• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.385-386
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• 2007

We prepared the Al doped ZnO coating Ag multilayer thin films on glass without substrate heating using FTS system. The structure of multilayer thin films has Al doped ZnO/Ag/Al doped ZnO(AZO/Ag/AZO). The thickness of top and bottom AZO thin films were fixed to 50 nm, respectively and controlled the thickness of Ag thin films with deposition time. As-doped multilayer thin films were prepared at 1mTorr and input power (DC) of 100W at room temperature. To investigate the film properties, we employed four-point probe, UVNIS spectrometer, X-ray diffractometer (XRD), scanning electron microscopy (SEM), Hall Effect measurement system and Atomic Force Microscope (AFM).

• 한국재료학회지
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• 제23권8호
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• pp.469-475
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• 2013

Al-doped ZnO(AZO) thin films were synthesized using atomid layer deposition(ALD), which acurately controlled the uniform film thickness of the AZO thin films. To investigate the electrical and optical properites of the AZO thin films, AZO films using ALD was controlled to be three different thicknesses (50 nm, 100 nm, and 150 nm). The structural, chemical, electrical, and optical properties of the AZO thin films were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, field-emssion scanning electron microscopy, atomic force microscopy, Hall measurement system, and UV-Vis spectrophotometry. As the thickness of the AZO thin films increased, the crystallinity of the AZO thin films gradually increased, and the surface morphology of the AZO thin films were transformed from a porous structure to a dense structure. The average surface roughnesses of the samples using atomic force microscopy were ~3.01 nm, ~2.89 nm, and ~2.44 nm, respectively. As the thickness of the AZO filmsincreased, the surface roughness decreased gradually. These results affect the electrical and optical properties of AZO thin films. Therefore, the thickest AZO thin films with 150 nm exhibited excellent resistivity (${\sim}7.00{\times}10^{-4}{\Omega}{\cdot}cm$), high transmittance (~83.2 %), and the best FOM ($5.71{\times}10^{-3}{\Omega}^{-1}$). AZO thin films fabricated using ALD may be used as a promising cadidate of TCO materials for optoelectronic applications.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.163-167
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• 2013

Aluminum doped zinc oxide (AZO) thin films have been prepared on the glass substrates (Corning 1737) by sol-gel dip-coating method employing zinc acetate and aluminum chloride hexahydrate for the transparent conducting oxide (TCO) applications. 1 at% Al was doped to the ZnO thin films. The effects of post-heating temperature on the crystallization, optical and electrical properties of the AZO films have been investigated. Experimental results showed that post-heating temperature affected the microstructure, electrical resistance, and optical transmittance of the AZO films. From the X-ray diffraction analysis, all films have hexagonal wurtzite crystal structure. Optical transmittance spectra of the AZO films exhibited transmittance higher than about 80% within the visible wavelength region and the optical direct band gap ($E_g$) of these films was increased with increasing post-heating temperature. A minimum resistivity of $2.5{\times}10^{-3}{\Omega}cm$ was observed at $650^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제24권3호
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• pp.177-181
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• 2011

We have studied structural, optical, and electrical properties of the Al-doped ZnO (AZO) thin films being usable in transparent conducting oxides. The AZO thin films were deposited on the corning 1737 glass plate by the RF magnetron sputtering system. To find optimal properties of AZO for transparent conducting oxides, the RF power in sputtering process was varied as 40 W, 60 W, and 80 W, respectively. As RF power increased, the crystallinity of AZO thin film was decreased, the optical bandgap of AZO thin film increased. The transmittance of the film was over 80% in the visible light range regardless of the changes in RF power. The measurement of Hall effect characterizes the whole thin film as n-type, and the electrical property was improved with increasing RF power. The structural, optical, and electrical properties of the AZO thin films were affected by Al dopant content in AZO thin film.

• 한국결정성장학회지
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• 제18권1호
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• pp.50-55
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• 2008

졸-겔 공정을 이용하여 유리기판 위에 Al-doped ZnO(AZO) 박막을 제조하였고, AZO 박막의 특성에 대하여 Al 전구체 종류 및 post-annealing 온도가 미치는 영향에 대하여 고찰하였다. AZO 박막 제조용 졸은 zinc acetate, EtOH, MEA 등을 사용하여 제조하였고, Al doping 을 위한 전구체로는 aluminum nitrate 와 aluminum chloride 를 사용하였다. Sol 내의 Zn 농도는 0.5 mol/l 로 하였고, Al doping 양은 Zn 대비 1 at%로 고정하였다. 유리기판 위에 졸을 spin-coating 한 후 $550^{\circ}C$에서 2 시간 동안 열처리한 후, $N_2$와 $H_2$의 비가 9 : 1인 환원 분위기 내에서 $300^{\circ}C,\;400^{\circ}C,\;500^{\circ}C$인 온도에서 2시간 동안 post-annealing을 진행하였다. 제조된 AZO 박막의 구조적, 전기적, 광학적 특성은 XRD, FE-SEM, AFM, Hall effect measurement system 및 UV-Visible spectroscopy를 이용하여 분석하였다. Al 전구체로서 aluminum nitrate 를 사용한 경우가 aluminum chloride 를 사용하여 제조한 AZO 박막보다 우수한 광학적, 전기적 특성을 나타내었으며, post-annealing 온도가 증가함에 따라 비저항과 투과율은 감소하였다. $500^{\circ}C$에서 post-annealing한 AZO 박막의 전기비저항 값은 $2{\times}10^{-3}{\Omega}{\cdot}cm$이었고, 투과율은 $300^{\circ}C$에서 91%로 가장 높게 나타났다.

• 반도체디스플레이기술학회지
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• 제6권3호
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• pp.35-39
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• 2007

ITO(Indium Tin Oxide) is the most attractive TCO(Transparent Conducting Oxide) materials for LCD, PDP, OLEDs and solar cell, because of their high optical transparency and electrical conductivity. However due to the shortage of indium resource, hard processing at low temperature, and decrease of optical property during hydrogen plasma treatment, their applications to the display industries are limited. Thus, recently the Al-doped ZnO(AZO) has been studied to substitute ITO. In this study, we have investigated the effect of different substrate temperature(RT, $150^{\circ}C$, $225^{\circ}C$, $300^{\circ}C$) and working pressure(10 mTorr, 20 mTorr, 30 mTorr, 80 mTorr) on the characteristics of AZO(2 wt.% Al, 98 wt.% ZnO) films deposited by RF-magnetron sputtering. We have obtained AZO thin films deposited at low temperature and all the deposited AZO thin films are grown as colunmar. The average transmittance in the visible wavelength region is over 80% for all the films and transmittance improved with increasing substrate temperature. Electrical properties of the AZO films improved with increasing substrate temperature.

• Current Photovoltaic Research
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• 제1권2호
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• pp.97-102
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• 2013

Aluminum-doped zinc oxide (AZO) thin films were prepared by dc magnetron sputtering at room temperature and the effect of heat treatment on the structural, electrical and optical properties of the films were examined. As the annealing temperature and time increased, the resistivity decreased and the transmittance improved. All AZO films had c-axis oriented (002) plane of ZnO, regardless of the annealing process employed. As the annealing temperature and time increased, the crystallinity of AZO thin films increased due to the formation of a new ZnO phase in which Al was substituted for Zn. However, at the high annealing temperature of $400^{\circ}C$, the resistivity of the films increased via separation of Zn and Al from ZnO phase due to their low melting points. X-ray diffraction, field emission scanning electron micrograph and Hall effect measurement confirmed the formation of uniformly distributed new grains of ZnO substituted with Al. The variation of Al contents in AZO films was shown to be the primary factor for the changes in resistivity and carrier concentration of the films.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.688-688
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• 2013

Al-doped ZnO (AZO) thin films have attracted a lot of attention as a cheap transparent conducting oxide (TCO) material that can replace the expensive Sn-doped In2O3. In particular, AZO thin films are widely used as a window layer of chalcogenide-based thin film solar cells such as Cu(In,Ga)Se2 and Cu2ZnSnS4 (CZTS). Mostly important requirements for the window layer material of the thin film solar cells are the high transparency and the low sheet resistance, because they influence the light absorption by the activelayer and the electron collection from the active layer, respectively. In this study, we prepared the AZO thin films by RF magnetron sputtering using a ZnO/Al2O3 (98：2wt%) ceramic target, and the effect of the sputtering condition such as the working pressure, RF power, and the working distance on the optical, electrical, and crystallographic properties of the AZO thin films was investigated. The AZO thin films with optimized properties were used as a window layer of CZTS thin film solar cells. The CZTS active layers were prepared by the electrochemical deposition and the subsequent sulfurization process, which is also one of the cost-effective synthetic approaches. In addition, the solar cell properties of the CZTS thin film solar cells, such as the photocurrent density-voltage (J-V) characteristics and the external quantum efficiency (EQE) were investigated.

• 한국전기전자재료학회논문지
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• 제29권5호
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• pp.279-283
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• 2016

In this study, we intended to achieve both antibacterial properties and electromagnetic shielding using the Al-doped ZnO (AZO) films. FTS (Facial Target Sputtering) magnetron sputtering was used for the AZO thin films instead of the conventional RF sputtering because the FTS sputtering could avoid the damage for the plasma as well as fabrication of thin films with a high quality. The 300-nm thick AZO thin films grown on glass substrate showed a resistivity of about $7{\times}10^{-4}{\Omega}-cm$ and a transmittance of about 90% at a wavelength of 550 nm. AZO thin films were investigated for the electromagnetic shielding effectiveness measured by 2-port network method at 1.5 ~ 3 GHz. The AZO (300 nm)/glass films showed an EMI shielding effectiveness of approximately 27 dB. An antibacterial effect was measured by the film attachment method (JIS Z 2801). The percent reductions of bacteria by AZO films were 99.99668% and 99.99999% against Staphylococcus aureus and Escherichia coli, respectively.

• 센서학회지
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• 제21권4호
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• pp.263-269
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• 2012

Al doped ZnO(AZO) thin films were deposited at different substrate temperatures by a continuous composition spread(CCS) method. Various compositions of Al doped ZnO thin films deposited at substrate temperatures between 0 and $250^{\circ}C$ were explored to find excellent electrical and optical properties. The AZO thin film deposited at $100^{\circ}C$ had the lowest resistivity, $9{\times}10^{-4}{\Omega}$ cm and its average transmittance at the 400 to 700 nm wavelength region was 92 %. Optimized composition of the AZO thin film which had the lowest resistivity and high transmittance was 3.13 wt% Al doped ZnO.