Microwave dielectric properties of BNT-BT0.08 thin films prepared by sol-gel technique

作者：Huitema L; Cernea M; Crunteanu A; Trupina L; Nedelcu L; Banciu M G; Ghalem A; Rammal M; Madrangeas V; Passerieux D; Dutheil P; Dumas Bouchiat F; Marchet P; Champeaux C

来源：Journal of Applied Physics, 2016, 119(14): 144103.

DOI：10.1063/1.4945822

We report for the first time the microwave characterization of 0.92(Bi0.5Na0.5)TiO(3-)0.08BaTiO(3) (BNT-BT0.08) ferroelectric thin films fabricated by the sol-gel method and integrated in both planar and out-of-plane tunable capacitors for agile high-frequency applications and particularly on the WiFi frequency band from 2.4 GHz to 2.49 GHz. The permittivity and loss tangent of the realized BNT-BT0.08 layers have been first measured by a resonant cavity method working at 12.5 GHz. Then, we integrated the ferroelectric material in planar inter-digitated capacitors (IDC) and in out-of-plane metal-insulator-metal (MIM) devices and investigated their specific properties (dielectric tunability and losses) on the whole 100 MHz-15 GHz frequency domain. The 3D finite-elements electromagnetic simulations of the IDC capacitances are fitting very well with their measured responses and confirm the dielectric properties determined with the cavity method. While IDCs are not exhibiting an optimal tunability, the MIM capacitor devices with optimized Ir/MgO(100) bottom electrodes demonstrate a high dielectric tunability, of 30% at 2.45 GHz under applied voltages as low as 10 V, and it is reaching 50% under 20V voltage bias at the same frequency. These high-frequency properties of the MIM devices integrating the BNT-BT0.08 films, combining a high tunability under low applied voltages indicate a wide integration potential for tunable devices in the microwave domain and particularly at 2.45 GHz, corresponding to the widely used industrial, scientific, and medical frequency band.

• 出版日期2016-4-14