Cyclotron resonance in short period (GaAs)(n)/(A1As)(n) superlattices

Cyclotron resonance measurements have been carried out to evaluate the effective mass of electrons in short-period (GaAs)(n)/(AlAs)(n) superlattices (SLs). In order to clarify the Gamma-X crossover occurring at n approximate to 12 due to the zone folding effect, we have measured effective masses in SLs with PL ranging from 8 to 16 using cyclotron resonance in high magnetic fields (up to 150 T). We found a clear cyclotron resonance in the transmission of 10.61 mu m radiation at 99 T in type I SLs (corresponding to an effective mass of 0.098m(0) and broad cyclotron resonances at around 90 T in type II SLs in the transmission of 23 mu m radiation, which give an effective mass of 0.21 +/- 0.01m(0). These resonances were found to be nearly independent of the number of monolayers n.