Optoelectronic devices with 1D modulation of the potential through hetero-structure or doping superlattices have so far been the privilege of III-V semiconductors. Based on the fact that SiC can be grown monolayer by monolayer, and that Si–Si and C–C double layers have been observed in it, we suggest the possibility of a stress-free polarization superlattice, consisting of the periodic variation of Si-face and C-face domains along the hexagonal axis of 4H-SiC. Such a structure could, in principle, be grown by molecular source atomic layer epitaxy. Investigating such superlattices by density functional theory, using a hybrid functional, we show that Si–Si and C–C double layers at the antiphase boundaries confine electrons within ~0.5 nm, and the periodic polarization field causes zig-zag shaped band edges which gives rise to tunable absorption, to spatial separation of free electrons and holes, as well as to optical nonlinearity. These properties could allow the application of SiC also in optoelectronics and photonics.