Space charge probing in dielectrics at nanometer scale by techniques derived from atomic force microscopy

Charges accumulation and injection in dielectric material remains critical because it is related to a lot of applications or issues. A deep understanding of interfaces phenomena is needed, but classical space charges techniques exhibit less resolution than the required one. Atomic Force Microscopy (AFM) because of its sensitivity to electrostatic force and its high resolution (close to nanometer) appears to be the best method to characterize charges at nanoscale. Here, two techniques are investigated and compare: Kelvin Force Microscopy (KFM) and Electrostatic Force Distance Curve (EFDC). KFM is used to measured surface potential modification induced by charges. However vertical localization of charges seems difficult to attempt. EFDC follows electrostatic force as function of tip-surface distance. This technique appears promising because of its high resolution, sensitivity to charges localization and distance dependance.