• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.351.2-351.2
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• 2014

Indium tin oxide (ITO) has a lot of variations of its properties because it is basically in an amorphous state. Therefore, the differences in composition ratio of ITO can result in alteration of electrical properties. Normally, ITO is considered as transparent conductive oxide (TCO), possessing excellent properties for the optical and electrical devices. Quantitatively, TCO has transparency over 80 percent within the range of 380nm to 780nm, which is visible light although its specific resistance is less than $10-3{\Omega}/cm$. Thus, the solar cell is the best example for which ITO has perfectly matching profile. In addition, when ITO is used as transparent conductive electrode, this material essentially has to have a proper work function with contact materials. For instance, heterojunction with intrinsic thin layer (HIT) solar cell could have both front ITO and backside ITO. Because each side of ITO films has different type of contact materials, p-type amorphous silicon and n-type amorphous silicon, work function of ITO has to be modified to transport carrier with low built-in potential and Schottky barrier, and approximately requires variation from 3 eV to 5 eV. In this study, we examine the change of work function for different sputtering conditions using ultraviolet photoelectron spectroscopy (UPS). Structure of ITO films was investigated by spectroscopic ellipsometry (SE) and scanning electron microscopy (SEM). Optical transmittance of the films was evaluated by using an ultraviolet-visible (UV-Vis) spectrophotometer

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.425-425
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• 2008

The transparent conducting oxides(TCOs) are widely used as electrodes for most flat panel display devices(FPDs), electrodes in solar cells and organic light emitting diodes(OLED). Among them, indium oxide materials are mostly used due to its high electrical conductivity and a high transmittance in the visible spectrum. The present study reports on a study of the electrical and optical properties of IGZO thin films prepared on glass and PET substrates by the combinational magnetron sputtering. We use the targets of IZO and Ga2O3 for the deposition process. In some case the deposition process is coupled with the End-Hall ion-beam treatment onto the substrates before the sputtering. In addition we control the deposition rate to optimize the film quality and to minimize the surface roughness. Then we investigate the effects of the Ar gas pressure and RF power during the sputtering process upon the electrical, optical and morphological properties of thin films. The properties of prepared IGZO thin films have been analyzed by using the XRD, AFM, a-step, 4-point probe, and UV spectrophotometer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.738-746
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• 2004

Recently zinc oxide(ZnO) has emerged as one of the most promising transparent conducting films with a strong demand of low cost and high performance optoelectronic devices, ZnO film has many advantages such as high chemical and mechanical stabilities, and abundance in nature. In this paper, in order to obtain the excellent transparent conducting film with low resistivity and high optical transmittance for Plasma Display Pannel(PDP), aluminium doped zinc oxide films were deposited on Corning glass substrate by dc magnetron sputtering method. The effects of the discharge power and doping amounts of $Al_2$$O_3$ on the electrical and optical properties were investigated experimentally. Particularly in order to lower the electrical resistivity, positive and negative bias voltages were applied on the substrate, and the effect of bias voltage on the electrical properties of ZnO:Al thin film were also studied and discussed. Films with lowest resistivity of $4.3 \times 10 ^{-4} \Omega-cm$ and good transmittance of 91.46 % have been achieved for the films deposited at 1 mtorr, $400^{\circ}C$, 40 W, Al content of 2 wt% with a substrate bias of +30 V for about 800 nm in film thickness.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.357-362
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• 2007

AZO(Aluminum-doped Zinc Oxide) films are attractive materials as transparent conductive electrode because they are inexpensive, nontoxic and abundant element compared with ITO(Indium Tin Oxide). AZO films have been deposited on glass (corning 1737) substrates by RF magnetron sputtering. The AZO film was post-annealed at $600^{\circ}C$ for 2 hr with $N_2$ atmosphere. The AZO films were used as an anode contact to fabricate OLEDs(Organic Light Emitting Diodes). OLEDs with $AZO/TPD/Alq_3/Al$ configuration were fabricated by thermal evaporation. We investigated that the electric, structural and optical properties of AZO thin films, which measured using the methods of XRD, SEM, Hall measurement and Spectrophotometer. The current density-voltage and luminescence-voltage properties of devices were studied and compared with ITO devices fabricated under the same conditions.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.121-124
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• 2016

ZnSnO₃ (ZTO)/Ag/ ZnSnO₃ (ZTO) trilayer films were prepared on glass substrates by radio frequency (RF) and direct current (DC) magnetron sputtering. The electrical resistivity and optical transmittance of the films were investigated as a function of the Ag interlayer thickness. ZTO films with a 15 nm thick Ag interlayer show the highest average visible transmittance (83.2%) in the visible range. In this study, the highest figure of merit (2.1×10⁻² Ω cm) is obtained with the ZTO 50 nm/Ag 15 nm/ZTO 50 nm films. The enhanced optical and electrical properties of ZTO films with a 15 nm thick Ag interlayer are attributed to the crystallization of the Ag interlayer, as supported by the distinct XRD pattern of the Ag (111) peaks. From the observed results, higher optical and electrical performance of the ZTO film with a 15 nm thick Ag interlayer seems to make a promising alternative to conventional transparent conductive ITO films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.10-10
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• 2009

Transparent BNO thin films were grown on Al-doped ZnO (AZO)/Ag/AZO/polyethersulfon (PES) (abbreviated as AAAP) transparent electrodes at a low temperature by the NCD technique. The BNO films grown on the crystallized AZO/Ag/AZO (AAA) electrodes exhibit an amorphous phase with a root mean square (rms) roughness of approximately 2 nm in the range of deposition temperature. The capacitors (Pt/BNO/AAAP) with BNO films grown at $100^{\circ}C$ show a dielectric constant of 24 and dissipation factor of 8% at 100 kHz, a leakage current density of about $8{\times}10^{-6}A/cm^2$ at an applied voltage of 1.0V. The optical transmittances of the BNO/AAAP exhibited above 80% at wavelength of 550nm at all of deposition temperature. The mechanical stability of the BNO/AAA as well as AAA electrode with the PES substrates through the bending was ensured for flexible electronic device applications. The transparent BNO capacitors grown on AAAP are powerful candidate for integration with the transparent solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.3
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• pp.165-170
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• 2018

In this study, double-layered TCO (transparent conductive oxide) films were produced by depositing two distinct TCO materials: $SnO_2$ works as an n-type layer and ITO (indium-doped tin oxide) serves as a transparent conductor. Both transparent conductive oxide-films were sequentially deposited by sputtering. The electrical and optical properties of single-layered TCO films ($SnO_2$) and double-layered TCO ($ITO/SnO_2$) films were investigated. A TCO-embedding photodetector was realized through the formation of an $ITO/SnO_2/p-Si/Al$ layered structure. The remarkably high rectifying ratio of 400.64 was achieved with the double-layered TCO device, compared to 1.72 with the single-layered TCO device. This result was attributed to the enhanced electrical properties of the double-layered TCO device. With respect to the photoresponses, the photocurrent of the double-layered TCO photodetector was significantly improved: 1,500% of that of the single-layered TCO device. This study suggests that, due to the electrical and optical benefits, double-layered TCO films are effective for enhancing the photoresponses of TCO photodetectors. This provides a useful approach for the design of photoelectric devices, including solar cells and photosensors.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.17-21
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• 2012

Ga-doped ZnO (GZO) thin films for application as transparent conducting oxide film were deposited on the glass substrate by using rf-magnetron sputtering system. The effects of working pressure on electrical and optical characteristics of GZO films were investigated. Regardless of the working pressure, all films were oriented along with the c-axis, perpendicular to the substrate. The electrical resistivity was about $8.68{\times}10^{-3}{\Omega}{\cdot}cm\sim2.18{\times}10^{-3}{\Omega}{\cdot}cm$ and the average transmittance of all films including substrates was over 90% in the visible range. The good transparents and conducting properties were obtained due to controle the working pressure. The obtained results have acceptable for application as transparent conductive electrodes in LCDs and solar cells.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1351_1352
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• 2009

We deposited $SnO_2$:F thin films by atomospheric pressure chemical vapor deposition(APCVD) on corning glass. $SnO_2$:F films were used as transparent conductive oxide (TCO) electrode for Si thin film solar cells. We have investigated structural, electrical and optical properties of $SnO_2$:F thin films and fabricated thin film Si solar cells by plasma enhanced CVD(PECVD) on $SnO_2$:F thin films The cells were characterized by I-V measurement using AM1.5 spectra. Conversion efficiency of our cells were between 5.61% and 6.45%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.789-794
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• 2008

Zinc oxide (ZnO) has been widely studied for its practical applications such as transparent conduction electrodes for flat panel displays and solar cells. Especially, ZnO films show good chemical stability against hydrogen plasma, absence of toxicity, abundance in nature, and then suitable for photovoltaic applications. However, the fabrication process of thin film solar cells require a high substrate temperature and/or post heat treatment. Therefore, the layers have to withstand high temperatures, requiring an excellent stability without degrading their electronic and optical properties. In this paper, we investigated the stability of zinc oxide (ZnO) films doped with aluminum and hydrogen. Doped ZnO films were prepared by r.f. magnetron sputter and followed by heat treatment at different temperatures and for various times.