Charge injection and decay of nanoscale dielectric films resolved via dynamic scanning probe microscopy

To satisfy continual demands for higher performance dielectrics in multi-layer ceramic capacitors and related microelectronic devices, novel characterization methods are necessary for mapping materials properties down to the nanoscale, where enabling materials developments are increasingly relevant. Accordingly, an atomic force microscopy-based approach is implemented for characterizing insulator performance based on the mapping of discharging dynamics. Following surface charging by biasing a conducting tip contacting a dielectric surface, consecutive non-contact Kelvin force surface potential mapping (KPFM) reveals charge dissipation via exponential decay. In barium titanate (BTO) thin films engineered with distinct microstructures but identical thicknesses, discharging rates vary by up to a factor of 2, with smaller grain size correlating to longer dissipation times, providing insight into optimal microstructures for improved capacitor performance. High-resolution potential mapping as a function of time thereby provides a route for directly investigating charge injection and discharging mechanisms in dielectrics, which are increasingly engineered down to the nanoscale and have global implications given the trillions of such devices manufactured each year.

Automated summary

By using atomic force microscopy to characterize discharging dynamics, researchers have found that microstructures in insulating materials can significantly affect discharging rates. This provides insight into optimizing microstructures for improved capacitor performance.