Scanning transmission electron microscope mapping of electronic transport in polycrystalline BaTiO3 ceramic capacitors

We report electronic transport mapping in a single dielectric layer of a polycrystalline BaTiO3 multilayer ceramic capacitor (MLCC) by electron beam induced current (EBIC) measurements using a scanning transmission electron microscope. Ga+ focused ion beam-lift out techniques with organometallic Pt-deposition are used to extract and electrically connect to these devices while maintaining high (>gigaohm) resistance between electrodes. Different modes of EBIC are observed depending on device resistivity. We demonstrate the use of EBIC resulting from secondary electron emission as a method for performing resistance contrast imaging (RCI), with resistive grain boundaries appearing as steps in EBIC contrast. These RCI maps are also used to calculate the potential and electric field of the device under an arbitrary bias. A mix of high- and low-resistance ohmic as well as rectifying grain boundaries is observed. These results help to better establish the distribution of resistivities critical to the prevention of performance-limiting current leakage in MLCCs.