Selective Oxidation during AFM Electrical Characterization of Doped SiC Layers

Abstract

The possibility of anodic oxidation of SiC surfaces by a strong, local electric field applied during Atomic Force Microscopy (AFM) under ambient conditions is an interesting method to achieve nanopatterning of SiC, but is also a side-effect to be well characterized and controlled during this kind of AFM measurements if used to determine the local electric properties. In this contribution, we will analyze the local electric fields by finite element simulations in order to quantify the effect of the presence of a water meniscus and of an oxide layer on the SiC surface. Furthermore, we will experimentally highlight the strong influence of the local doping on the anodization, leading to the formation of thicker oxide layers at the location of highly doped SiC. Therefore, the location of these areas can be determined by a simple AFM topography scan after the application of a high field, allowing to detect highly doped SiC areas in complex structures as for example SiC MOSFETs.