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The electron effective masses, scattering time and mobilities near the Fermi level for the lowest two subbands of the two-dimensional electron gases in a pseudomorphic In0.80Ga0.20As/In0.53Ga0.47As/In0.52Al0.48AsHEMT structure are determined by fitting the cyclotron resonance spectra. The significant enhancement of the electron effective masses, resulting from the conduction band nonparabolicity and the wave function penetration, is observed. The evident subband dependencies of the electron scattering time and mobilities dominated by the alloy scattering and ionized impurities scattering are also discussed.

The resonant subband-Landau-level coupling(RSLC) between the N=1 Landau level of the lowest subband and the N＝0 Landau level of the subbands with quantum index up to i＝5 of two-dimensional electron gases in GaAs/AlGaAs heterojunction was observed under relatively low magnetic field.Several intersubband energies were accurately determined. The experimental results were in good agreement with the self-consistent calculations including the depolarization shift and exciton-like effect corrections.The quantum index dependence of the level splitting due to the RSLC was discussed.

Photoconductivity (PC) spectra of impurities in n type GaAs under magnetic field are presented. The resonant interaction between high excited states of bound electrons and LO phonons under relatively low magnetic field was observed. The magnetic field dependency of PC response of resonant polaron and the physical origin of the PC peak stuck on the energy position of LO phonon are discussed.

The luminescence lines of the neutral donor bound exciton (D 0 X) are investigated in magnetic fields up to 10 T. From the observed Zeeman-splitting and shifting, we deduce to our knowledge for the first time the values of the g -factors and the diamagnetic shifts of the electrons and the hole in this complex.