Temperature Compensation with AlN Film on Y-128° LiNbO3

Y-128° LiNbO3 is a well-known high-electromechanical-coupling Surface Acoustic Wave (SAW) material, but its usefulness is limited because of its poor temperature-stablility property. AlN films have some excellent characteristics, such as high SAW velocity, stable chemical properties, and high-temperature stability. In this research, the c-axis-oriented AlN films were successfully prepared on Y-128° LiNbO3 by the sputtering method and a SAW delay line oscillator under various temperatures was used to measure the temperature coefficient of frequency (TCF) value of this structure. For Y-128° LiNbO3 with an AlN layer, the TCF value was from -76.32 (ppm/°C) to -39.04 (ppm/°C) and the improved quantity was 48.8%. The oscillator frequency at 25°C also increased from 40.0909 MHz up to 41.6221 MHz. It exhibited Y-128° LiNbO3 with an AlN layer that will effectively improve the poor temperature stability and enhance the SAW velocity.