Quantification of Secondary Electron Doping Contrast in the Scanning Electron Microscope on 4H-SiC

Abstract

We discuss the quantification of the secondary electron doping contrast in the scanning electron microscope on 4H-SiC. It has been observed and studied at length mostly on silicon, but no conclusive theoretical model has been proposed yet. Therefore, we propose a simple physical model that allows for a quantification of the doping contrast. It is based on the changes in effective ionization energy for different doping concentrations and types. For a better agreement between our model and the experiment, a locally increased temperature of the electron system or separate quasi Fermi levels for electrons and holes have to be assumed. A line profile of the sample under investigation is compared with a SRIM simulation of the corresponding implant and shows very good agreement.