Multisubband plasmons: Beyond the parabolicity in the semiclassical model

This work studies the impact of the nonparabolicity on the formation of multisubband plasmons. We explore three semiclassical optical response models and compare their predictions to temperature-dependent absorption measurements from three structures: all doped GaAs/AlGaAs quantum wells with continuously varied parabolic binding potentials. We show that qualitative improvement in the prediction of the plasmon absorption peak can only be obtained by including both the energy and wave-function dependence on the in-plane wave vector. Our model, developed to include both these dependencies, uses a k⋅p-derived current density operator (instead of the usual scalar effective mass one). The model should be readily generalizable to a wide set of nanostructures, such as asymmetric half-parabolic wells or narrow band materials nanostructures beyond the quasi-Kohn regime.