The use of a sacrificial water-soluble
BaO layer was investigated
for the purpose of fabricating free-standing single-crystalline BaTiO3 membranes for vibrational energy harvesting applications.
An epitaxial BaTiO3/SrTiO3/BaO heterostructure
was deposited on a SrTiO3(001) substrate by pulsed laser
deposition. The sacrificial BaO layer was dissolved by immersing the
heterostructure in water. A single-crystalline BaTiO3 membrane
was thereby released from the SrTiO3(001) substrate and
transferred onto a glass or polyethylene terephthalate (PET) substrate
coated with a polydimethylsiloxane (PDMS) adhesion layer. A 200 nm-thick
BaTiO3 membrane was sandwiched between two flexible PDMS/ITO/PET
electrode layers, forming a vibrational energy harvester test device
that could operate at an average electrical power output of over 1
μW. This membrane fabrication process is applicable to various
flexible structures and materials in vibrational energy harvesting
or dynamic strain-sensing applications.