Sacrificial Water-Soluble BaO Layer for Fabricating Free-Standing Piezoelectric Membranes
Ryota Takahashi, Mikk Lippmaa
Abstract
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.