In operando imaging of the space-charge region in a 4H-SiC MOSCAP using STEM-EBIC

In situ biasing electron microscopy is the necessary step forward in being able to characterise nanoscale devices and device interfaces. STEM-EBIC is a new approach that can help fill the missing gaps in creating reproducible methodologies for in situ biasing TEM. The ability to visualise electric fields in in operando lamella scale devices makes it possible to move past the previous approach of dissecting devices post failure. For STEM-EBIC to be useful for in operando device characterisation it is necessary to understand the effects of electron beam interactions with the sample and the behaviour of the device under a variable bias. This paper shows how sample charging is controlled by the scan direction and how this affects the interpretation of STEM-EBIC experiments. This work also maps the local changes in electric field in a metal/oxide/semiconductor 4H-SiC capacitor as it changes between the accumulation and depletion regimes.