An electrode-free method of characterizing the microwave dielectric properties of high-permittivity thin films

作者：Bovtun V^*; Pashkov V; Kempa M; Kamba S; Eremenko A; Molchanov V; Poplavko Y; Yakymenko Y; Lee J H; Schlom D G

来源：Journal of Applied Physics, 2011, 109(2): 024106.

DOI：10.1063/1.3537835

A thin dielectric resonator consisting of a dielectric substrate and the thin film deposited upon it is shown to suffice for microwave characterization and dielectric parameter measurement of high-permittivity thin films without electrodes. The TE(01 delta) resonance mode was excited and measured in thin (down to 0.1 mm) rectangular-or disk-shaped low-loss dielectric substrates (D similar to 10 mm) with permittivity epsilon' >= 10 inserted into a cylindrical shielding cavity or rectangular waveguide. The in-plane dielectric permittivity and losses of alumina, DyScO(3), SmScO(3), and (LaAlO(3))(0.29)(SrAl(1/2)Ta(1/2)O(3))(0.71) (LSAT) substrates were measured from 10 to 18 GHz. The substrate thickness optimal for characterization of the overlying thin film was determined as a function of the substrate permittivity. The high sensitivity and efficiency of the method, i.e., of a thin dielectric resonator to the dielectric parameters of an overlying film, was demonstrated by characterizing ultrathin strained EuTiO(3) films. A 22 nm thick EuTiO(3) film grown on a (100) LSAT substrate and strained in biaxial compression by 0.9% exhibited an increase in microwave permittivity at low temperatures consistent with it being an incipient ferroelectric; no strain-induced ferroelectric phase transition was seen. In contrast, a 100 nm thick EuTiO(3) film grown on a (110) DyScO(3) substrate and strained in biaxial tension by 1% showed two peaks as a function of temperature in microwave permittivity and loss. These peaks correspond to a strain-induced ferroelectric phase transition near 250 K and to domain wall motion.

• 出版日期2011-1-15