• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.6-6
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• 2010

Indium Tin Oxide (ITO)를 포함한 Transparent Conduction Oxide (TCO)는 LCD, OLED와 같은 Display, 그리고 Solar Cell 등 광신호와 전기신호간 변환이 필요한 모든 Device에 반드시 필요한 핵심 물질로, 특히 고특성 Display의 투명전극에서 요청되는 95% 이상의 투과도와 $15\;{\Omega}/{\square}$ 이하의 면저항 특성을 동시에 만족할 수 있는 기술은 현재까지 Plasma Sputtering 공정으로 $160^{\circ}C$ 이상에서 증착된 ITO 박막이 유일하다. 그러나, 최근 차세대 기술로서 Plastic Film을 기반으로 하는 Flexible Display 및 Flexible Solar Cell 구현에 대한 요구가 급증하면서, Plastic Film 기판위에 Plasma Damage이 없이 상온에 가까운 저온 ($100^{\circ}C$ 이하)에서 특성이 우수한 ITO 투명전극을 형성 할 수 있는 기술의 확보가 중요한 현안이 되고 있다. 지난 10년 동안 $100^{\circ}C$이하 저온에서 고특성의 ITO 또는 TCO 박막을 얻기위한 다양한 연구와 구체적인 공정이 활발히 연구되어 왔으나, ITO의 결정화 온도 (통상 $150{\sim}180^{\circ}C$)이하에서 증착된 ITO박막은 비정질 상태의 물성적 특성을 보여 원하는 전기적, 광학적 특성확보가 어려웠다. 본 논문에선 기본적으로 절연체 특성을 가져야 하는 산화물인 TCO가 반도체 또는 도체의 물리적 특성을 보여주는 기본원리의 고찰을 토대로, 재료학적 특성상 Crystalline 구조를 보여야 하는 ITO (Complex Cubic Bixbyte Structure)가 Plasma Sputtering 공정으로 저온에서 증착될 때 비정질 구조를 갖게 되는 원인을 규명하고, 이를 바탕으로 저온에서 증착된 ITO가 Crystalline 구조를 유지 할 수 있게 하고, Stress Control에 유리한 Nano-Crystalline 박막을 형성하면서 Crystallinity를 임의로 조절 할 수 있는 새로운 기술인 Magnetic Field Shielding Sputtering (MFSS) 공정과 최근 성과를 소개한다. 한편, 또 다른 새로운 저온 TCO 박막형성 기술로서, 유기반도체와 같은 Process Damage에 매우 취약한 유기물 위에 Plasma Damage 없이 TCO 박막을 직접 형성할 수 있는 Neutral Beam Assisted Sputtering (NBAS) 기술의 원리를 설명하고, 본 공정을 적용한 Top Emission OLED 소자의 결과를 소개한다. 또한, 고온공정이 수반되는 Solar Cell용 투명전극의 경우, 통상의 TCO박막이 고온공정을 거치면서 전기적 특성이 열화되는 원인을 규명하고, 이에 대한 근본적 해결 방법으로 ITO 박막의 Dopant인 Tin (Sn) 원자의 활성화를 증가시킨 Inductively Coupled Plasma Assisted DC Magnetron Sputtering (ICPDMS)의 원리와 박막의 물성적 특성과 내열 특성을 소개한다.

• Journal of the Korean Ceramic Society
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• v.43 no.9 s.292
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• pp.532-536
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• 2006

The annealing temperature effect of transparent conducting oxide film grown on glass substrate for solar cell application was studied in this paper. Using pulsed DC magnetron sputtering with 1 at% Al-doped ZnO target, TCO films were deposited on coming 7059 glass at room temperature. Al:ZnO thin films were annealed at 200, 400, Al $600^{\circ}C$ for 10 min and annealing resulted in lower biaxial compressive stress of about 1GPa and increased average crystallite size in all films. The as-grown film shows the resistivity of $1{\times}10^{-2}{\Omega}{\cdot}cm$ and transmittance under 80%, whereas the electrical and optical properties of film annealed at $400^{\circ}C$ are enhanced up to $5{\times}10^{-4}{\Omega}{\cdot}cm$ and 85%, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.165-168
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• 2004

In this study, AZO(ZnO:Al) thin film were prepared by FTS(Facing Target Sputtering) system. The electrical, optical and crystallographic properties of AZO thin film with $O_2$ gas flow ratio have been investigated. The thickness, transmittance, crystal structure and resistivity of AZO thin film were measured by a-step, UV-VIS spectrometer, XRD and four-point probe, respectively. As a result AZO thin film deposited with the transmittance over 80% and the resistivity about $10^{-1}\Omega-cm$.

• 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.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.10
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• pp.923-929
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• 2008

On the piezoelectric polymer, PVDF (poly vinylidene fluoride), the transparent conducting oxide (TCO) electrode material thin film was deposited by roll to roll sputtering process mentioned as a mass product-friendly process for display application. The deposition method for ITO Indium Tin Oxides) as our TCO was DC magnetron sputtering optimized for polymer substrate with the low process temperature. As a result, a high transparent and good conductive ITO/PVDF film was prepared. During the process, especially, the gas mixture ratio of Ar and Oxygen was concluded as an important factor for determining the film's physical properties. There were the optimum ranges for process conditions of mixture gas ratio for ITO/PVDF From these results, the doping mechanism between the oxygen atom and the metal element, Indium or Tin was highly influenced by oxygen partial pressure condition during the deposition process at ambient temperature, which gives the conductivity to oxide electrode, as generally accepted. With our studies, the process windows of TCO for display and other application can be expected.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.369-369
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• 2007

ZnO film has been investigated during several decades because it has excellent optical property like a transmittance among the range of visible light for using transparent conducting oxide (TCO) films. But ZnO film has not enough conductivity for applying to TCO devices. Therefore we synthesized platinum nanoparticles and they incorporated into ZnO due to improve the electrical property of ZnO film by sol-gel synthesis method. Also, we fabricated photosensitive ZnO thin film containing Pt nanoparticles by sol-gel process and spin-coating for using photochemical solution deposition. Photosensitive ZnO film could carry out the direct-pattern which allow the etching process to be convenient. The optical and electrical properties of ZnO film with or without various atomic percent of Pt nanoparticles annealed at various temperatures were investigated by using UV-Vis spectroscopy and 4-point probe method, respectively. We characterized the ZnO thin film containing Pt nanoparticles using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.725-729
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• 2014

In this study, a transparent conductive oxide (TCO)-less dye-sensitized solar cells (DSSCs) was fabricated by using titanium (Ti) electrode to replace the Fluorine-doped tin oxide (FTO) for the reduction of manufacturing cost. Ti film was formed by electron beam evaporation method and the results showed the sheet resistance of Ti electrodes with a thikness of 500 nm similar to FTO. In case of power conversion efficiency (PCE), a DSSC with Ti electrodes showed a lower value than that with FTO by 0.38%. For the investigation of the difference, the DSSCs were measured and analyzed by using electrochemical impedance analyzer (EIS).

• Current Photovoltaic Research
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• v.5 no.1
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• pp.28-32
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• 2017

In this paper, (Ga,Al):ZnO layers were deposited by sputtering to evaluate the device performance according to the thickness of the layer. As the thickness increased, low transmittance was observed, but the electrical resistance was improved. On the other hand, the highest efficiency was recorded at 400 nm device than a 500 nm of it. Therefore, since the critical thickness exists, it is necessary to set an adequate TCO layer thickness in consideration of the characteristics of the underlying film and the device.