FAR-INFRARED OPTICALLY DETECTED CYCLOTRON-RESONANCE IN GAAS-LAYERS AND LOW-DIMENSIONAL STRUCTURES

Novel far-infrared optically detected cyclotron resonance (FIR-ODCR) t echniques are used to investigate GaAs epilayers and the results are c ompared with conventional cyclotron resonance performed at far-infrare d frequencies and ODCR at microwave frequencies. The FIR-ODCR techniqu e shows remarkable resolution and sensitivity and has been applied to investigations of the electronic structure of low-dimensional systems. In particular, cyclotron resonance has been optically detected in a G aAs/GaAlAs multiple quantum well (MQW) sample and compared with ODCR r esults performed at microwave frequency. Multi-single quantum wells (M SQW) in an MBE GaAs/GaAlAs structure with different well thicknesses h ave also been investigated, and by detecting cyclotron resonance via t he FIR-induced changes in the luminescence of the separate wells, the power of the technique to investigate the cyclotron resonance mass ver sus well thickness in a single sample has been demonstrated. Finally, the experimentally determined values of effective mass for different w ell widths are compared with the theoretical results, showing good agr eement.