• Proceedings of the Korean Vacuum Society Conference
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• 2001.07a
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• pp.67-67
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• 2001

• ETRI Journal
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• v.31 no.6
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• pp.653-659
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• 2009

We have investigated the channel protection layer (PL) effect on the performance of an oxide thin film transistor (TFT) with a staggered top gate ZnO TFT and Al-doped zinc tin oxide (AZTO) TFT. Deposition of an ultra-thin PL on oxide semiconductor films enables TFTs to behave well by protecting the channel from a photo-resist (PR) stripper which removes the depleted surface of the active layer and increases the carrier amount in the channel. In addition, adopting a PL prevents channel contamination from the organic PR and results in high mobility and small subthreshold swings. The PL process plays a critical role in the performance of oxide TFTs. When a plasma process is introduced on the surface of an active layer during the PL process, and as the plasma power is increased, the TFT characteristics degrade, resulting in lower mobility and higher threshold voltage. Therefore, it is very important to form an interface using a minimized plasma process.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.98-98
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• 2011

수직으로 정렬된 1차원 나노구조는 입사되는 빛에 대하여 반사율을 줄일 수 있는 유효 굴절률 profile을 갖고 있어, 태양광소자 및 광전자소자의 성능을 향상시키기 위해 널리 응용되어 왔으며, 이러한 수직으로 정렬된 1차원 나노구조를 제작하는 연구가 매우 활발하게 이루어지고 있다. 그 중 화학적 방법으로 성장시킨 산화아연 나노로드(ZnO nanorod)는 비교적 간단하고 저렴한 제작공정을 통해서 높은 결정성을 갖는 수직형 1차원 나노구조체로 이용 할 수 있다. 한편, 효과적인 무반사(antireflection) 층을 제작하기 위해서는 표면에서 발생되는 Fresnel 반사율을 낮춰야 하는데, 이를 위해서 입사되는 매질에서 기판 사이의 유효 굴절률이 연속적이고, 점진적인 변화가 필요하다. 이에 본 연구에서는 무반사 특성향상을 위해서 실리콘 (Si) 기판위에 tapered 산화아연 나노로드를 화학적으로 성장시켜 반사율 특성을 분석하였다. 실험을 위해, 먼저 Si 기판에 AZO (Al doped ZnO) seed 층을 RF magnetron 스퍼터를 사용해 증착한 후, zinc nitrate $Zn(NO_3)_2{\cdot}6H_2O$과 hexamethylentetramines으로 혼합된 용액에 담가두어 산화아연 나노로드를 성장시켰다. Tapered 산화아연 나노로드를 형성하기 위해 용액의 온도를 서서히 낮춤으로 산화아연나노로드의 끝을 뾰족하게 제작할 수 있었다. 한편, 이론적으로 AZO seed 층의 두께에 대한 반사 스펙트럼을 rigorous coupled wave analysis (RCWA) 계산법을 통해서 시뮬레이션을 수행하였으며, 최적화된 AZO seed 층의 두께를 결정하여, 그 위에 tapered 산화아연 나노로드를 성장시켜 반사율을 측정하여 무반사 특성 향상을 확인 할 수 있었다. 또한, 태양광소자 응용을 위해, 표준 AM1.5G 태양광 스펙트럼을 고려한 solar weighted reflection을 계산하였다.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.66-69
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• 2017

Physically implanted surface islands of Nano Carbon Tube (NCT) and ${\alpha}-F_2O_3$ particles have been produced on Al-doped ZnO (AZO)/glass surfaces by simple and direct ND:YAG laser beam irradiation. Sheet resistance of the reconstructed surface increased by about 3.6% of over AZO. Minimal surface damage can be repaired by ND:YAG laser beam irradiation in conjunction with proper impurities. Implanted islands of NCT, which are considered to be a good conductive impurity, on AZO increased the sheet resistance by about 1.8%, while implanted islands of ${\alpha}-F_2O_3$, an insulating impurity, on AZO increased sheet resistance by about 129% compared with a laser beam treated AZO. This study provides insight regarding surface implantations of nanowires and micro-circuits, doping effects for semiconductors and optical devices, surface area and impurity effects for catalysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.321-322
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• 2009

Al doped ZnO films deposited on glass substrate using RF magnetron sputtering in Ar and $Ar+H_2$ gas ambient at $100^{\circ}C$. The films deposited in $Ar+H_2$ were hydrogen-annealed at the temperature of $150\sim300^{\circ}C$ for 1hr. The lowest resistivity of $4.25\times10^{-4}{\Omega}cm$ was obtained for the AZO film deposited in $Ar+H_2$ after hydrogen annealing at $300^{\circ}C$ for 1hr. The average transmittance is above 85% in the range of 400-1000 nm for all films. The absorption efficiency of solar cell was improved by using the optimized AZO films as a top electrode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1144-1148
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• 2006

We have investigated liquid crystal (LC) aligning capabilities and electro-optical (EO) characteristics of transparent electrodes as Al-doped ZnO (AZO) substituting indium tin oxide (ITO). The experiment results show that a uniform vertical LC alignment on AZO electrodes based on a rubbed polyimide (PI) surface were achieved. A high pretilt angle of about $88^{\circ}$ was obtained. EO performances of the VA cell on rubbed PI surfaces with AZO electrodes are almost the same as that of the VA cell with ITO electrodes. These results appeared that AZO electrodes as transparent electrodes of LCDs could substitute ITO electrodes.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.149-149
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• 2009

실제 산업에서 가장 많이 사용하고 있는 in-line type system에서 Al-doped ZnO (AZO) 막을 bipolar pulsed DC sputtering을 이용해 증착하였다. 약 30 nm/sec의 속도로 기판을 타겟 좌우로 swing 하면서 동적 증착 공정을 한 AZO 박막의 columnar structure가 정적 증착일 때와 다른 형태의 zigzag-type columnar structure가 형성되었다. 투명전도막의 가장 중요한 특성인 비저항과 투과도가 동적 증착 공정일 때의 박막과 정적 증착 공정일 때의 박막이 각각 $2.5{\times}10^{-3}{\Omega}{\cdot}cm$, 78.5%와 $1.65{\times}10^{-3}{\Omega}{\cdot}cm$, 83.9% 였다. 이렇게 성장하는 막의 구조 형태에 따라 달라지는 특성 변화는 양산하는 현장에서 매우 중요한 것이며, 동적 증착 공정에서의 박막 특성 개선에 정적 증착 공정과는 다른 방법의 연구가 필요할 것이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.594-594
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• 2012

Al doped ZnO (AZO) thin films were deposited on textured glass substrate by magnetron sputtering method. Also, AZO films on textured glass were etched by hydrochloric acid (HCl). Average thickness of etched AZO films are 90 nm. We observed morphology of AZO film by AFM with various etchant concentration and etching time. Etched AZO films have low resistivity and high haze. The surface RMS roughness of AZO film was increased from 53.8 nm to 84.5 nm. The haze ratio was also enhanced in above 700 nm of wavelength due to light trapping effect was increased by rough AZO surface. The etched AZO films on textured glass are applicable to fabricate solar cell.

• Journal of the Semiconductor & Display Technology
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• v.15 no.4
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• pp.36-40
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• 2016

The 2 wt.% Al-doped ZnO(AZO) thin films were fabricated on PET substrates with various RF power 20, 35, 50, 65, and 80W by using RF magnetron sputtering in order to investigate the structure, electrical and optical properties of AZO thin films in this study. The XRD measurements showed that AZO films exhibit c-axis orientation. At a RF power of 80W, the AZO films showed the highest (002) diffraction peak with a FWHM of 0.42. At a RF power of 65W, the lowest electrical resistivity was about $1.64{\times}[10]$ ^(-4) ${\Omega}-cm$ and the average transmittance of all films including substrates was over 80% in visible range. Good transparence and conducting properties were obtained due to RF power control. The obtained results indicate that it is acceptable for applications as transparent conductive electrodes.

• Journal of the Semiconductor & Display Technology
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• v.15 no.3
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• pp.30-34
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• 2016

We investigated magnetic field, discharged voltage, and as-deposited film uniformity at facing targets sputtering (FTS) system with magnetic field type: i) concentrated and ii) distributed magnetic field type. And Al doped ZnO (AZO) films were prepared at two magnetic field type such as concentrated magnetic field type and distributed magnetic field type, respectively. Discharge voltage at the distribution type is lower than concentration type due to low magnetic flux (middle magnetic flux: Concentration 1200 G and Distribution 600 G). The films deposited at the distributed magnetic field were more uniform than concentration type. All of prepared AZO films had a resistivity of under $10^{-4}[{\Omega}{\cdot}cm]$ and a transmittance of more than 85 % in the visible range.