Cyclotron masses in InGaAs/GaAs superlattices and InGaAs/AlAs superlattices

Cyclotron resonance (CR) measurements have been carried out to evaluate the effective mass of electron in (InGaAs)(n)/(GaAs)(n) superlattices (SLs) an d (InGaAs)(n)/(AlAs)(n) SLs. To clarify the dependence of cyclotron mass on the monolayer number n, we measured CR signals using pulsed high-magnetic fields up to 150 T and a far-infrared laser. We found clear cyclotron reson ances in the transmission of 10.6 mu m at 75 T at room temperature in (InGa As)(n)/(GaAs)(n) SLs and little dependence on the monolayer number n in the SLs. However, for (InGaAs)(n)/(AlAs)(n) SLs, a large dependence of cyclotr on mass on the monolayer number n was observed. We consider that these depe ndencies are related to the difference between the barrier height in the SL s and the influence of nonparabolicity on the conduction subbands in the SL s. (C) 2000 Academic Press.