Experimental and theoretical investigations of some useful langasite cuts for high-temperature SAW applications

Jochen Bardong (1) , Thierry Aubert (2) , Natalya Naumenko (3) , Gudrun Bruckner (1) , Sabine Salzmann (1) , Leohnard M. Reindl (4)

1 CTR - Carinthian Tech Research
2 SYMME - Laboratoire SYstèmes et Matériaux pour la MEcatronique
3 Moscow steel and alloys Institute, Russia
4 IMTEK - Department of Microsystems Engineering [Freiburg]

Passive high-temperature sensors are a most promising area of use for SAW devices. Langasite (La3Ga5SiO14; LGS) has been identified as promising piezoelectric material to meet high-temperature SAW challenges. Because it is necessary to know the material behavior for an accurate device design, the frequency-temperature behavior of Rayleigh SAW (R-SAW) and shear-horizontal SAW (SH-SAW) LGS cuts is investigated on delay line and resonator test structures up to 700°C by RF characterization. In the range of the 434-MHz ISM band, the (0°,22°,90°) SH-SAW cut shows thermal behavior similar to the (0°,138.5°,26.7°) R-SAW cut. Associated with the (0°,22°,31°) cut, in which SAWs present mixed types of polarization, the (0°,22°,90°) SH-SAW orientation might allow differential measurements on a single substrate. In the temperature range of 400 to 500°C, delay line test devices using the SH-SAW cut show a considerable drop of signal. Theoretical analysis indicates that this newly described behavior might be a result of anisotropy effects in this cut, occurring in case of any slight misorientation of electrode alignment.

Domaines: Physique [physics]

Jochen Bardong, Thierry Aubert, Natalya Naumenko, Gudrun Bruckner, Sabine Salzmann, et al.. Experimental and theoretical investigations of some useful langasite cuts for high-temperature SAW applications. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2013, 60 (4), pp.814-823. ⟨10.1109/TUFFc.2013.2630⟩. ⟨hal-00923010⟩