Diamagnetic shift and localization of excitons in disordered quantum wells

Calculations of exciton absorption spectra and wave functions in quantum wells with alloy and interface disorder under the influence of a perpendicular magnetic field are presented. The four-coordinate Schrödinger equation is solved in electron-hole in-plane coordinates thus going beyond the standard factorization ansatz. It is shown that the diamagnetic shift varies remarkably among different states and is not monotonic in energy, which is in agreement with recent experiments. The stronger the localization of the wave function the smaller the diamagnetic shift. Therefore, the diamagnetic shift analysis gives additional information about the local potential landscape in quantum wells.