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Al-Doped ZnO Films Deposited on Flexible Substrates by RF Sputtering for Thin Film Solar Cells
S. Fernández, A. Martínez-Steele, J.J. Gandía, F.B. Naranjo
Magnetron Sputtering, Flexible Substrate, Zinc Oxide
Thin Films
Subtopic: Amorphous and Microcrystalline Silicon
Event: 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain
Session: 3AV.1.59
2347 - 2351
ISBN: 3-936338-24-8
Paper DOI: 10.4229/23rdEUPVSEC2008-3AV.1.59
0,00 EUR
Document(s): paper


Transparent conducting aluminium-doped zinc oxide (ZnO:Al) films have been prepared on polyethylene terephthalate (PET) and Corning 7059 substrates by radio-frequency (RF) magnetron sputtering at low temperature (100 ºC). In this work, the optimization of the sputtering parameters such as RF power and working pressure was performed in order to achieve films with both low resistivity values and high average transmittance in the visible wavelength. The XRD measurements revealed that all the obtained films were polycrystalline with a preferred orientation with the c-axis perpendicular to the substrate. Besides, regardless the substrate, the ZnO:Al films were increasingly dark gray coloured as the RF power increased, resulting in a loss of transmittance. These metallic surfaces were obtained at lower RF power values on the polymer substrate in comparison with the glass substrate. High quality films on PET with resistivities as low as 1.1 x 10-3 Ω-cm and average transmittance around 80 % were obtained by suitable controlling the sputtering parameters, 75 W and 1.5 mTorr. On the other hand, it was found that the best films on glass substrate with a resistivity low as 6.2 x 10-4 Ω-cm and an average transmittance around 85 % at the visible wavelength range were obtained at 125 W and 1.5 mTorr. These obtained results showed that the structural, optical and electrical quality of the samples deposited on polymer substrates was similar than those on glass substrates. This would suggest that high quality ZnO:Al films can be obtained on polymer substrates, opening a new field of low cost, light weight, small volume, flexible and unbreakable large area photovoltaic devices.