Nanoelectrical characterization of ZnO:Al films prepared by spray pyrolysis
Autor
Baron Miranda, Javier Armando
San Juan Hernandez, Samuel
Institución
Resumen
In this work, zinc oxide films with different amounts of aluminum in the precursor solution (0, 0.5, 1, 2, 5 and 10 % [Al/Zn]) were prepared by ultrasonic spray pyrolysis onto glass substrates using zinc acetate as zinc precursor and 450 oC of substrate temperature. The films were characterized by X-ray diffraction, optical transmittance, scanning electron microscopy and current sensing atomic force microscopy. X-ray diffraction indicates a mixture between pure ZnO and some (Zn,Al)O phase with no evidence of crystalline Al2O3. The transmittance maximum and band gap increases with the [Al/Zn} ratio. The morphology was studied by SEM evolves from hexagonal flakes to hexagonal micro columns that first appear included between the flakes and thereafter dominate in the images. AFM indicate a grain size reduction from ZnO to ZnOAl up to 1% [Al/Zn] in the precursor solution as well as an increment in the conductivity, followed by a grain size increase as a reduction in the conductivity. CAFM indicates that conduction changes from grain bulk conduction to conduction through the grain boundaries when [Al/Zn] increases from 0.5-1% to 2-10%. Undoped ZnO shows uneven conduction paths, possibly related with the uneven distribution of vacancies. Financed by SIP20151074 and SIP2015599