• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1281-1282
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• 2008

Low cost TCO(Transparent Conductive oxide) thin films were prepared by 3" DC/RF magnetron sputtering systems. For the AZO preparation processes a 99.99% AZO target (Zn: 98 wt.%, $Al_2O_3$: 2 wt.%) was used. In order to verify feasibility of the AZO thin films to organic light emitting device (OLED) application, test organic light emitting device was fabricated based on AZO as TCO, TPD as hole transporting layer (HTL), Alq3 as both emitting layer (EML) and electron transporting layer (ETL), and aluminium as cathode, where the both ITO and AZO surfaces were treated using $O_2$ RF plasma. The I-V characteristics of the AZO/TPD/Alq3/Al OLEDs were evaluated. As the results, the performance of the OLEDs with AZO as transparent conducting anode could be useable.

• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.461-465
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• 2011

An aluminum doped zinc oxide (AZO) film for front contacts of thin film solar cells, in this work, were deposited by r.f. magnetron sputtering, and then etched in diluted hydrochloric acid solution for different times. Effects of surface texturing on the electro-optical properties of AZO films were investigated. Also, to clarify the light trapping of textured AZO film, amorphous silicon thin film solar cells were fabricated on the textured AZO/glass substrate and the performance of solar cells were studied. After texturing, the spectral haze at the visible range of 400 ~750 nm increased substantially with the etching time, without a change in the resistivity. The conversion efficiency of amorphous Si solar cells with textured AZO film as a front electrode was improved by the increase of short-circuit current density ($J_{sc}$), compared to cell with flat AZO films.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.1
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• pp.50-55
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• 2008

AI-doped ZnO(AZO) thin films have been fabricated on glass substrate by sol-gel method, and the effect of Al precursors and post-annealing temperature on the characteristics of AZO thin films was investigated. The sol was prepared with zinc acetate, EtOH, MEA and Al precursors. In order to dope Al in ZnO, two types of aluminum nitrate and aluminum chloride were used as Al precursor. Zinc concentration was 0.5 mol/l and the content of Al precursor was 1 at% of Zn in the sol. The sol was spin-coated on glass substrate, and the coated films were annealed at 550ue for 2 hand were post-annealed at temperature ranges of $300{\sim}500^{\circ}C$ for 2 h in reducing atmosphere ($N_2/H_2$= 9/1). Structural, electrical and optical propertis of the fabricated AZO thin films were analyzed by XRD, FE-SEM, AFM, hall effect measurement system and UV-visible spectroscopy. Optical and electrical properties of AZO thin films prepared with aluminum nitrate as Al precursor were better than those of films prepared with aluminum chloride. The electrical resistivity and the optical transmittance of films decreased with increasing post-annealing temperatures. The minimum electrical resistivity of $2{\times}10^{-3}$ and the maximum optical transmittance of 91% were obtained for the AZO thin films post-annealed at $550^{\circ}C\;and\;300^{\circ}C$, respectively.

• Industry Promotion Research
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• v.1 no.1
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• pp.1-6
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• 2016

To research the correlation between the amorphous and crystal structure of oxide semiconductors, AZO and IGZO films were deposited and annealed with various temperatures in a vacuum state. AZO increased the degree of crystal structure with increasing the annealing temperature, but IGZO became an amorphous structure after the annealing process at high temperature. The series of AZO films with various annealing temperatures showed the chemical shift from the analyzer of PL and O 1s spectra, but the results of IGZO films by PL and O 1s spectra were not observed the chemical shift. The binding energy of oxygen vacancy of AZO with a crystal structure was 531.5 eV, and that of IGZO with an amorphous structure was 530 eV as a lower binding energy.

• Transactions on Electrical and Electronic Materials
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• v.11 no.1
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• pp.29-32
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• 2010

In this study, transparent and conductive Al-doped zinc oxide (AZO) films were prepared on a glass substrate by an radio frequency (RF) magnetron sputtering method using a 150-nm-thick AZO target (Al: 2 wt.%) at room temperature. We investigated the effects of RF power between 100-350 W (in steps of 50 W) on the structural, electrical, and optical properties of the AZO films. The thickness and cross-sectional images of the films were observed by field emission scanning electron microscopy. The thicknesses of all films were kept constant at 150 nm and grown on a glass substrate. The grain sizes of the AZO films were determined with the X-ray diffraction by using the Scherrer' equation, and their electrical properties were investigated using a Hall effect electronic transport measurement system. The transmittance of the AZO films was also measured by an ultraviolet-visible spectrometer.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.32-36
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• 2018

For various oxygen($O_2$) to argon(Ar) gas ratio, aluminum-doped zinc oxide(AZO) films were deposited for 3 min at different duty ratio by changing reverse pulse times. As the duty ratio increased, the thickness of the AZO film decreased and the sheet resistance increased. It can be concluded that When sputtering AZO Thin film, oxygen interfered with sputtering. When the reverse time was increased, the thickness of AZO was proportional to the real sputtering time and decreased. From the optical transmittance and sheet resistance, it was possible to obtain a higher figure of merits of AZO at a lower reverse pulse time. Even at the short reversed pulse time, it can be concluded that the accumulated charges on the AZO target are completely cleared. At a lower reverse pulse time, pulsed-DC sputtering of AZO is expected to be used instead of DC sputtering in the deposition of transparent conductive oxide(TCO) films without any degradation in thickness and structural/electrical characteristics.

• Journal of the Korean institute of surface engineering
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• v.42 no.6
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• pp.267-271
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• 2009

Multicomponent transparent conducting oxide films were deposited on glass substrates at 150 by dual magnetron sputtering of AZO and ITO targets. In the case of mixing a limited amount of ITO (10W), resistivity of TCO films was significantly increased compared to the AZO film; from $3.5{\times}10^{-3}$ to $9.7{\times}10^{-3}{\Omega}{\cdot}cm$. Deterioration of the electrical conductivity is attributed to the decreases in carrier concentration and Hall mobility. Improvement of the conductivity could be obtained for the films prepared with ITO powers larger than 40 W. The lowest resistivity ($\rho$) of $7.3{\times}10^{-4}{\Omega}{\cdot}cm$ was achieved when ITO power was 100 W. Effects of $H_2$ incorporation on the electrical and optical properties of AZO-ITO films were investigated in this work. Addition of small amount of hydrogen resulted in the increase of carrier concentration and the improvement of electrical conductivity. It is apparent that the roughness of AZO-ITO films decreases dramatically after the transition of microstructure from polycrystalline to amorphous phase, which gives practical advantages such as an excellent uniformity of surface and a high etching rate. AZO-ITO films grown at sputtering ambient with hydrogen gas are expected to be applicable to optoelectronic devices such as organic light emitting diodes and flexible displays due to their sufficient electrical and structural properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.10
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• pp.652-657
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• 2015

We have investigated the properties of Al-doped ZnO (AZO) thin films as functions of atomic layer deposition (ALD) oxidants. AZO transparent conducting oxides (TCOs) layer was deposited by ALD with adding trimethylaluminum (TMA) and diethylzinc (DEZn). AZO films were deposited at low temperature with $H_2O$ and $O_3$ as oxidants. Electrical, optical and structural properties of AZO thin films were investigated by 4-point probe, Hall effect measurement, UV-VIS, and AFM. Microstructure and atomic bonding states were investigated by HRXRD and XPS. The resistivity of AZO films grown using $H_2O$ was lower than the films grown using $H_2O$ and $O_3$, by approximately two orders of magnitude. The differences in oxygen vacancy peak intensity of AZO films were correlated to the optical and electrical properties.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.889-894
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• 2001

2wt% $Al_2O_3-doped$ ZnO (AZO) thin films were deposited on sapphire (0001) single crystal substrate by parellel type rf magnetron sputtering at 55$0^{\circ}C$. The as-grown AZO thin films was polycrystalline and showed only broad deep defect-level photoluminescence (PL). In order to examine the change of PL property, AZO thin films were annealed in $N_2$ (N-AZO) and $H_2$ (H-AZO) at the temperature of $600^{\circ}C$~$1000^{\circ}C$ through rapid thermal annealing. After annealed at $800^{\circ}C$, N-AZO shows near band edge emission (NBE) with very small deep-level emission, and then N-AZO annealed at $900^{\circ}C$ shows only sharp NBE with 219 meV FWHM. In Comparison with N-AZO, H-AZO exhibits very interesting PL features. After $600^{\circ}C$ annealing, deep defect-level emission was quire quenched and NBE around 382 nm (3.2 eV) was observed, which can be explained by the $H_2$passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emission was firstly observed in AZO thin films. Moreover, peculiar PL peak around 694 nm (1.78 eV) is also firstly observed in all the H-AZO thin films and this is believed good evidence of hydrogenation of AZO. Based on defect-level scheme calculated by using the full potential linear muffin-tin orbital (FP-LMTO), the emission 3.2 eV, 3.05 eV, 3.84 eV and 1.78 eV of H-AZO are substantially deginated as exciton emission, transition from conduction band maximum to $V_{ Zn},$ from $Zn_i$, to valence band maximum $(V_{BM})$ and from $V_{o} to V_BM}$, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.15-20
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• 2010

In this study, AZO (Al: 3 wt%) thin films have been prepared on PES Plastic substrates at various working pressure (5~20 mTorr), $O_2$ gas flow rate(0~3%) and the fixed substrate temperature of 200 f by using the RF magnetron sputtering and their optical and electrical properties have been studied. The XRD measurement shows that AZO thin films exhibit c-axis preferred orientation. From the results of AFM measurements, it is known that the lowest surface roughness (3.49 nm) is obtained for the AZO thin film fabricated at 5 mTorr of working pressure and 3% of $O_2$ gas flow rate. The optical transmittance of AZO thin films is measured as 80% in the visible region. We observe that the energy band gap of AZO thin films increases with decreasing the working pressure and the $O_2$ gas flow rate. This phenomenon is due to the Burstein-Moss effect. Hall measurement shows that the maximum carrier concentration ($2.63\;{\times}\;10^{20}\;cm^{-3}$) and the minimum resistivity ($4.35\;{\times}\;10^{-3}\;{\Omega}cm$) are obtained for the AZO thin film fabricated at 5mTorr of working pressure and 0% of $O_2$ gas flow rate.