Effect of an in-plane magnetic field on the photoluminescence spectrum of modulation-doped quantum wells and heterojunctions
01 January 2005
The photoluminescence (PL) spectrum of modulation-doped GaAs/AlGaAs quantum wells and heterojunctions (HJ) is studied under a magnetic field (B-parallel to) applied parallel to the two-dimensional electron gas (2DEG) layer. The effect of B-parallel to strongly depends on the electron-hole separation, and we revealed remarkable B-parallel to-induced modifications of the PL spectra in both types of heterostructures. A model considering the direct optical transitions between the conduction and valence subbands that are shifted in k-space under B-parallel to, accounts qualitatively for the observed spectral modifications. In the HJs, the 2DEG-hole PL intensity is strongly enhanced relatively to the bulk exciton PL with increasing B-parallel to. This means that the distance between the photoholes and the 2DEG decreases with increasing B-parallel to, and thus free holes are responsible for the 2DEG-hole PL.