Cyclotron resonance of high-mobility (up to 300000 cm2 V-' s-' at 100 mK) GaAsIAiGaAs two-dimensional hole gases (ZDHGS) grown on (311)A oriented substrates has been measured in magnetic fields up to 17 T and at temperatures down to 350 mK. The ZD hole density is in the range (1.C-2.0) x 10" cm-'. Two resonances are in general observed: at low magnetic fields the lower-field resonance dominates but a progressive transfer of oscillator strength takes place as the field increases. A self-consistent calculation of the Landau fan diagram for the higher-symmetry (100) direction is used to interpret the data and identify the observed transitions. The key differences between two-dimensional hole gases fqnuco\-A

Cyclotron resonance measurements are reported for both electrons and holes in type II InAs/GaSb superlattices and double heterostructures (OHETS). Superlattice (multi quantum well) samples of InAs/GaSb grown by MOVPE have sufficiently high hole gas mobilities and densities to allow t h e first measurements of hole cyclotron resonance in this system. The measured hole masses are -0.lm. and 0.2 m. . indicating a large reduction over the bulk values d u e lo the decoupling of the valence band by strain and confinement. This is ingood agreement with eight-band k . p theory reported here, and previous calculations. The electron masses in both superlattices and OHETS are found to be strongly influenced by non-parabolicity and the carrier concentration. leading lo considerable increases over the band edge values. Similar values are found for both electron and hole masses in structures grown along both [OOI] and [111JA directions

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The cyclotron resonance of high-mobility GaAs/Al x Ga 1Ϫx As heterojunctions displays both a temperature and Landau-level occupancy dependence. For occupancies below ϳ1/10, the behavior is identical to that found in high-purity bulk GaAs with spin splitting of the resonance. The position of the two peaks changes only slightly as the temperature is raised from 0.1 to 2 K. For 1 10 рр 1 6 , the peak position and relative peak intensity of the two peaks shifts radically as the temperature is raised or the density varied. At integral and greater occupancies only a single cyclotron resonance peak is observed whose position changes very little with temperature. Finally, the fractional regime with occupancies between 1 6 and 1 shows only a single cyclotron resonance with a slight temperature dependence and provides no evidence that the many-body interactions responsible for the fractional quantum Hall effect influence the cyclotron resonance. The experimental cyclotron resonance behavior can be explained by a recently published theory by Cooper and Chalker which models the system in terms of the Coulomb interaction and the thermal population of both spin states. A rigorous comparison between data taken over a wide range of densities and temperatures and the theoretical model establishes the validity of this explanation. ͓S0163-1829͑96͒03843-X͔