Surface acoustic wave characteristics of A1N thin films grown on a polycrystalline 3C-SiC buffer layer

摘要

In this study, AIN thin films were deposited on a polycrystalline (poly) 3C-SiC buffer layer for surface acoustic wave (SAW) applications using a pulsed reactive magnetron sputtering system. AFM, XRD and FT-IR were used to analyze structural properties and the morphology of the AlN/3C-SiC thin film. Suitability of the film in SAW applications was investigated by comparing the SAW characteristics of an interdig-ital transducer (IDT)/AlN/3C-SiC structure with the IDT/AIN/Si structure at 160 MHz in the temperature range 30-150 ℃. These experimental results showed that AIN films on the poly (111) preferred 3C-SiC have dominant c-axis orientation. Furthermore, the film showed improved temperature stability for the SAW device, TCF= -18 ppm/℃. The change in resonance frequency according to temperature was nearly linear. The insertion loss decrease was about 0.033 dB/℃. However, some defects existed in the film, which caused a slight reduction in SAW velocity.