Device Characteristics of Radio Frequency SAW Filter Fabricated on GaN Thin Film

SAW Characteristics of undoped GaN thin film such as velocity, electro-mechanical coupling coefficient k$^2$, temperature coefficient of frequency (TCF), and propagation loss were investigated. GaN thin film was deposited on sapphire substrate by MOCVD. SAW velocity of 5352 m/s and TCF of $-$61.8 ppm/$^\circ$C were measured at kh value of 0.3 and a temperature range -30 $\sim$ 80 $^\circ$C. k$^2$ was varied from 4.01 \% to 1.36 \%. The fabricated SAW filter exhibited good device performance with insertion loss of $-$36 dB and side lobe attenuation of 20 dB at the wavelength of 40 $\mu$m ($\lambda$/4 = 10 $\mu$m). The center frequency was 133.8 MHz. KCI Citation Count: 3