A Quantum Cascade (QC) structure(s) for use in Quantum Cascade Lasers (QCLs) that use step quantum well(s) in which the radiative and LO-phonon transitions are both vertical transitions and within the same step well. This approach allows for a high oscillator strength and uses LO-phonon scattering for fast depopulation of the middle state (lower lasing state) for maintaining a population inversion. The step also reduces unwanted injection into the lower lasing state due to spatial separation of the wavefunctions. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope of the claims.