• 한국전기전자재료학회논문지
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• 제26권1호
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• pp.56-63
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• 2013

IGZO thin films have been prepared by RF magnetron sputtering. The structural, electrical and optical properties of the IGZO thin films have been investigated as a function of deposition condition. XRD analysis of IGZO thin films showed a typical crystallographic orientation with c-axis perpendicular regardless of deposition conditions. The carrier mobility, carrier concentration and resistivity of the IGZO films sputtered at 200 W, 1mTorr and $300^{\circ}C$ were $28.5cm^2/V{\cdot}sec$, $2.6{\times}10^{20}cm^3$, $8.8{\times}10^{-4}{\Omega}{\cdot}cm$ respectively. The optical transmittance were higher than 80% at visible region regardless of the deposition conditions under the experiments above, and specifically higher than 90% at wave length over 500 nm. The absorption edge was shifted to shorter wavelength with increase of carrier concentration.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.497-497
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• 2013

Semiconducting amorphous InGaZnO (a-IGZO) has attracted significant research attention as improved deposition techniques have made it possible to make high-quality a-IGZO thin films. IGZO thin films have several advantages over thin film transistors (TFTs) based on other semiconducting channel layers.The electron mobility in IGZO devices is relatively high, exceeding amorphous Si (a-Si) by a factor of 10 and most organic devices by a factor of $10^2$. Moreover, in contrast to other amorphous semiconductors, highly conducting degenerate states can be obtained with IGZO through doping, yet such a state cannot be produced with a-Si. IGZO thin films are capable of mobilities greaterthan 10 $cm^2$/Vs (higher than a-Si:H), and are transparent at visible wavelengths. For oxide semiconductors, carrier concentrations can be controlled through oxygen vacancy concentration. Hence, adjusting the oxygen partial pressure during deposition and post-deposition processing provides an effective method of controlling oxygen concentration. In this study, we deposited IGZO thinfilms at optimized conditions and then analyzed the film's electrical properties, surface morphology, and crystal structure. Then, we explored how to generate IGZO thin films using DC magnetron sputtering. We also describe the construction and characteristics of a bottom-gate-type TFT, including the output and transfer curves and bias stress instability mechanism.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.297-297
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• 2010

Transparent conductive Oxide (TCO) is an essential material in the various optoelectronic applications as a transparent electrode, such as solar cells, flat panel displays and organic light emitting diodes. Currently, Indium tin oxide (ITO) is commonly used in industry due to its low electrical resistivity, high transmittance and high adhesion to substrate. However, ITO is expensive and should be prepared at high temperature, which makes it hard to use ITO in flexible devices. In this regard, Ga-doped ZnO is expected as an ideal candidate for replacing ITO.

• 한국전기전자재료학회논문지
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• 제23권5호
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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 $1.90{\times}10^{-3}{\Omega}-cm$.

• 한국재료학회지
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• 제27권2호
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• pp.69-75
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• 2017

To establish low-temperature process conditions, process-property correlation has been investigated for Ga-doped ZnO (GZO) thin films deposited by pulsed DC magnetron sputtering. Thickness of GZO films and deposition temperature were varied from 50 to 500 nm and from room temperature to $250^{\circ}C$, respectively. Electrical properties of the GZO films initially improved with increase of temperature to $150^{\circ}C$, but deteriorated subsequently with further increase of the temperature. At lower temperatures, the electrical properties improved with increasing thickness; however, at higher temperatures, increasing thickness resulted in deteriorated electrical properties. Such changes in electrical properties were correlated to the microstructural evolution, which is dependent on the deposition temperature and the film thickness. While the GZO films had c-axis preferred orientation due to preferred nucleation, structural disordering with increasing deposition temperature and film thickness promoted grain growth with a-axis orientation. Consequently, it was possible to obtain a good electrical property at relatively low deposition temperature with small thickness.

• 한국표면공학회지
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• 제48권6호
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• pp.322-328
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• 2015

We investigated the diffusion behaviors, electrical properties, microstructures, and composition of In-Ga-Zn-O (IGZO) oxide thin films deposited by radio frequency reactive magnetron sputtering with increasing annealing temperatures. The samples were deposited at room temperature and then annealed at 300, 400, 500, 600 and $700^{\circ}C$ in air ambient for 2 h. According to the results of time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy, no diffusion of In, Ga, and Zn components were observed at 300, 400, 500, $600^{\circ}C$, but there was a diffusion at $700^{\circ}C$. However, for the sample annealed at $700^{\circ}C$, considerable diffusion occurred. Especially, the concentration of In and Ga components were similar at the IGZO thin film but were decreased near the interface between the IGZO and glass substrate, while the concentration of Zn was decreased at the IGZO thin film and some Zn were partially diffused into the glass substrate. The high-resolution transmission electron microscopy results showed that a phase change at the interface between IGZO film and glass substrate began to occur at $500^{\circ}C$ and an unidentified crystalline phase was observed at the interface between IGZO film and glass substrate due to a rapid change in composition of In, Ga and Zn at $700^{\circ}C$. The best values of electron mobility of $15.5cm^2/V{\cdot}s$ and resistivity of $0.21{\Omega}cm$ were obtained from the sample annealed at $600^{\circ}C$.

• 한국표면공학회지
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• 제44권6호
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• pp.250-254
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• 2011

NiO-AZO films were deposited on glass substrate by DC and RF magnetron co-sputtering system in pure $O_2$ gas without substrate heating during deposition. In order to control the chemical composition of the film, NiO target was supplied with constant RF power of 150 W and AZO target (doped with 2.98 at% aluminum) with DC power varied between 40 W to 80 W. Deposited NiO-AZO films were evaluated by structural and chemical analysis. With introducing AZO, XRD and XPS data reveal that NiO were supplied with more oxygen. these results could be strongly affected by the higher bond enthalpy of NiO compared to ZnO, which makes it possible for NiO to obtain excessive oxygen from ZnO.

• 열처리공학회지
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• 제24권6호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.153-153
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• 2006

ZnO 박막은 II-VI족 화합물 반도체로서 상온에서 3.37eV 의 넓은 밴드갭을 가지고 있을 뿐만 아니라 GaN(28meV) 보다 상온에서 큰 엑시톤 결합 에너지(60meV)와 열 안정성을 가지고 있다. 특히 ZnO를 base로 한 2차원의 화합물 (MgZnO, CdZnO 그리고 MgO) 반도체 물질은 UV LED, 생 화학 센서와 투명전극 등으로 응용이 가능하다. ZnO/MgZnO 양자우울 구조의 양자제한 효과로 인한 엑시톤 결합에너지와 전기적 광학적 특성 향상으로 광전자 소 자 제작이 가능하다. 그렇지만, Zn-Mg 상평형도에서 ZnO 내에 Mg 고용도가 상온에서 열역학적으로 4at% 이하 이고, 또한 ZnO와 MgO는 각각 우르짜이트 구조와 면심입방 구조를 가지기 때문에 Mg 함량용 높이는데 어려움이 있다. 이러한 문제점을 해결하기 위해 열처리를 함으로써 MgZnO 박막 내에 Mg 함량의 증가와 결정성 향상으로 고품질의 광전자 소자 제작을 가능하게 했다. 본 실험에서는 RF 마그네트론 스퍼터링 장비로 MgZnO 박막 성장 후 Si 기판위에 성장된 박막의 결정성 향상과 MgZnO 내의 Mg 함량 변화를 관찰하기 위해 성장된 박막에 대한 열처리 효과를 연구 하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.65-65
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• 2006

ZnO 박막은 II-VI족 화합물 반도체로서 상온에서 3.37eV의 넓은 밴드갭을 가지고 있을 뿐만 아니라 GaN(28meV) 보다 상온에서 큰 엑시톤 결합 에너지(60meV)와 열 안정성을 가지고 있다. 특히 ZnO를 base로 한 2차원의 화합물 (MgZnO, CdZnO 그리고 MgO) 반도체 물질은 UV LED, 생 화학 센서와 투명전극 등으로 응용이 가능하다. ZnO/MgZnO 양자우물 구조의 양자제한 효과로 인한 엑시톤 결합에너지와 전기적 광학적 특성 향상으로 광전자 소 자 제작이 가능하다. 그렇지만, Zn-Mg 상평형도에서 ZnO 내에 Mg 고용도가 상온에서 열역학적으로 4at% 이하 이고, 또한 ZnO와 MgO는 각각 우르짜이트 구조와 면심입방 구조를 가지기 때문에 Mg 함량을 높이는데 어려움이 있다. 이러한 문제점을 해결하기 위해 열처리를 함으로써 MgZnO 박막 내에 Mg 함량의 증가와 결정성 향상으로 고품질의 광전자 소자 제작을 가능하게 했다. 본 실험에서는 RF 마그네트론 스퍼터링 장비로 MgZnO 박막 성장 후 Si 기판위에 성장된 박막의 결정성 향상과 MgZnO 내의 Mg 함량 변화를 관찰하기 위해 성장된 박막에 대한 열처리 효과를 연구 하였다.