Figure1 : Photostriction project
Figure2 : thin film growth - XRD
Figure3 : thin film growth - AFM
Figure4 : electrical characterization
Figure5 : pump-probe measurement
Figure6 : funding OxyMORE
Figure7 : Argonne collaboration
Figure8 : UCSD collaboration
Complex ferroelectric oxides exhibit several functionalities (such as high piezoelectric coefficients and switchable polarization) which can be coupled and exploited in various types of devices (such as microactuators, sensors, energy harvesting structures or high-density memories). While electric fields are mostly applied to manipulate devices functionalities, using light could constitute an alternative and wireless approach with limited power consumption and noise in many potential applications. The generation of strain by light illumination is called photostriction. Up to now, previous works have been mainly focused on ferroelectric ceramics and single crystals but their too long response time prevents their integration in real devices. However, ultrafast photostriction effects are expected in ferroelectrics grown in thin films (thickness~10-100 nm).
The general purpose is to investigate carefully the mechanisms of photostriction which remain not fully understood (including magnitude and time-scale) in ferroelectric thin films integrated in real capacitor geometries, to develop ultrafast light control of strain in functional devices. More precisely, this project aims at clarifying the physical mechanisms behind photostriction in PbZrTiO3 (PZT) thin films, by studying contributions from polarization state and interfaces, in order to optimize the photo-induced strain in devices geometries and develop photostrictive cantilevers. In particular, our work is focused on the effects of thin films chemical composition, thickness and interfaces with electrodes on the devices properties.