Solid State Technology and Devices Seminar: Engineering of LiNbO3 films for next generation acoustic and energy harvesting applications
Seminar | March 1 | 1-2 p.m. | 521 Cory Hall
Ausrine Bartasyte, FEMTO-ST Institute, University of Franche-Comté, France
The next generation of high frequency wide-band RF filters or frequency-agile filters are urgently needed for the development of 5G infrastructures/networks/communications. Today, LiNbO3 and LiTaO3 single crystals are key materials in electro-optics and RF acoustic filters. This motivates further development of acoustic wave devices based on highly electromechanically coupled LiNbO3 thin films, adapted to the high-frequency applications. The challenges and the achievements in the epitaxial growth of LiNbO3 films and their integration with Si technology and to acoustic devices will be discussed in detail. The deposition techniques enabling the control of film composition/nonstoichiometry of volatile alkali metal oxides & the methods of compositional analysis will be presented. A particular effort was done to achieve the epitaxial growth of films with single controlled orientation and nearly stoichiometric Li2O composition. We have demonstrated an extremely high acoustical performance compatible with filter applications for SAW devices, based on epitaxial LiNbO3 films, operating in the frequency range around 5 GHz. Future prospects of potential applications and the expected performances of thin film acoustic devices are overviewed, as well. Moreover, it was demonstrated that the power density of 9.62 mW .cm-3 (comparable to present performance of lead-based piezoelectric harvester) can be harvested by vibrational energy transducer based on thick LiNbO3 films. Thus, LiNbO3 films might be a lead-free alternative for PZT in vibrational energy harvesters, as well.