Optical studies of modulation-doped V-groove quantum wires: Fermi-edge singularity

We report on an experimental study of the optical properties of modulation-doped V-groove semiconductor quantum wires. The Fermi-edge singularity is observed in emission and only weakly in absorption spectra. The conditions necessary for its observation are assessed by varying the electron density and providing the occupation of one, two or three one-dimensional (1D) subbands. We show that the existence of a strong optical singularity is related to both the effect of the hole localization and that of an enhancement induced by Coulomb correlations with a resonance associated with a partially empty 1D subband.