A quantum cascade laser and method of making are disclosed. The quantum cascade laser includes a plurality stages configured in a cascade structure, each stage having a quantum well emission layer and an injection layer, each stage having an upper laser level and a lower laser level. A scattering barrier is located in the quantum well emission layer, the scattering barrier being positioned such that interface roughness (IFR) scattering at the lower laser level is greater than IFR scattering at the upper laser level. The scattering barrier may be located to maximize IFR scattering for the lower laser level and/or minimize IFR scattering for the upper laser level.