Optical investigation methods for SiC device development: application to stacking faults diagnostic in active epitaxial layers

We present a review of the different optical techniques that can be used to investigate the presence of as- grown and/ or process- induced stacking faults ( SFs) in 4H - SiC epitaxial layers. A SF is always a finite admixture of different polytypes, and we begin with a brief review of the systematic of SiC polytype structure and electronic properties. Next, we discuss the optical signature and compare with the results of several model calculations, taking successively into account the effect of valence band offset, internal polarization and non- homogeneity of the potential well. Finally, we consider cathodo- luminescence and micro- photoluminescence techniques and show that, in both cases, some screening of the built- in electric field can be achieved.