 변하는 것을 볼 수 있었다. 이러한 캐리어 이동도의 감소와 전기적 특성의 변화의 이유는 a-IGZO 활성층의 bulk trap과 절연막, 활성층 사이의 interface trap에 의한 것으로 보여진다.