Optical absorption by excitons in semiconductor quantum wells in tilted magnetic and electric fields

摘要

An analytical approach to the problem of the fundamental and exciton magnetoelectroabsorption in a narrow quantum well (QW) is developed. The external magnetic and electric fields are parallel and both tilted with respect to the QW growth axis. The width of the QW is taken to be much less than the magnetic length and the exciton Bohr radius. The effect of the electric field on size quantized states reduces to the size-quantized Stark shift of the well subbands. Analytical dependencies of the coefficient of the optical absorption and the exciton binding energy on the strengths of the external fields, width of the QW, exciton parameters and tilt angle are obtained and discussed. Novel effects forbidden in bulk material are found to occur. These are based on the interplay between the parallel magnetic and electric fields which in turn is caused by the splitting of the tilted fields into transverse and longitudinal components. In particular, an inversion effect is revealed. Estimates of the expected experimental values are provided for GaAs/AlGaAs QW.