• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.969-972
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• 2004

Al doped Zinc Oxide(ZnO:Al) films, which is widely used as a transparent conductor in optoelectronic devices such as solar cell, liquid crystal display, plasma display panel, thermal heater, and other sensors, were prepared by using the capacitively coupled DC magnetron sputtering method. In this paper the effect of doping amounts of $Al_2O_3$ on the electrical, optical and morphological properties were investigated experimentally, The results show that the structural and electrical properties of the film are highly affected by the doping. The optimum growth conditions were obtained for films doped with 2 wt% of Al203 which exhibit a resistivity of $8.5{\times}10^{-4}{\Omega}-cm$ associated with a transmittance of 91.7 % for 840 nm in film thickness in the wavelength range of the visible spectrum.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.259-264
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• 2009

In this study we investigated the effect of the multi-step texturing process on the electrical and optical properties of hydrogenated Al-doped zinc oxide (HAZO) thin films deposited by rf magnetron sputtering. AZO films on glass were prepared by changing the $H_2/(Ar+H_2)$ ratio at a low temperature of $150^{\circ}C$. The prepared HAZO films showed lower resistivity and higher carrier concentration and mobility than those of non-hydrogenated AZO films. After deposition, the surface of the HAZO films was multi-step textured in diluted HCl (0.5%) for the investigation of the change in the optical properties and the surface morphology due to etching. As a result, the HAZO film fabricated under the type III condition showed excellent optical properties with a haze value of 52.3%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.5
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• pp.1-7
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• 2007

AZO thin films have been fabricated on quartz substrate with various Al doping concentrations and annealing temperatures by sol-gel method. The bset condition of (002) orientation and smooth surface (rms = 1.082 nm) is obtained for the AZO thin film doped with 1 mol % Al and annealed at 550 $^{\circ}C$. The optical transmittance of AZO thin films is higher than 80 % in the visible region. We observe that the energy band gap extends with increasing the Al doping concentration. This phenomenon is due to the Burstein-Moss effect. Through the measurement of Hall effect, it is observed that the AZO thin film has larger carrier concentration and smaller electrical resistivity than the pure ZnO thin film. However, the AZO thin film shows the decrease of carrier concentration and the increase of resistivity with the increase of Al concentration, that is due to the segregation of Al at grain boundaries. The maximum carrier concentration of $1.80{\times}10^{19}\;cm^{-3}$ and the minimum resistivity of 0.84 ${\Omega}cm$ are obtained for the AZO thin film doped with 1 mol % Al and annealed at 550 $^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.5
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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.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.167-167
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• 2005

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.318-324
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• 2007

We report on a strong violet luminescence emitted from the ZnO:Al films grown on glass substrate by radio-frequency magnetron sputtering. The growth of high-quality thin films and their optical properties are controlled by adjusting the mixture ratio of Ar and $O_2$, which is used as the sputtering gas. The crystallinity of the films is improved as the oxygen flow ratio is decreased, as evidenced in both x-ray diffractometer and atomic force microscope measurements. As for the violet luminescence measured by photoluminescence (PL) spectroscopy, the peak energy and intensity of the PL signal are decreased with increasing the oxygen flow ratio. The peak energy of the violet PL spectrum for the thin film with an oxygen flow ratio of 50 % is almost constant, regardless of the increase of laser Power and temperature. These results indicate that the violet PL signal is probably due to defects related to interstitial Zn atoms.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.319.1-319.1
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• 2016

Recently, the Al-doped ZnO (ZnO:Al) films are intensively used in thin film a-Si solar cell applications due to their high transmittance and good conductivity. The textured ZnO:Al films are used to enhance the light trapping in thin film solar cells. The wet etch process is used to texture ZnO:Al films by dipping in diluted acidic solutions like HCl or HF. During that process the glass substrate could be damaged by the acidic solution and it may be difficult to apply it for the inline mass production process since it has to be done outside the chamber. In this paper we report a new technique to control the surface morphology of RF-sputtered ZnO:Al films. The ZnO:Al films are textured with vaporized HF formed by the mixture of HF and H2SiO3 solution. Even though the surface of textured ZnO:Al films by vapor etching process showed smaller and sharper surface structures compared to that of the films textured by wet etching, the haze value was dramatically improved. We achieved the high haze value of 78% at the wavelength of 540 nm by increasing etching time and HF concentration. The haze value of about 58% was achieved at the wavelength of 800 nm when vapor texturing was used. The ZnO:Al film texture by HCl had haze ratio of about 9.5 % at 800 nm and less than 40 % at 540 nm. In addition to low haze ratio, the texturing by HCl was very difficult to control etching and to keep reproducibility due to its very fast etching speed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.466-467
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• 2005

Al doped zinc oxide films (ZnO:Al) were deposited on glass substrate by RF magnetron sputtering from a ZnO target mixed with 2 wt% $Al_2O_3$. The as-deposited ZnO:Al films were rapid-thermal annealed. Electrical properties and structural evolution of the films, as annealed by rapid thermal process (RTP), were studied and compared with the films annealed by conventional annealing process. RTP, the (002) peak intensity increases and the electrical resistivity decreases by 20%, after RT annealing. The effects of RT annealing on the structural evolution and electrical properties of RF sputtered films were further discussed and compared also with the films deposited by DC magnetron sputtering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.303-308
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• 2011

The Gallium-doped ZnO(GZO) film deposited at a temperature of $200^{\circ}C$ and a pressure of 10 mtorr has an optical transmittance of 89.0% and a resistivity of $2.0\;m{\Omega}{\cdot}cm$ because of its high crystallinity. Effect of $Al_2O_3$ oxide buffer layers on the optical and electrical properties of sputtered ZnO films were intensively investigated for developing the electrodes of opto-electronic devices which demanded high optical transmittance and low resistivity. The use of $Al_2O_3$ buffer layer could increase optical transmittance of GZO film to 90.7% at a wavelength of 550 nm by controlling optical spectrum. Resistivity of deposited GZO films were much dependent on the deposition condition of $O_2/(Ar+O_2)$ flow rate ratio during the buffer layer deposition. It is considered that the $Al_2O_3$ buffer layer could increase the carrier concentration of the GZO films by doping effect of diffused Al atoms through the rough interface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.41-41
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• 2008

Al-doped ZnO (AZO) thin films have been fabricated by vertical in-line dc magnetron sputtering for transparent conducting oxides (TCOs) applications. The effects of substrate temperature and dc power on the characteristics of AZO thin films are investigated and also optimized the process conditions to get the best electrical and optical properties. The fabricated thin films show a good electrical and optical uniformity within ${\pm}5%$ over the whole area of substrate ($200mm\;{\times}\;200mm$) ; the minimum resistivity of $8\;{\times}\;10^{-4}\;{\Omega}cm$ and the average transmittance of 90% within the visible wavelength range. We have found that the band gap ($E_g$) increases with increasing substrate temperature and dc power, whereas the crystallinity is getting improved with increasing substrate temperature. The binding energy of Zn $2p_{3/2}$ and O 1s is observed to decrease as the substrate temperature increases.