Determination of doping levels and their distribution in SiC by optical techniques

We review an absorption measurement based characterization method for the determination of doping levels and doping level distribution in SiC which is quantitative and serves all the advantages of optical techniques like being non-contact, non-destructive and quick. Calibration plots for the important SiC polytypes 4H-SiC and 6H-SiC, both n- and p-type, have been determined in the technological relevant charge carrier concentration range of 1017–1019 cm−3. The underlying physical phenomena of the measurement technique as well as the experimental setup and its precision will be discussed. Several absorption mappings will be shown in order to demonstrate the potential of the presented method as research as well as industrial quality testing tool of SiC wafers. In an outlook the application of the method for other semiconductor materials like GaAs will be discussed.