Electrical properties of zinc oxide sputtered thin films
Résumé
ZnO thin films were deposited on silicon substrate by rf magnetron sputtering from metallic zinc target. The electrical properties of ZnO are currently being studied. In this work, measurements of the ac conductivity properties of ZnO sandwich structures with silver and platinum electrodes are reported. The frequency dependence of both the ac conductivity and dielectric constant of thin films of ZnO have been investigated in the frequency range 5 kHz- 13 MHz. It is shown that the total ac conductivity σ(ω), obeys the equation σ(ω) = AωS where s is an index which increases with frequency and decreases with temperature. It appears that for ZnO films, the conduction mechanism is thermally activated and both the overlap large polaron tunnelling and the correlated barrier-hopping of charge carrier over localized states fit the experimental data. The dielectric constant, εr, lies in the range 8-9 at room temperature and is independent of the frequency in the dielectric thin films.
Mots clés
Tunnel effect
Polaron
Thermal activation
Thermostimulated conduction
MHz range
Permittivity
Frequency dependence
Sandwich compound
Alternating current
Electrical conductivity
Measurement method
Magnetron
Radiofrequency sputtering
Dielectric properties
Sputtered materials
Zinc oxide
Thin film
Electrical properties
Waveform
Experimental result
Frequency characteristic
Thermal characteristic
Dielectric thin films
Room temperature
Experimental data
Localized state
Charge carrier