• Journal of IKEEE
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• v.24 no.2
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• pp.435-440
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• 2020

ZnO:Al films with about 500 nm thick were prepared by RF magnetron sputtering. The ZnO:Al films were annealed at 100 ℃, 200 ℃, 300 ℃, and 400 ℃ for 10 h, respectively. The resistivity, carrier concentration, and mobility variation of ZnO:Al films with heat treatments were measured. The causes of the resistivity variation of ZnO:Al films with heat treatments were investigated by utilizing the results of x-ray diffraction and field emission scanning electron microscope. The energy band gap, Urbach energy, and refractive index were obtained from the transmittance of ZnO:Al films. The change in electrical properties of the ZnO:Al film was explained in relation to the optical properties.

• Journal of Surface Science and Engineering
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• v.52 no.3
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• pp.145-149
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• 2019

Transparent and conductive ZnO/Ag/SnO2 (ZAS) tri-layer films were deposited onto glass substrates at room temperature by using radio frequency (RF) and direct current (DC) magnetron sputtering. The thickness values of the ZnO and $SnO_2$ thin films were kept constant at 50 nm and the value for Ag interlayer was varied as 5, 10, 15, and 20 nm. In the XRD pattern the diffraction peaks were identified as the (002) and (103) planes of ZnO, while the (111), (200), (220), and (311) planes could be attributed to the Ag interlayer. The optical transmittance and electrical resistivity were dependent on the thickness of the Ag interlayer. The ZAS films with a 10 nm thick Ag interlayer exhibited a higher figure of merit than the other ZAS films prepared in this study. From the observed results, a ZAS film with a 10 nm thick Ag interlayer was believed to be an alternative transparent electrode candidate for various opto-electrical devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1036-1038
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• 2001

The sapphire orientation dependence of the crystallization of ZnO thin films has been studied using real-time synchrotron x-ray scattering. The amorphous ZnO thin films with a 2400-${\AA}$-thick were grown on sapphire(110) and sapphire(001) substrates by radio frequency magnetron sputtering at room temperature. The amorphous ZnO films were crystallization into epitaxial ZnO(002) grains both on the sapphire(110) and on the sapphire(001) substrates. The epitaxial quality, such as mosaic distribution and crystal domain size, of the ZnO grains on the sapphire(110) is high, similar to that of the ZnO grains on the sapphire(001). With increasing the annealing temperature to 600$^{\circ}C$, the mosaic distribution and the crystal domain size of ZnO(002) grains in the film normal direction was improved and decreased, respectively.

• Transactions on Electrical and Electronic Materials
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• v.12 no.1
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• pp.11-15
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• 2011

In this study, $ZnGa_2O_4$ phosphors in its application to field emission displays and electroluminescence were synthesized through the precipitation method and $Mn^{2+}$ ions. A green luminescence activator, $Cr^{3+}$ ions, and a red luminescence activator were separately doped into $ZnGa_2O_4$, which was then screen printed to an indium tin oxide substrate. The thick films of the $ZnGa_2O_4$ were deposited with the various thicknesses using nano-sized powder. The best luminescence characteristics were shown at a thickness of 60 ${\mu}m$. Additionally, green-emission $ZnGa_2O_4:Mn^{2+}$ and red-emission $ZnGa_2O_4:Cr^{3+}$ phosphor thick films, which have superior characteristics, were manufactured through the screen-printing method. These results indicate that $ZnGa_2O_4$ phosphors prepared through the precipitation method have wide application as phosphor of the full color emission.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.445-448
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• 2006

Highly c-axis oriented ZnO thin films were grown on Si(100)substrates with Zn buffer layers. Effects of the Zn buffer layer thickness on the structural and optical qualities of ZnO thin films were investigated using X-ray diffraction (XRD), photoluminescence (PL) and Atomic force microscopy (AFM) analysis techniques. It was confirmed that the quality of a ZnO thin film deposited by rf magnetron sputtering was substantially improved by using a Zn buffer layer. The highest ZnO film quality was obtained with a Zn buffer layer 110 nm thick. The surface roughness of the ZnO thin film increases as the Zn buffer layer thickness increases.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1488-1493
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• 2017

Boron-doped ZnO:Al films were deposited by rf magnetron sputtering. The structural and optical property variations of the films with the boron amounts were studied. ZnO nanorods were grown on $SiO_2/Si$ wafers and glass by a hydrothermal method. ~50 nm-thick boron-doped ZnO:Al films were deposited on the substrates as seed layers. The mixed solution of zinc nitrate hexahydrate and hexamethylenetetramine in DI water was used as a precursor for ZnO nanorods. The concentration of zinc nitrate hexahydrate and that of hexamethylenetetramine were 0.05 mol, respectively. ZnO nanorods were grown at $90^{\circ}C$ for 2 hours. X-ray diffraction was conducted to observe the crystallinity of ZnO nanorods. A field emission scanning electron microscope was employed to study the morphology of nanorods. Optical transmittance was measured by a UV-Vis spectrophotometer, and photoluminescence was carried out with 266 nm light. The ZnO nanorods grown on the 0.5 wt% boron-doped ZnO seed layer showed the best crystallinity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.666-670
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• 2007

Aluminuim doped zinc oxide(ZnO:AL)Films have been prepared on Polyimide(PI) and Coming 7059 glass substrates by r.f. magnetron sputtering method. The structural of the ZnO:Al films were studied in accordance with various deposition R.F power and working pressure by XRD, SEM. And The electrical and optical properties of ZnO:Al films were characterized by Hall effect and UN visible spectrophotometer measurements, ZnO:Al films had were hexagonal wurtzite structure and dominant c-axis orientation. The R.f power and working pressure for optimum condition to fabricate the transparent conductive films using a PI substrate were 2 mTorr and 100W, respectively. The resistivity of the ZnO:Al films prepared under this condition were $9.6{\times}10^{-4}{\Omega}cm$. The optical transmittance of 400nm thick films at 550nm is ${\sim}85 %$.

• Journal of Surface Science and Engineering
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• v.56 no.2
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• pp.147-151
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• 2023

Transparent ZnO (100 nm thick) and ZnO/Ti/ZnO (ZTZ) films were prepared with radio frequency (RF) and direct current (DC) magnetron sputtering on the glass substrate at room temperature. During the ZTZ film deposition, the thickness of the Ti interlayer was varied, such as 6, 9, 12, and 15 nm, while the thickness of ZnO films was kept at 50 nm to investigate the effect of the Ti interlayer on the crystallization and opto-electrical performance of the films. From the XRD pattern, it is concluded that the 9 nm thick Ti interlayer showed some characteristic peaks of Ti (200) and (220), and the grain size of the ZnO (002) enlarged from 13.32 to 15.28 nm as Ti interlayer thickness increased. In an opto-electrical performance observation, ZnO single-layer films show a figure of merit of 1.4×10^-11 Ω^-1, while ZTZ films with a 9 nm-thick Ti interlayer show a higher figure of merit of 2.0×10^-5 Ω^-1.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.161-167
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• 2013

The ZnO thin films were grown on GaN template substrates by RF magnetron sputtering at different RF powers and n-ZnO/p-GaN heterojunction LEDs were fabricated to investigate the effect of the RF power on the characteristics of the n-ZnO/p-GaN LEDs. For the growth of the ZnO thin films, the substrate temperature was kept constant at $200^{\circ}C$ and the RF power was varied within the range of 200 to 500W at different growth times to deposit films of 100 nm thick. The electrical, optical and structural properties of ZnO thin films were investigated by ellipsometry, X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and by assessing the Hall effect. The characteristics of the n-ZnO/p-GaN LEDs were evaluated by current-voltage (I-V) and electroluminescence (EL) measurements. ZnO thin films were grown with a preferred c-axis orientation along the (0002) plane. The XRD peaks shifted to low angles and the surface roughness became non-uniform with an increase in the RF power. Also, the PL emission peak was red-shifted. The carrier density and the mobility decreased with the RF power. For the n-ZnO/p-GaN LED, the forward current at 20 V decreased and the threshold voltage increased with the RF power. The EL emission peak was observed at approximately 435 nm and the luminescence intensity decreased. Consequently, the crystallinity of the ZnO thin films grown with RF sputtering powers were improved. However, excess Zn affected the structural, electrical and optical properties of the ZnO thin films when the optimal RF power was exceeded. This excess RF power will degrade the characteristics of light emitting devices.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.394-401
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• 2009

This paper reports the structural and optical properties of ZnO/glass thin films grown by radio-frequency magnetron sputtering with a powder target. In contrast to ZnO ceramic target typically used, a ZnO raw powder target was sputtered in this study. ZnO grew with the (0002) preferred orientation along the surface normal direction. Initially, the surface of ZnO thin films was flat considerably and then it became rougher as the thickness increased. The optical transmittance was as high as 88% in the range of 400-1000 nm. The bandgap energy of 3.23 eV at the 220 nm thick sample was estimated.