FREE-CARRIER ABSORPTION AND LIFETIME MAPPING IN 4H SIC EPILAYERS

Results of carrier lifetime studies in low-doped epitaxial 4H SiC laye rs are reported. The free carrier absorption (HCA) technique was appli ed to extract. carrier lifetime parameters and their spatial distribut ion in a wide photoexcitation range. The FCA magnitude is shown to sca le linearly with the photoinjected carrier concentration while the abs orption cross section increases according to a lambda(4.4) law for nea r infrared wavelengths. High spatial resolution carrier lifetime mappi ng of large 4H SiC areas revealed features related to structural imper fections of epilayers, Finally, a density dependent fast lifetime comp onent was observed at high injection levels and attributed to band-to- band Auger recombination. (C) 1997 American Institute of Physics.