On quantum confinement without barriers

Usually in semiconductor heterostructures, such as quantum wells, the quantum confinement is realized by means of heterobarriers, which are simply the band offsets in adjacent materials. Here the arguments are provided, that the energy dispersions in materials (in simple case determined by effective masses) are important as well. Using a simple model system, such as quantum well with an additional heterojunction, it is shown the predominant localization of the carrier density in the regions with higher effective mass. The possibility of different spatial localization of wave function for different subbands is predicted. This can be applied in semiconductor structures such as quantum cascade lasers.