Photoluminescence measurements were carried out on Be δ-doped GaAs/Al0.33Ga0.67As heterostructure at 1.6 K in magnetic fields (B) up to 5 T. Luminescence originating from recombination of a two-dimensional electron gas (2DEG) and photo excited holes localized on Be acceptors was analyzed. The degree of circular polarization (γC) of the luminescence from fully occupied Landau levels was determined as a function of B and the 2DEG concentration, ns. At B constant, γC decreased with the increase of ns. Two mechanisms of the γC(ns) dependence are discussed: a) the Stark effect on a photo excited hole bound to Be acceptor and b) the in-plane anisotropy of the intensity of optical transitions. A quantitative analysis shows that the influence of the Stark effect on γC is negligible in the present experiment. We propose that the γC(ns) dependence results from the C2v symmetry of conduction band electron wavefunctions and we give qualitative arguments supporting this interpretation.
@article{arxiv.cond-mat/0703088,
title = {In-plane optical anisotropy due to conduction band electron wavefunctions},
author = {J. Łusakowski and M. Sakowicz and K. J. Friedland and R. Hey and K. Ploog},
journal= {arXiv preprint arXiv:cond-mat/0703088},
year = {2007}
}