Magnetooptical studies of excitons in compound semiconductor systems with polarizability differences

Magnetic and optical (magneto-optical) characters of electron-hole pairs (excitons) in compound semiconductor systems were studied. I-VII to III-V compound semiconductor systems were studied in terms of the polarization differences, which give rise to changes of exciton properties under magnetic fields and/or in quantum confinement effect.;Magnetic Circular Dichroic (MCD) measurements up to 6 Tesra (T) and Photoluminescence Excitation (PLE) spectra up to 25 T were performed to investigate spin splittings around exciton absorption spectral regions.;CuCl thin films as a I-VII with large polarization system showed the exciton confinements in the Long Wave Approximation (LWA) region when those thicknesses were 8 ∼ 29 nano meter (nm). The translational motion of lowest exciton is quantized in LWA region which results in even-numbered quantized states were not observed in the transmission spectra. The g-values of odd-numbered states deduced from the MCD spectra indicated a weak variation on spin splitting of the 3rd-quantized state.;Zn (1-x) Cd (x) Se/ZnSe multi quantum wells (MQW) as a II-VI system showed a dramatic variation of exciton g value, depending on both the well width (Lw) and the Cd composition (x). An exciton g-value of 1.95 was obtained at Lw = 4.5 nm, x = 0.062, respectively. The g-value was 6 times of that of a lowest exciton state in these MQWs. The possibility of intentional control of the exciton g-value in a nonmagnetic II-VI compound system had been successfully presented.;The two dimensional excitons in GaAs/AlAs MQW as a III-V system under high magnetic fields were successfully observed. Up to 25 T, clear excitonic effects revealed on top of the Landau-level structure. The results indicate that Coulomb interaction plays an important role even under high magnetic fields, in contrast to the common belief that it should be only a weak perturbation to the Landau level.;The polarization of materials determines the exciton-Bohr radius and give rise to variations of exciton g-values under magnetic fields. Importantly, the II-VI materials with an intermediate polarization in compound systems, showed dramatic variations of the exciton g-value as a function of the well width and the composition in the MQW.