  In this paper strain transfer efficiencies from single crystalline
piezoelectric lead magnesium niobate-lead titanate (PMN-PT) substrate to a GaAs
semiconductor membrane bonded on top are investigated using state-of-the-art
x-ray diffraction (XRD) techniques and finite-element-method (FEM) simulations.
Two different bonding techniques are studied, namely gold-thermo-compression
and polymer-based SU8 bonding. Our results show a much higher strain-transfer
for the "soft" SU8 bonding in comparison to the "hard" bonding via
gold-thermo-compression. A comparison between the XRD results and FEM
simulations allows to explain this unexpected result with the presence of
complex interface structures between the different layers.
