• Journal of the Korean Society for Heat Treatment
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• v.28 no.3
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• pp.121-125
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• 2015

GZO single layer, Ni buffered GZO(GZO/Ni), Ni intermediated GZO (GZO/Ni/GZO) and Ni capped GZO (Ni/GZO) films were prepared on poly-carbonate (PC) substrates by RF and DC magnetron sputtering without intentional substrate heating and then the influence of the Ni (2 nm thick) thin film on the optical, electrical and structural properties of GZO films were investigated. As deposited GZO single layer films show the optical transmittance of 81.3% in the visible wavelength region and a resistivity of $1.0{\times}10^{-2}{\Omega}cm$, while GZO/Ni/GZO trilayer films show a lower resistivity of $6.4{\times}10^{-4}{\Omega}cm$ and an optical transmittance of 74.5% in this study. Based on the figure of merit, it can be concluded that the intermediated Ni thin film effectively enhances the opto-electrical performance of GZO films for use as transparent conducting oxides in flexible display applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.196-196
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• 2010

본 연구에서는 플렉시블 GZO 단일 박막과 GZO/Ag/GZO (GAG) 다층 박막을 연속 성막이 가능한 롤투롤 스퍼터링 시스템을 이용하여 상온 공정을 통해 성막하여 그 특성을 분석 하였다. 일반적으로 고품위의 GZO 박막을 제작하기 위해서는 고온 공정이 필수적인 것으로 알려져 있으나 본 실험에서는 플렉시블 PES 기판상에 상온 공정을 통해 후 열처리 없이 고품위의 GZO, GAG 박막을 얻을 수 있었다. 단일 GZO 박막은 공정 압력과 산소 유입량을 변화하여 제작하였고 GAG 다층 박막은 GZO-Ag-GZO로 이루어진 3개의 sputter gun을 이용하여 Ag 두께를 변수로 연속공정을 통해 제작하였다. 구조적, 표면석 특성 분석을 위해 XRD(X-ray diffraction), FE-SEM(Field emission scanning electron microscopy), HRTEM (High resolution electron microscopy)를 이용하였으며 광학적, 전기적 특성을 분석하기 위해 UV/Vis spectrometer, Hall effect measurement를 각각 이용하였다. 최적화된 GZO 단일 박막은 상온에서 열처리 없이 성막되었음에도 불구하고 38 ohm/sq의 낮은 저항과 86 %의 높은 투과도를 나타내었으며 GAG 다층 박막은 12 nm의 Ag 두께에서 6.4 ohm/sq의 낮은 저항과 88 %의 높은 투과율을 나타내었다. 특히 기계적 특성을 분석하기 위해 진행된 bending test에서 GAG 박막은 초기와 test 후에 저항과 표면에 변화가 없는 우수한 특성을 보였으며 이를 통해 플렉시블 태양전지와 디스플레이등 광학소자의 투명 전극으로서의 적용 가능성을 확인 할 수 있었다.

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.323-329
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• 2017

This reports the electrical behavior, bonding structure and Schottky contact of gallium-zinc-oxide (GZO) thin film annealed at $100{\sim}400^{\circ}C$. The mobility of GZO with high density of PL spectra and crystal structure was also increased because of the structural matching between GZO and Si substrate of a crystal structure. However, the GZO annealed at $200^{\circ}C$ with an amorphous structure had the highest mobility as a result of a band to band tunneling effect. The mobility of GZO treated at low annealing temperatures under $200^{\circ}C$ increased at the GZO with an amorphous structure, but that at high temperatures over $200^{\circ}C$ also increased when it was the GZO of a crystal structure. The mobility of GZO with a Schottky barrier (SB) was mostly increased because of the effect of surface currents as well as the additional internal potential difference.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.316-316
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• 2013

GZO/Ag/GZO 다층 투명 전도막은 투명 산화물 전극 사이에 빛이 투과할 수 있는 수준의 매우 얇은 금속을 삽입하여 낮은 면저항과 높은 투과율을 구현하는 기술로 금속의 유연성과 낮은 비저항, 산화물은 높은 투과도와 안정성을 동시에 이용할 수 있는 투명전도막이다. 본 연구에서는 RF 마그네트론 스퍼터와 전자빔 증착을 이용하여 GZO 박막 사이에 Ag 박막을 삽입한 GZO/Ag/GZO 구조의 박막을 제작하였다. Ag 박막의 두께와 공정 압력이 박막에 미치는 영향을 연구하였으며, 급속 열처리에 따른 GZO/Ag/GZO 박막의 특성을 분석하였다. Ag 삽입 박막 두께와 GZO/Ag/GZO 박막의 열처리 온도 최적화를 통하여 $2.2{\times}10-5{\Omega}{\cdot}cm$의 가장 낮은 비저항과 88.9%의 투과율을 나타내었다.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.140-144
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• 2012

Ga-doped ZnO (GZO) was a limit of application on the photovoltaic devices such as CIGS, CdTe and DSSC requiring high process temperature, because it's electrical resistivity is unstable above 300 ℃ at atmosphere. Therefore, ZTO (zinc tin oxide) was introduced in order to improve permeability and thermal stability of GZO film. The resistivity of GZO (300 nm) single layer increased remarkably from 1.8 × 10-3Ωcm to 5.5 × 10-1Ωcm, when GZO was post-annealed at 400 ℃ in air atmosphere. In the case of the ZTO (150 nm)/GZO (150 nm) double layer, resistivity showed relatively small change from 3.1 × 10-3Ωcm (RT) to 1.2 × 10-2Ωcm (400 ℃), which showed good agreement with change of carrier density. This result means that ZTO upper layer act as a barrier for oxygen at high temperature. Also ZTO (150 nm)/GZO (150 nm) double layer showed lower WVTR compared to GZO (300 nm) single layer. Because ZTO has lower WVTR compared to GZO, ZTO thin film acts as a barrier by preventing oxygen and water molecules to penetrate on top of GZO thin film.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.62.1-62.1
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• 2011

The structural, optical, and electrical properties of Ga-doped ZnO (GZO) thin films on glass substrates grown by radio-frequency(RF) magnetron sputtering were investigated. The flow ratio of Ar was varied as a deposition parameter for growing high-quality GZO thin films. The structural properties and surface morphologies of GZO were characterized by the X-ray diffraction. To analyze the optical properties of GZO, the optical absorbance was measured in the wavelength range of 300-1100 nm by using UV-VIS spectrophotometer. The optical transmittance, absorption coefficient, and optical bandgap energy of GZO thin films were calculated from the measured data. The crystallinity of GZO thin films is improved and the bandgap energy increases from 3.08 to 3.23eV with the increasing Ar flow ratio from 10 to 100 sccm. The average transmittance of the films is over 88% in the visible range. The lowest resistivity of the GZO is $6.215{\times}10^{-4}{\Omega}{\cdot}cm$ and the hall mobility increases with the increasing Ar flow ratio. We can optimize the characteristics of GZO as a transparent electrode for thin film solar cells by controlling Ar flow ratio during deposition process.

• Journal of the Korean institute of surface engineering
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• v.45 no.3
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• pp.117-122
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• 2012

ZTO/GZO double layered films were prepared on unheated non-alkali glass substrates. ZTO films were deposited by RF/DC hybrid magnetron co-sputtering using ZnO (RF) target and $SnO_2$ (DC) targets, and then GZO films were deposited by DC magnetron sputtering using an GZO ($Ga_2O_3$:5.57 wt%) target. These films were post-annealed at temperature of 200, $300^{\circ}C$ in air and vacuum ambient for 30 min. In the case of post-annealing in air, ZTO/GZO double layer showed relatively low resistivity change, compared to GZO single layer. Furthermore, ZTO/GZO double layer revealed low WVTR, compared to GZO single layer. Therefore, it can be confirmed that ZTO film doing a role with barrier for water or oxygen diffusion.

• Journal of the Semiconductor & Display Technology
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• v.15 no.1
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• pp.52-55
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• 2016

GZO film was prepared on p-type Si wafer and then annealed at various temperatures in an air conditions to research the bonding structures in accordance with the annealing processes. GZO film annealed in an atmosphere showed the various bonding structure depending on annealing temperatures and oxygen gas flow rate during the deposition. The difference of bonding structures of GZO films made by oxygen gas flows between 18 sccm and 22 sccm was so great. The bonding structures of GZO films made by oxygen gas flow of 18 sccm were showed the crystal structure, but that of 22 sccm were showed the amorphous structure in spite of after annealing processes. The bonding structure of GZO as oxide-semiconductor was observed the trend of becoming amorphous structures at the temperature of $200^{\circ}C$. Therefore, the characteristics of oxide semiconductor are needed to research the variation near the annealing at $200^{\circ}C$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1393-1398
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• 2015

In this study, the electrical and optical properties of GZO (Ga-doped ZnO) thin films prepared on PES substrates by RF magnetron sputtering method with various working pressures (5 to 20 mTorr) were investigated. All GZO thin films exhibited c-axis preferential growth regardless of working pressure, the GZO thin film deposited at 5 mTorr showed the most excellent crystallinity having 0.44˚ of FWHM. In AFM observations, surface roughness exhibited the lowest value of 0.20 nm in a thin film produced by the working pressure 5 mTorr. Figure of merits of GZO thin film deposited at 5 mTorr showed the highest value of 6652, in this case resistivity and average transmittance in the visible light region were 6.93×10^-4Ω-cm and 81.4%, respectively. We could observed the Burstein-Moss effect that carrier concentration decrease with the increase of working pressure and thus the energy band gap is narrowed.

• Journal of the Korean institute of surface engineering
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• v.43 no.3
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• pp.148-153
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• 2010

Transparent conducting films having a hybrid structure of GZO/Metal/GZO were prepared on glass substrates by sequential deposition using DC magnetron sputtering. Silver, copper, aluminum and zinc thin films were used as the intermediate metal layers in the hybrid structure. The electrical and optical properties of hybrid transparent conducting films were investigated with varying the thickness of metal layer or GZO layers. With increasing the metal thickness, hybrid films showed a noticeable improvement of the electrical conductivity, which is mainly dependent on the electrical property of the metal layer. GZO(40 nm)/Ag(10 nm)/GZO(40 nm) film exhibits a resistivity of $5.2{\times}10^{-5}{\Omega}{\cdot}cm$ with an optical transmittance of 82.8%. For the films with Zn interlayer, only marginal reduction in the resistivity was observed. Furthermore, unlike other metals, hybrid films with Zn interlayer showed a decrease in the resistivity with increasing the GZO thickness. The optimal thickness of GZO layer for anti-reflection effect at a given thickness of metal (10 nm) was found to be critically dependent on the refractive index of the metal. In addition, x-ray diffraction analysis showed that the insertion of Ag layer resulted in the improvement of crystallinity of GZO films, which is beneficial for the electrical and optical properties of hybrid-type transparent conducting films.