掺钪氮化铝（ScAlN）薄膜层状结构SAW器件兼具较高的声速V和较大的机电耦合系数K2，具有能够工作于3GHz以上的超高频频段的巨大潜力，有望满足未来移动通信的高频、宽带化发展需求。然而，ScAlN薄膜仅在单晶金刚石、6H-SiC等高速基底上才具有优异的SAW特性，器件的品质因数Q也亟待提高。基于此，本项目拟研究一种基于ScAlN薄膜的新型多层复合SAW器件结构，该结构借鉴IHP-SAW技术，在ScAlN压电薄膜的底部交替沉积了高声速层和低声速层。通过理论分析ScAlN层状结构中SAW传播特性及损耗机理，以指导SAW模式选择、ScAlN薄膜的厚度和掺杂浓度、形成IHP-SAW的高低声速层以及横向导波结构的优化。通过本项目的实施，获得综合性能优异的SAW基片，揭示传播损耗的物理机制，并设计出能够工作在超高频频段的高K2、高Q值且TCF优良的SAW谐振器，为高频宽带SAW滤波器的发展奠定基础。

Scandium-doped aluminum nitride (ScAlN) thin film based layer structures offer high velocity and large electromechanical coupling coefficient simultaneously, and thus have great potential to operate in the ultra-high frequency band above 3GHz. Those excellent performances make it have a very bright prospect to meet the need of high frequency and wide-band for future mobile communication applications. However, the excellent SAW characteristics is only obtainable when ScAlN thin film combined with fast substrate such as diamond and 6H-SiC, and the quality factor Q of the device also urgent needs to be improved. Therefore, inspired by IHP-SAW technology, a new ScAlN thin film-based composite multilayer structure with high velocity and low velocity alternately attached to ScAlN is proposed. Firstly, theoretical analysis of the SAW characteristics and loss mechanism for the multiple SAW modes is performed on the proposed ScAlN-based layere structure, so that provides guidance for selection of SAW mode, optimizing the design of high and low impedance alternating layers, ScAlN thin film thickness and Sc concentration as well as transverse guided wave structure. By the implementation of this project, the ScAlN-based layer structure with excellent SAW performance is obtainable, and the loss mechanism of SAW propagating is revealed. Furthermore, a SAW resonator operating in ultra-high frequency range with large K2 , high Q and excellent TCF is designed, which lays a foundation for the research of high frequency and wide-band SAW filter for application to communication system.