Identification of Electrically Stressed Regions in AlGaN/GaN-on-Si Schottky Barrier Diode Using EBIC Technique

The mapping of the current induced by a focused electron beam in a scanning electron microscope (SEM) has been used to localize electrically stressed regions in the AlGaN/GaN-on-Si Schottky barrier diode (SBD) structures cross-sectioned by the focused ion beam (FIB) technique. We have shown that homogeneously distributed electron beam induced current (EBIC) intensity detected below the Schottky contact at 0 V changes with increasing reverse voltage V _R and peaks at the edges of a field-plate region. The build-up of local microavalanches at high electric voltages has been indicated by overexposed EBIC signal at areas following the edges of the field plate structure. Interpretation of EBIC measurements is supported by electro-physical modeling and simulations employing the 2-D finite element method in Synopsys TCAD Sentaurus. The simulations prove that the electric field intensity in the SBD locally reaches values sufficiently high to trigger multiplication of the excessive carriers generated by an electron beam, which helps one to visualize and localize critical regions in GaN-based power electronic devices by the EBIC method.