Nonparabolicity effects on cyclotron mass in GaAs quantum wells

Abstract
Cyclotron-resonance measurements are reported on GaAs/(Ga,Al)As quantum wells of various thicknesses between 58 and 373 Å. It is found that the cyclotron mass can be understood in terms of a parallel effective mass which is more enhanced by conduction-band nonparabolicity than the perpendicular mass, relevant for calculating the confinement energies. The measured cyclotron-resonance masses agree well with the theoretical approach of Ekenberg [Phys. Rev. B 40, 7714 (1989)]. This confirms the validity of describing band nonparabolicity in terms of a reliable energy-dependent effective mass that can be used to compute, e.g., shallow donor levels in GaAs-based heterostructures.