Investigations of langanite and langatate materials for use in SAW device applications

This paper will present recent results and investigations of langanite (LGN) and langatate (LGT) materials for use in SAW device applications. These substrates offer new possibilities for device applications given their slower phase velocities, higher coupling and high temperature operation without degradation of the piezoelectric properties. This paper will present recent results on the extraction of SAW material parameters and device performance for various cut angles. The SAW parameter extraction approach used for these experiments is summarized. Measured resonator Q of the order of 4000 has been obtained with the currently designed devices on Y-cut, showing promising behavior for these materials and orientations. Delay line data is used to extract the phase velocity, coupling coefficient and transducer capacitance. The work discusses the correlation between measured phase velocity, electromechanical coupling coefficient and IDT capacitance, and the predicted parameter performance. Measured SAW resonator temperature coefficient of delay (TCD) data will be presented and compared to expected values for the selected cut angles and propagation directions. The results reported are obtained from LGN and LGT materials from Crystal Photonics, Inc., (CPI) which provides boules that are typically clear, transparent and free of visible defects.