Integrating single-crystal LiNbO3 thin film on diamond for high-frequency surface acoustic wave devices

The continuous performance leap of surface acoustic wave (SAW) devices is primarily driven by the evolution of piezoelectric-on-insulator substrates. Featuring exceptional acoustic velocity and thermal conductivity, diamond has emerged as a highly promising successor to existing Si and SiC supporting substrates. In this Letter, we successfully fabricate single-crystal LiNbO3-on-diamond (LNOD) substrates via micro-transfer printing (MTP). This approach circumvents the thermal expansion coefficient mismatch inherent to ion slicing and ensures the superior single-crystallinity that is unattainable via heteroepitaxial growth. The LNOD substrates exhibit an intimate heterointerface, a smooth surface, and excellent crystallinity of thin-film LiNbO3 with a rocking curve full-width at half-maximum of 0.037°. Furthermore, shear horizontal mode SAW resonators operating at 5 GHz on LNOD substrates are demonstrated, marking the first reported responses of SAW resonators on this platform. These results significantly outperform prior works, validating the MTP-fabricated LNOD substrates as promising candidates for future high-performance radio frequency acoustic devices.