“…6 (a) Moreover, the dielectric constant of the AlN-1.0 remains relatively stable with the increase of frequency, while the AlN-0 exhibits sharp decline. Some researches showed that large grain sizes, low surface roughness, compact and uniform structures are associated with large dielectric constants [30][31][32]. Other researches indicated that the dielectric constant is dependent strongly on the orientation [33][34][35] and for AlN films, the dielectric constant along the c-axis is larger than that in the M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 11 basal plane [36], therefore, the films with highly preferred orientation along the c-axis have larger dielectric constants than those with random orientations.…”