Effect of in-plane magnetic field on the photoluminescence spectrum of modulation-doped quantum wells and heterojunctions

Abstract

The photoluminescence (PL) spectrum of modulation-doped GaAs/AlGaAs quantum wells (MDQW) and heterojunctions (HJ) is studied under a magnetic field ($B_{\Vert }$) applied parallel to the two-dimensional electron gas (2DEG) layer. The effect of $B_{\Vert }$ strongly depends on the electron-hole separation ($d_{eh}$), and we revealed remarkable $B_{\Vert }$-induced modifications of the PL spectra in both types of heterostructures. A model considering the direct optical transitions between the conduction and valence subband that are shifted in k-space under $B_{\Vert }$, accounts qualitatively for the observed spectral modifications. In the HJs, the PL intensity of the bulk excitons is strongly reduced relatively to that of the 2DEG with increasing $B_{\Vert }$. This means that the distance between the photoholes and the 2DEG decreases with increased $B_{\Vert }$, and that free holes are responsible for the hole-2DEG PL.

6pages, 5figures