Studies on structural, optical and electrical characteristics of zirconia thin films grown by pulsed laser deposition at different oxygen partial pressures

We have grown ZrO2 thin films on silicon, sapphire and Pt-Si substrates using pulsed laser deposition by varying oxygen partial pressure in the range ∼1×10−1 to 1×10−5 mbar at a substrate temperature of ∼373K. The influence of oxygen partial pressure on crystal structure, chemical composition, surface morphology, optical and electrical properties of the as grown ZrO2 thin films were investigated. X-ray diffraction studies showed that ZrO2 films grown at ∼1×10−1 and 1×10−5 mbar of oxygen partial pressure were amorphous in nature while monoclinic phase was observed in the range of oxygen partial pressure from ∼1 × 10−2 to 1 × 10−4 mbar with the variation in crystallite size from ∼26 to 10 nm. Atomic force microscopy studies confirmed the nanocrystalline growth of ZrO2 thin films with RMS surface roughness in the range ∼ 2.9 nm to 0.3 nm. For ZrO2 thin films, with decrease in oxygen partial pressure from 1×10−1 to 1×10−5 mbar, we have found a decrease in band gap value from 5.95 to 5.57 eV and an increase in refractive indices value from 1.96 to 2.21 respectively. The leakage current and capacitance of ZrO2 thin films in Pt/ZrO2/Pt capacitive structures were found to increase with decrease in oxygen partial pressure. ZrO2 thin film grown at oxygen partial pressure of 1 × 10−2 mbar showed dielectric constant of ∼48 with low leakage current density of ∼1.3 × 10−3 A/cm2 suitable for storage applications.