SNTEK

Gyeonggi do, South Korea
Gyeonggi do, South Korea
SEARCH FILTERS
Time filter
Source Type

Park H.,Sungkyunkwan University | Jang K.,Sungkyunkwan University | Kumar K.,Sungkyunkwan University | Ahn S.,Sungkyunkwan University | And 6 more authors.
Thin Solid Films | Year: 2011

Cost efficient and large area deposition of superior quality Al 2O3 doped zinc oxide (AZO) films is instrumental in many of its applications, including solar cell fabrication due to its numerous advantages over indium tin oxide (ITO) films. In this study, AZO films were prepared by a highly efficient rotating cylindrical direct current (DC) magnetron sputtering system using an AZO target, which has a target material utilization above 80%, on glass substrates in argon (Ar) ambient. A detailed analysis on the electrical, optical, and structural characteristics of AZO thin films was performed for the solar cell, as well as display applications. The properties of films were found to critically depend on deposition parameters, such as sputtering power, substrate temperature, working pressure, and film thickness. A low resistivity of ∼ 5.5 × 10- 4 Ω cm was obtained for films deposited at 2 kW, keeping the pressure, substrate temperature and thickness constant at 3 mTorr, 230 °C and ~ 1000 nm respectively. This was due to an increase in carrier mobility and large grain size. Mobility is found to be controlled by ionized impurity scattering within the grains, since the mean free path of carriers is much smaller than the grain size of the films. The AZO films showed a high transparency of ~ 90% in the long wavelength region. Our results offer a cost-efficient AZO film deposition method that can fabricate films with significant low resistivity and high transmittance that can be applied in thin-film solar cells, as well as thin film transistor (TFT) and non-volatile memory (NVM). © 2011 Elsevier B.V.


Park J.-H.,Kyung Hee University | Ahn K.-J.,SNTEK | Park K.-I.,SNTEK | Na S.-I.,Korea Institute of Science and Technology | Kim H.-K.,Kyung Hee University
Journal of Physics D: Applied Physics | Year: 2010

We report the characteristics of Al-doped zinc oxide (AZO) films prepared by a highly efficient cylindrical rotating magnetron sputtering (CRMS) system for use as a transparent conducting electrode in cost-efficient bulk hetero-junction organic solar cells (OSCs). Using a rotating cylindrical type cathode with an AZO target, whose usage was above 80%, we were able to obtain a low cost and indium free AZO electrode with a low sheet resistance of ∼4.59 Ω/sq, a high transparency of 85% in the visible wavelength region and a work function of 4.9 eV at a substrate temperature of 230 °C. Moreover, the neutral poly(3,4-ethylenedioxythiophene) : poly(styrenesulfonate) based OSC fabricated on the CRMS-grown AZO electrode at 230 °C showed an open circuit voltage of 0.5 V, a short circuit current of 8.94 mA cm-2, a fill factor of 45% and power conversion efficiency of 2.01%, indicating that CRMS is a promising cost-efficient AZO deposition technique for low cost OSCs. © 2010 IOP Publishing Ltd.


Park J.-H.,Kyung Hee University | Ahn K.-J.,SNTEK | Na S.-I.,Korea Institute of Science and Technology | Kim H.-K.,Kyung Hee University
Solar Energy Materials and Solar Cells | Year: 2011

We report the characteristics of Ga-doped zinc oxide (GZO) films prepared by a highly efficient cylindrical rotating magnetron sputtering (CRMS) system as a function of substrate temperature for use as a transparent conducting electrode in bulk hetero-junction organic solar cells (OSCs). Using a rotating cylindrical GZO target, low sheet resistance (∼11.67 Ω/square) and highly transparent (90%) GZO films were deposited with high usage (∼80%) of the cylindrical GZO target. High usage of the cylindrical GZO target in the CRMS system indicates that CRMS is a promising deposition technique to prepare cost-efficient GZO electrodes for low cost OSCs. Resistivity and optical transmittance of the CRMS-grown GZO film were mainly affected by substrate temperature because the grain size and activation of the Ga dopant were critically dependent on the substrate temperature. In addition, the performance of OSC fabricated on GZO electrode sputtered at 230 °C (11.67 Ω/square) is better than OSC fabricated on as-deposited GZO electrode (29.20 Ω/square). OSCs fabricated on the GZO electrode sputtered at 230 °C showed an open circuit voltage of 0.558 V, short circuit current of 8.987 m A/cm2, fill factor of 0.628 and power conversion efficiency of 3.149%. © 2010 Elsevier B.V. All rights reserved.


Kim H.-K.,Kyung Hee University | Ahn K.-J.,SNTEK | Jang H.,Kyung Hee University | Lee H.,Kyung Hee University
Journal of the Electrochemical Society | Year: 2012

The dependence of electrical, optical, structural, and surface properties on the thickness of Ga-doped ZnO (GZO) thin films deposited on glass substrates by cylindrical rotating magnetron sputtering (CRMS) was investigated. The resistivity of the CMRS-grown GZO films gradually decreased from 7.4×10 -3 Ohm-cm to 4.9×10 -4 Ohm-cm with increasing its thickness, while the transparency of the GZO films in visible region were kept constant regardless of its thickness. Both x-ray diffraction and high resolution electron microscope examinations showed that the CMRS-grown GZO film has a strongly (002) preferred orientation with increasing thickness even though it was sputtered at low substrate temperature below 230°C. By using spectroscopic ellipsometry, we estimated accurately the dielectric function and band gap energy of the CRMS grown GZO film. Using absorption coefficient α(=4πk/λ) and linear extrapolation method, the band gap energy of the CRMS grown GZO film was estimated to be 3.67 × 0.04 eV, which is independent of its thickness. However, we found that it gave erroneous thickness-dependence of band gap energy when we used the absorbance (=-ln(T)/d) derived from transmission rather than the absorption coefficient. © 2011 The Electrochemical Society.

Loading SNTEK collaborators
Loading SNTEK collaborators