Suigen, South Korea
Suigen, South Korea

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Cheon D.,Changwon National University | Ahn K.-J.,SNTEK Co. | Lee W.,Changwon National University
Korean Journal of Materials Research | Year: 2017

To establish low-temperature process conditions, process-property correlation has been investigated for Ga-doped ZnO (GZO) thin films deposited by pulsed DC magnetron sputtering. Thickness of GZO films and deposition temperature were varied from 50 to 500 nm and from room temperature to 250 °C, respectively. Electrical properties of the GZO films initially improved with increase of temperature to 150°C, but deteriorated subsequently with further increase of the temperature. At lower temperatures, the electrical properties improved with increasing thickness; however, at higher temperatures, increasing thickness resulted in deteriorated electrical properties. Such changes in electrical properties were correlated to the microstructural evolution, which is dependent on the deposition temperature and the film thickness. While the GZO films had c-axis preferred orientation due to preferred nucleation, structural disordering with increasing deposition temperature and film thickness promoted grain growth with a-axis orientation. Consequently, it was possible to obtain a good electrical property at relatively low deposition temperature with small thickness. © Materials Research Society of Korea, All rights reserved.


Song A.,Dongguk University | Park H.-W.,Dongguk University | Vishwanath S.K.,Kongju National University | Kim J.,Kongju National University | And 3 more authors.
Ceramics International | Year: 2016

Transparent conducting properties of molybdenum doped indium oxide thin films by polymer-assisted solution (PAS) were investigated as a function of Mo doping concentration. Indium oxide films with molybdenum of ~1.5% (MIO) showed lowest electrical resistivity with . 7.89×10-4Ωcm, compared to those of indium oxide films with . 4.39×10-3Ωcm. The enhancement of the transparent conducting properties by molybdenum doping were explained by the electronic structure in terms of chemical bonding states, band edge states below the conduction band, and band alignment. Molybdenum doping into indium oxide films resulted in the evolution of the conduction band and the change of band alignment. © 2016 Elsevier Ltd and Techna Group S.r.l.


Kar J.P.,Yonsei University | Kim S.,Yonsei University | Shin B.,Yonsei University | Park K.I.,SNTEK Co. | And 4 more authors.
Solid-State Electronics | Year: 2010

Al-doped ZnO (AZO) films were deposited on glass substrates by pulsed DC sputtering technique with various working pressures in the range of 1-15 mTorr. A relationship between the morphological, mechanical and electrical properties of sputtered AZO films was studied as a function of sputtering pressure. The sputtered films were highly c-axis oriented. The n-type conductivity in AZO films was observed due to the substitutional doping of Al. AZO films deposited at 3 mTorr have shown an electrical resistivity of 2.2 × 10-4 Ω cm and high transmittance in visible range with better mechanical properties. For higher sputtering pressures an increase in the resistivity was observed due to a decrease in the mobility and the carrier concentration. The lower sputtering pressure was found suitable for the fabrication of low-cost transparent conductive oxide layer for futuristic electronic devices. © 2010 Elsevier Ltd. All rights reserved.


Kim D.-S.,Yonsei University | Park J.-H.,Yonsei University | Lee S.-J.,Yonsei University | Ahn K.-J.,SNTEK Co. | And 4 more authors.
Materials Science in Semiconductor Processing | Year: 2013

The effect of oxygen concentration on the properties of Al-doped ZnO (AZO) transparent conductive films has been investigated on the films deposited by pulsed DC magnetron sputtering using a cylindrical ZnO target containing 2 wt% Al. AZO films were deposited at 230 °C to the thickness of about 1000 nm and the oxygen concentration was controlled by varying the O2/Ar supply ratio from 0 to 0.167. With the increasing O2/Ar ratio, crystallinity of the AZO films deteriorated while the film surface became smooth. Accompanying this, electrical properties also deteriorated significantly. When the O2/Ar ratios were 0 and 0.033, the AZO films showed metallic conduction behavior with the electrical resistivity in the mid 10-4 Ω cm range. However, when the ratios were 0.100 and 0.167, the films showed poor electrical conduction behavior similar to semiconductors as deduced from the transmittance behavior. Spectroscopic analysis showed that such deteriorating properties are due to the formation of condensed oxide group through the reaction between excess oxygen and dopant aluminum. © 2013 Elsevier Ltd. All rights reserved.


Shin B.-K.,Yonsei University | Lee T.-I.,Yonsei University | Park J.-H.,Yonsei University | Park K.-I.,SNTEK Co. | And 4 more authors.
Applied Surface Science | Year: 2011

Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs. © 2011 Elsevier B.V. All rights reserved.


Shin B.-K.,Yonsei University | Lee T.-I.,Yonsei University | Park K.-I.,SNTEK Co. | Ahn K.-J.,SNTEK Co. | Myoung J.-M.,Yonsei University
Korean Journal of Materials Research | Year: 2010

Various thicknesses of Al-doped ZnO (AZO) films were deposited on glass substrate using pulsed dc magnetron sputtering with a cylindrical target designed for large-area high-speed deposition. The structural, electrical, and optical properties of the films of various thicknesses were characterized. All deposited AZO films have (0002) preferred orientation with the c-axis perpendicular to the substrate. Crystal quality and surface morphology of the films changed according to the film thickness. The samples with higher surface roughness exhibited lower Hall mobility. Analysis of the measured data of the optical band gap and the carrier concentration revealed that there were no changes for all the film thicknesses. The optical transmittances were more than 85% regardless of film thickness within the visible wavelength region. The lowest resistivity, 4.13 × 10-4 Ω ·cm-1, was found in 750 nm films with an electron mobility (μ) of 10.6 cm2V-1s-1 and a carrier concentration (n) of 1.42 × 1021 cm-3.


Kim K.,Korea Institute of Industrial Technology | Kim D.,SNTEK Co. | Ahn K.-J.,SNTEK Co. | Jeong C.,Korea Institute of Industrial Technology
Journal of Nanoscience and Nanotechnology | Year: 2016

Cu(In,Ga)S2 (CIGS) absorbers were prepared using two-step process. Cu-In-Ga precursors were deposited by sputtering method and then were sulfurized by rapid thermal process based on H2S gas. Sulfurization temperature was changed from 470 °C to 510 °C. As the processing temperature increased, larger grains and denser absorbers were observed. The polycrystalline chalcopyrite structure of CuInGaS2 was shown in all samples, and their XRD peak was dominantly observed at (112) direction. CIGS thin film solar cells were fabricated with wide-bandgap absorbers obtained by varying sulfurization temperature. The best efficiency was shown with the processing temperature of 490 °C and 8.93% with 1.507 eV of wide optical bandgap. Copyright © 2016 American Scientific Publishers All rights reserved.

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