Coexistence of excitons and Landau states in In 0.53Ga 0.47As/InP quantum wells at room temperature

Abstract

We have studied the magneto-optical Kerr ellipticity of the electron-heavy-hole states of two lattice-matched InGaAs/InP multi-quantum-wells (MQW) with different barrier widths at room temperature. Using Lorentzian line shapes the analysis of the oscillations in the spectra reveals excitonic states and up to six Landau states. The energy shifts of the excitonic ground state in low and high magnetic fields allow us to estimate the dimensionality of the electronic system. For the higher excited states no excitonic behaviour is observable. At higher magnetic fields clear deviations from the linear Landau-shift occur. Using the nonparabolicity of the conduction band, described by the k· p -theory by Kane, and a constant heavy-hole mass m hh we are able to assign every energy transition to its corresponding Landau level. From the Landau charts we evaluate the energy dependence of the reduced effective mass up to 200 meV above the band gap of InGaAs. The heavy-hole effective mass shows no dependence on energy, but its value is influenced by the strength of the quantum confinement.