The pressure dependence of the effective mass in a GaAs/AlGaAs heterojunction

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Abstract
Cyclotron resonance at high magnetic field with radiation in the far infrared has been used to measure the pressure coefficient of the effective mass, dm*/dp, of a GaAs heterojunction at pressures up to 8 kbar. Pressure is known to reduce the carrier concentration ns. In this experiment, persistent photoconductivity was used to vary ns for each pressure so that dm*/dp was measured for fixed ns. Furthermore, the energy dependence of the effective mass was determined for each ns and p. The authors find that, within an experimental error of approximately 5%, dm*/dp for the heterojunction is equal to dm*/dp for bulk GaAs, independent of ns. This is understood from a simple k.p model. Anomalously ns-dependent pressure coefficients were observed for some cyclotron energies, which the authors relate to anomalous cyclotron mass values, perturbed from their true values by a number of effects that complicate cyclotron resonance in two dimensions.