MnO2 Thin Film Electrodes for Enhanced Reliability of Thin Glass Capacitors

Many dielectric thin films for energy storage capacitors fail by thermal breakdown events under high-field drive conditions. The lifetime of the device can be improved under conditions where the current path within the defect regions in dielectrics is eliminated. Self- healing electrodes were developed by depositing a manganese dioxide ( MnO2) thin film between the glass substrate and an aluminum film. For this purpose, thin films of MnO2 on boroaluminosilicate glass were fabricated via chemical solution deposition and heat- treated at temperatures in the range 500 degrees C- 900 degrees C. The alpha- MnO2 structure was stabilized by Ba 2+ insertion to form the hollandite structure. The phase transition temperature of alpha- MnO2 to Mn2O3 is strongly dependent on the Ba concentration, with transition temperatures of 600 degrees C and 675 degrees C with Ba concentrations of [ Ba]/[ Mn] = 0.04 and 0.1, respectively. The electrical resistivity increased from 4.5 Omega . cm for MnO2 to 10 5 O . cm for Mn2O3. Both dielectric breakdown strength and the associated cleared aluminum electrode area increased with an MnO2 interlayer between Al electrodes and the borosilicate glass. The enhancement in dielectric strength was related with self-healing. The associated redox reaction between MnO2 and Mn2O3 was also proved by RAMAN spectroscopy following dielectric breakdown.