Leaky surface acoustic waves on Ca ₃ TaGa ₃ Si ₂ O ₁₄ /high-velocity substrate-bonded structures

Abstract Leaky surface acoustic waves (LSAWs) on bonded structures of a rotated Y-cut Ca 3 TaGa 3 Si 2 O 14 (CTGS) thin plate and a high-velocity support substrate were investigated theoretically and experimentally. Sapphire, 3C-SiC, quartz, and LiNbO 3 (LN) were included as support substrates in the theoretical calculations. For sapphire substrate, a maximum electromechanical coupling factor K 2 of 2.9% was observed at CTGS cut angle of 90° and a CTGS thin plate thickness of 0.3 wavelengths at which the LSAW attenuation vanishes. For the LN substrate, a zero-temperature coefficient of frequency (TCF) was obtained by adjusting the plate thickness because of the cancellation of the large negative TCF and the positive TCF of the CTGS. LSAW resonators were fabricated on a 0° YX -CTGS/15° YX -LN bonded structure and evaluated at 460 MHz. High Q factors and excellent TCF with −7.6 ppm °C –1 and −16 ppm °C –1 for resonance and antiresonance frequencies, respectively, were experimentally demonstrated.