Investigation of characteristics of SAW filter using undoped GaN epitaxial layer grown by MOCVD on sapphire substrate

Characteristics of a SAW filter using GaN thin film such as SAW velocity, electro-mechanical coupling coefficient k², temperature coefficient of frequency (TCF), and propagation loss were investigated. GaN thin film was deposited on sapphire substrate by MOCVD and its characteristics were measured experimentally with changing the kh value from 0.18 to 1.25. Phase velocity was estimated as 5546 m/s, electro-mechanical coupling coefficient k² was ranged from 4.738% to 0.1864%, and TCF was -61.82 ppm/°C. Propagation loss, estimated by measuring insertion loss, was ranged from 3.21×10^-3 dB/λ to 9.10×10^-3 dB/λ with changing kh value