Optical investigation of stacking faults in 4H–SiC epitaxial layers: Comparison of 3C and 8H polytypes

We present an analysis of the electronic structure of in-grown 3C and 8H stacking faults (SFs) in a 4H–SiC matrix. First, the concept of low-temperature photoluminescence optical signature of SFs is discussed. Then, the results of type-II quantum well (QW) model calculations are displayed, taking into account the effect of the valence band offset, internal polarization field and non-homogeneity of the potential well. In this case, we show that a satisfactory description of 3C QWs signature can be reached. The situation is entirely different for 8H. Since a 8H-unit cell is nothing but two 3C lamellae coupled by an hexagonal turn, we investigate in detail the effect of coupling more and more two 3C lamellae until a final 8H QW is found. In this way, we show that a reasonable agreement with experimental data can be reached.