Elastic strain fields based on single crystal piezoelectric elements represent an effective way for engineering the quantum dot (QD) emission with unrivaled precision and technological relevance. However, pioneering researches in this direction were mainly based on bulk piezoelectric substrates, which prevent the development of chip-scale devices. Here, we present a monolithically integrated Microelectromechanical systems (MEMS) device with great potential for on-chip quantum photonic applications. High-quality epitaxial PMN-PT thin films have been grown on SrTiO3 buffered Si and show excellent piezoelectric responses. Dense arrays of MEMS with small footprints are then fabricated based on these films, forming an on-chip strain tuning platform. After transferring the QD-containing nanomembranes onto these MEMS, the nonclassical emissions (e.g., single photons) from single QDs can be engineered by the strain fields. We envision that the strain tunable QD sources on the individually addressable and monolithically integrated MEMS pave the way toward complex quantum photonic applications on chip.

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Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) compounds, which are typically used for high performance actuator applications due to their outstanding piezoelectric properties, show, in addition, a pronounced electrocaloric (EC) effect. The study of epitaxial films is a useful tool to analyze the correlation between the microstructure and EC properties in order to optimize the performance of these materials. Therefore, the 0.9PMN-0.1PT films were grown by a pulsed laser deposition on (001) as well as (111) oriented SrTiO3 single crystalline substrates using a La0.7Sr0.3CoO3 buffer as the bottom electrode and additional Au top electrodes. The structural properties determined by a high resolution X-ray and electron microscopy techniques indicated an undisturbed epitaxial growth. The anisotropy of the ferroelectric domain structure was investigated by a vertical and lateral piezoresponse force microscopy showing clear differences between the two orientations. A significant reduction of the thermal hysteresis was observed in the T-dependent polarization measurements for (111) oriented PMN-PT films, whereas the indirectly determined EC properties yield a maximum ΔT of around 15 K at 40 °C for a field of about 400 kV/cm for both film orientations