On the Occasion of Approaching Fifty Years of Type II Superlattices: A Clarifying Comment

The present communication creates a permanent record of an earlier clarification concerning the paper that originated the Type II superlattice field in 1977, “A New Semiconductor Superlattice.” It is emphasized that the theoretical treatment employed a one-dimensional Kronig–Penney framework in which both layers of the superlattice period were semiconductors described within Kane’s two-band model. No additional Bloch functions were introduced. The Bloch basis was fixed; only the material parameters entering the Hamiltonian differed between layers. The approach produced quantitatively accurate results, including the demonstration of infrared band-gap tunability through material composition and structural variation. The Appendix reproduces a representative original FORTRAN program listing from the late 1970s used in calculating Type II superlattice properties.