Ultra-High tunability of Ba(2/3)Sr(1/3)TiO3-based Capacitors under Low Electric Fields
Résumé
We report the high-frequency electrical characterization of Ba2/3Sr1/3TiO3 (BST) thin films exhibiting a very high dielectric tunability with low losses at 2.45GHz under very low applied electrical fields. BST layers were integrated in out-of-plane Metal-Insulator-Metal (MIM) devices with optimized Ir/MgO(100) bottom electrodes. The high frequency properties of BST films with thicknesses of 200nm, 450nm and 1450nm were thoroughly investigated in the 100MHz - 10GHz domain and exhibit extremely high capacitance tuning abilities of 82%, 81% and 70% respectively, under applied voltages as low as 10V. MIM devices responses show the onset of acoustic resonances associated with the BST electrostrictive behavior under an electric field. By combining high tunability with low resistive losses under low applied voltages, these devices are opening promising avenues for their integration in high-performance tunable devices in the microwave domain and particularly at 2.45GHz, corresponding to the widely used ISM (industrial, scientific and medical) frequency band.