33 research outputs found
High Electrocaloric Effect in Lead Scandium Tantalate Thin Films with Interdigitated Electrodes
No full textLead scandium tantalate, Pb(Sc,Ta)O(3), is an excellent electrocaloric material showing large temperature variations, good efficiency, and a broad operating temperature window. In form of multilayer ceramic capacitors integrated into a cooling device, the device can generate a temperature difference larger than 13 K. Here, we investigate Pb(Sc,Ta)O(3) in form of thin films prepared using the sol–gel chemical solution deposition method. We report the detailed fabrication process of high-quality films on various substrates such as c-sapphire and fused silica. The main originality of this research is the use of interdigitated top electrodes, enabling the application of very large electric fields in PST. We provide structural and electrical characterisation, as well as electrocaloric temperature variation, using the Maxwell relation approach. Films do not show a B-site ordering. The temperature variation from 7.2 to 15.7 K was measured on the Pb(Sc,Ta)O(3) film on a c-sapphire substrate under the electric field of 1330 kV/cm between 14.5 °C and 50 °C. This temperature variation is the highest reported so far in Pb(Sc,Ta)O(3) thin films. Moreover, stress seems to have an effect on the maximum permittivity temperature and thus electrocaloric temperature variation with temperature in Pb(Sc,Ta)O(3) films. Tensile stress induced by fused silica shifts the “transition” of Pb(Sc,Ta)O(3) to lower temperatures. This study shows the possibility for electrocaloric temperature variation tuning with stress conditions
Transparent Ferroelectric Capacitors on Glass
No full textWe deposited transparent ferroelectric lead zirconate titanate thin films on fused silica and contacted them via Al-doped zinc oxide (AZO) transparent electrodes with an interdigitated electrode (IDE) design. These layers, together with a TiO2 buffer layer on the fused silica substrate, are highly transparent (>60% in the visible optical range). Fully crystallized Pb(Zr0.52Ti0.48)O3 (PZT) films are dielectrically functional and exhibit a typical ferroelectric polarization loop with a remanent polarization of 15 μC/cm2. The permittivity value of 650, obtained with IDE AZO electrodes is equivalent to the one measured with Pt electrodes patterned with the same design, which proves the high quality of the developed transparent structures
Low temperature growth of piezoelectric AlN films by plasma enhanced atomic layer deposition and magnetoelectric coupling with nickel for energy harvesting applications
No full text
Lead-Free Ferroelectric Potassium Sodium Niobate Thin Films from Solution: Composition and Structure
No full textA film-texture driven piezoelectricity of AlN thin films grown at low temperatures by plasma-enhanced atomic layer deposition
No full textProbing Antiferroelectric-Ferroelectric Phase Transitions in PbZrO3 Capacitors by Piezoresponse Force Microscopy
No full textpeer reviewe
films [Invited]
No full textpeer reviewedElectro-optic thin film materials, which change their refractive index upon the application of an electric field, are crucial for the fabrication of optical modulators in integrated photonic circuits. Therefore, it is key to develop strategies to tune the linear electro-optic effect. Strain engineering has arisen as a powerful tool to optimize the electro-optic coefficients in ferroelectric thin films. In this report, the electro-optical properties of polycrystalline bismuth ferrite (BiFeO3) thin films are studied. The electro-optic coefficients (reff) of low-cost solution-processed BiFeO3 films under different substrate-induced thermal stress are characterized using a modified Teng-Man technique in transmission geometry. The influence of poling state and substrate stress on the electro-optical properties are discussed. The films show a notable piezo-electro-optic effect: the effective electro-optic coefficient increases both under compressive and tensile in-plane stress, with compressive stress having a much more profound impact. Electro-optic coefficients of 2.2 pm/V are obtained in films under a biaxial compressive stress of 0.54 GPa
