Electrical properties of BaTiO3 based ferroelectric capacitors grown on oxide sacrificial layers for micro-cantilevers applications

Abstract

An investigation of all oxide ferroelectric capacitors based on SrRuO3/BaTiO3/SrRuO3 multi-layers grown on sacrificial oxide layers of YBa2Cu3O7 and MgO for Micro-Electro-Mechanical systems applications is reported. By insertion of additional MgO or SrTiO3 buffer layers the orientation of the BaTiO3 film can be controlled allowing the fabrication of suspended cantilevers using the 31 and the 33 piezoelectric modes. The electrical properties of SrRuO3/BaTiO3/SrRuO3 capacitors are changed compared with those grown directly on a single crystal substrate by the introduction of sacrificial layers. Circuit modeling of the electrical characteristics of these devices shows that a reduction of the deposition pressure for BaTiO3 produces a decrease of the parasitic shunting conductance (modeled with a resistor in parallel to the capacitance of the device) which reduces the resistive losses present in the BaTiO3 film. However for extremely low deposition pressure the quality of the polarization hysteresis loops is compromised.Particulates present on the surface of the YBa2Cu3O7 increase the parasitic conductance at low frequency in the capacitive structure grown on this sacrificial layer. Good electrical properties are obtained for the capacitive structures grown on top of the MgO sacrificial layers at pressures equal or lower than 8Pa.