Applicability of LiNbO3, langasite and GaPO4 in high temperature SAW sensors operating at radio frequencies

René Fachberger; Gudrun Bruckner; Gernot Knoll; Robert Hauser; Jörg Biniasch; Leonhard Reindl

doi:10.1109/tuffc.2004.1367482

Applicability of LiNbO3, langasite and GaPO4 in high temperature SAW sensors operating at radio frequencies

IEEE Trans Ultrason Ferroelectr Freq Control. 2004 Nov;51(11):1427-31. doi: 10.1109/tuffc.2004.1367482.

Authors

René Fachberger¹, Gudrun Bruckner, Gernot Knoll, Robert Hauser, Jörg Biniasch, Leonhard Reindl

Affiliation

¹ Carinthian Tech Research, Europastrasse 4/1, A-9524 Villach, Austria. rene.fachberger@ctr.at

PMID: 15600086
DOI: 10.1109/tuffc.2004.1367482

Abstract

The applicability of LiNbO3, langasite and GaPO4 for use as crystal substrates in high temperature surface acoustic wave (SAW) sensors operating at radio frequencies was investigated. Material properties were determined by the use of SAW test devices processed with conventional lithography. On GaPO4, predominantly surface defects limit the accessible frequencies to values of 1 GHz. Langasite SAW devices could be operated up to 3 GHz; however, high acoustic losses of 20 dB/micros were observed. On LiNbO3, the acoustic losses measured up to 3.5 GHz are one order of magnitude less. Hence, SAW sensors capable of wireless interrogation were designed and processed on YZ-cut LiNbO3. The devices could be successfully operated in the industrial-scientific-medical (ISM) band from 2.40 to 2.4835 GHz up to 400 degrees C.