Comparison of non-contacting lifetime measurements on 4H-SiC epiwafers

What is it about?

We compared non-contacting carrier lifetime measurements (time-resolved photoluminescence and microwave-detected photoconductivity decay) on 4H-SiC epilayers on 4H-SiC substrate. We found, that the microwave-detected photoconductivity is sensitive solely to the epilayer, whereas the photoluminescence decay is strongly affected by substrate contributions for thinner epilayers.

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Why is it important?

We expect the importance of carrier lifetime characterization of 4H-SiC epilayers to rise with the latest improvements in structural quality of the layers. In this paper, we show that the employed microwave-detected photoconductivity decay method and the corresponding, commercially available tool, is advantageous for this even for rather thin epilayers. We expect this tool to be helpful in industrial and pre-industrial wafer level characterization of 4H-SiC epilayers for device fabrication.