The three-layer heterostructure formed by the two domains of the cubical 3C-SiC polytype and hexagonal NH-SiC (N = 4, 6, 8) layer is considered. The Poisson equation with the account of spontaneous polarization for the hexagonal component has been solved with the assumption that the resulting electric field can be treated as a sum of contact and polarization field components. The analytical expression for the value of the dimensionless band-bending potentials on the interfaces is found. It is demonstrated that the account of the spontaneous polarization leads to the asymmetry of the energy diagram, which results in an inequality of the quantum wells located at the interfaces. The possibility of the indirect electronic transition between the states of these quantum wells is considered.