Highly epitaxial ferroelectric thin films with optimized dielectric properties

Improving the dielectric properties of the highly epitaxial ferroelectric thin films for high frequency tunable microwave elements has been a global target in the past several years. Recently, we have developed a unique technique to achieve the giant dielectric tunability of 80% with extremely low dielectric insertion loss of 0.001 at 1.0 MHz and 0.005 at 12 GHZ from the additional Mn doping (Ba,Sr)TiO3 thin films on (001) MgO. The high frequency (10-30 GHz) dielectric measurements also demonstrate that the Mn:BSTO films are excellent in both dielectric property and very low insertion loss values of only 0.2 dB at 10 GHz and more than 1.5 dB at 30 GHz. On the other hand, we also systematically investigated the highly epitaxial (Pb,Sr)TiO3 and Ba(Ti,Zr)O3 thin films on (001) MgO. The high frequency dielectric property measurements on the as-grown thin films exhibit excellent dielectric properties such as large tunability, low dielectric loss, and good stability. These results indicate that highly epitaxial ferroelectric thin films are good candidates for developing the high-frequency, room-temperature tunable microwave devices.