The role of non-abruptness of Ge profile on the effective mass of holes confined in the Si/Si Ge/Si Quantum well

Effective mass of two-dimensional hole gas confined in the Silicon/Silicon Germanium/Silicon quantum well extracted from Shubnikov-de Haas experiments, have been analyzed and their sheet density dependence has been explained in terms of non-parabolicity of heavy hole sub-band, and non-abruptness of Ge profile at the interfaces. The decrease of hole effective mass with enhancing density in the inverted interface can not be justified solely by non-parabolicity effect, indicating that the role of non-abruptness must be accounted too for this behaviour