上海科技大学知识管理系统

This work presents a low temperature coefficient of frequency (TCF) and high-performance S4 mode acoustic resonator based on $128^{\circ} \text{Y}$ LiNbO3/SiO2/a-Si/Si (trap-rich layer assisted LiNbO3-on-insulator, TR-LNOI) substrate. The electromechanical coupling, quality factor, and TCF are optimized for S4 mode by adjusting the thickness ratio of stack layers and the geometry design of the inter-digital transducer. The optimized resonators exhibit a TCF of resonant frequency as low as 0.24 ppm/K, an electromechanical coupling ( ${k}^{{2}}$ ) of 14.8%, a maximum quality factor ( ${Q}_{\text {max}}$ ) of 1406 at 7.43 GHz, resulting a ${k}^{{2}}\cdot {Q}_{\text {max}}$ of 208. This work greatly extends the limit of ${f}_{s}\cdot {k}^{{2}}\cdot {Q}_{\text {max}}$ for suspended thin-film resonators to ${7.43}\times {208}={1545}$ with a near-zero TCF of resonant frequency.