Combined exciton-electron transitions in a quantum well with low-dense two-dimensional electron gas

A combined exciton-cyclotron resonance line is found in photoluminescence excitation and reflectivity spectra of semiconductor quantum wells with electron gas of low density, This line appears in a magnetic field due to the combine transition when an incident photon creates an exciton in the ground state and simultaneously excites an electron between Landau levels. An inelastic process of exciton-electron scattering is found in quantum wells under external magnetic fields. The process is spin-dependent and is determined by the exchange interaction of excitons with free electrons. A theoretical model is developed to describe these effects.