Antiferroelectric titanium-doped zirconia thin films deposited via HiPIMS for highly efficient electrocaloric applications

Abstract In this study, the antiferroelectric (AFE) and electrocaloric (EC) characteristics of lead-free titanium (Ti)-doped zirconia (ZrO2) thin films deposited via high-power impulse magnetron sputtering (HiPIMS) were investigated. The argon-to-oxygen ratio was initially optimized during deposition to obtain a more stoichiometric ZrO2 film for enhanced antiferroelectricity. Furthermore, enhanced crystallinity was achieved through the incorporation of Ti atoms into ZrO2 thin films as confirmed via grazing incidence X-ray diffraction and high-resolution transmission electron microscopy. For metal-insulator-metal capacitors with Ti-doped ZrO2 thin films, the AFE behaviors were significantly improved because of the excellent crystallinity of the tetragonal phase. Based on a fast polarization response and robust fatigue resistance under a 106-cycle endurance test, the EC effect was successfully explored, and an adiabatic temperature change (ΔT) of -14.8 K was realized. With competitive EC properties, Ti-doped ZrO2 thin films deposited via HiPIMS are proposed as promising candidates for use in future cooling systems.