Focussing on the fine structure of excitons bound to large 2-dimensional stacking faults in a 4H-SiC matrix, we show that the intrinsic type-II nature of the band alignment, combined with the effect of the spontaneous polarization, should result in a double bound-exciton signature per well. Then, we present the first observation of a 3C-QW sandwiched between two higher energy bandgap, polytypes in a 3C-SiC matrix.