Photoluminescence intensity oscillations with magnetic field in InGaAs quantum wells*

We have observed magnetic field oscillations in the photoluminescence (PL) intensity from InGaAs quantum wells (QWs) with indium compositions of 5{\%} and 15{\%} with laser excitation close to the bandgap for temperatures $<$ 20 K. For all samples the intensity maxima occur at 2.2 and 4.5 tesla when the magnetic field is applied perpendicular to the QW plane. Experiments in which the sample normal (z-axis) is tilted with respect to the applied magnetic field $B$ show that the PL intensity maxima positions depend on the magnetic field component $B_{z}$. Time-resolved PL comparison with GaAs QWs yields much longer recombination times for the InGaAs QWs. Furthermore, cross sectional scanning tunneling microscopy studies indicate the formation of Indium rich InGaAs clusters in the InGaAs QWs. We interpret the observed oscillations in terms of the Aharonov-Bohm effect and quasi-indirect excitons with ring-like trajectories of carriers. The oscillation period corresponds to orbits with radius equal to 24 nm.