Charged Excitons in Weakly Doped Quantum Wells
Abstract
Optical absorption and emission spectra of weakly doped, low-dimensional semiconductors are strongly affected by excess carriers. Recent experimental investigations of the lowest excitonic transition in weakly (optically) n-doped quantum wells seem to indicate that at low enough carrier densities negatively charged excitons might appear and contribute to the exciton line-shape (A. Manassen, E. Cohen, Arza Ron, E. Linder, and L.N. Pfeiffer, Phys. Rev. B 54), 10609 (1996). From a theoretical point of view, however, it is not obvious, whether charged excitons (i.e. correlated three-particle complexes made out of two conduction band electrons and one valence band hole) are indeed stable enough to significantly modify the exciton line. To address this problem, we derive, employing a Faddeev-Watson decoupling procedure, an expression for the exciton self-energy, which is exact in the low density limit and contains the relevant three-particle correlations non-perturbatively. We then discuss under what conditions a bound state (or resonance) in the three-particle sector exists and, relating the exciton self-energy to the optical susceptibility, to what extent it eventually distorts the exciton line-shape.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1998
- Bibcode:
- 1998APS..MAR.C2709B