Magneto-Optics in GaAs-GaAlAs Quantum Wells

Abstract

The inter-band photoconductivity of GaAs-(Ga,Al) As quantum wells has been studied in steady magnetic fields up to 16T. Landau level transitions with indices up to 14 are visible, at energies up to 400 meV above the energy gap of GaAs. The Landau levels persist down to ∼ 2T, enabling an accurate extrapolation to B = O to yield exciton binding energies, which are substantially lower than those deduced from previous high-field measurements. Several diamagnetically-shifted subband excitons are observed, including one associated with a bound state in the spin-orbit-split-off band. The Landau levels are fitted using a calculation of the binding energy of 2D excitons as a function of B /1/: the resulting electron effective masses are checked against pump and probe cyclotron resonance mesurements.