Photoluminescence spectroscopy on excitonic states of narrow GaAs–AlGaAs single quantum wells in high magnetic field

Magneto-photoluminescence (PL) experiments of very thin GaAs/Al0.3Ga0.7As quantum wells were performed in a magnetic field (B) of up to 20 T. It has been observed that the diamagnetic shift changes abruptly from beta B-2 to alpha B around 5 T as B increases, and both ct and beta become larger as the well-width increases. This B-dependent transition is indicative of the change of electron-hole (e-h) coupling as the cyclotron radius becomes comparable with that of the exciton. The change of PL linewidth by B also supports the concept that the e-h recombination is sensitive to the dimensionality. (C) 1998 Academic Press.