Photoluminescence of 4H-SiC: some remarks

Low temperature photoluminescence (LTPL) measurements have been performed on bulk wafers and epilayer crystals of 4H-SiC. The understanding of a LTPL spectrum is not straightforward, especially for the characterization of films grown on substrates. Some typical examples are presented, such as LTPL spectra from n-type substrates, epilayers with various qualities, and the temperature dependence of the near band gap emission. Both the wavelength of the excitation source and the quality of the layer are shown to influence the interpretation of the LTPL data.