Effect of sputtering power on the electrical and optical properties of Ca-doped ZnO thin films sputtered from nanopowders compacted target

•Ca-doped ZnO films grown by rf-magnetron on glass substrates.•(40–100W) CZO films grown by rf-magnetron on glass substrates.•Transmittance up to 85% in visible region, sharp absorption edge at 380nm.•Blue shift of optical band gap: Eg=3.30eV for rf=60W and d=400nm; Egmax=3.49eV for rf=100W.•Good ph...

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Bibliographic Details
Published in:Optical materials 2015-07, Vol.45, p.97-103
Main Authors: Mahdhi, H., Ben Ayadi, Z., Gauffier, J.L., Djessas, K., Alaya, S.
Format: Article
Language:English
Subjects:
Ca-doped ZnO
Engineering Sciences
Optical properties
Sol–gel growth
Sputtering
Thin films
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Summary:•Ca-doped ZnO films grown by rf-magnetron on glass substrates.•(40–100W) CZO films grown by rf-magnetron on glass substrates.•Transmittance up to 85% in visible region, sharp absorption edge at 380nm.•Blue shift of optical band gap: Eg=3.30eV for rf=60W and d=400nm; Egmax=3.49eV for rf=100W.•Good physical properties suited for films integration in optoelectronic devices. In the present work, we have deposited calcium doped zinc oxide thin films by magnetron sputtering technique using nanocrystalline particles elaborated by sol–gel method as a target material. In the first step, the nanoparticles were synthesized by sol–gel method using supercritical drying in ethyl alcohol. The structural properties studied by X-ray diffractometry indicates that Ca doped ZnO has a polycrystalline hexagonal wurzite structure with a grain size of about 30nm. Transmission electron microscopy (TEM) measurements have shown that the synthesized CZO is a nanosized powder. Then, thin films were deposited onto glass substrates by rf-magnetron sputtering at ambient temperature. The influence of RF sputtering power on structural, morphological, electrical, and optical properties were investigated. It has been found that all the films deposited were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. They have a typical columnar structure and a very smooth surface. The as-deposited films show a high transmittance in the visible range over 85% and low electrical resistivity at room temperature.
ISSN:0925-3467
1873-1252
DOI:10.1016/j.optmat.2015.03.015