Classical-quantum crossovers in quasi-one-dimensional electron-hole systems: Exciton-Mott physics and interband optical spectra

We study quasi-one-dimensional electron-hole (e-h) systems by applying a self-consistent screened T-matrix approximation (SSTA), which can treat an e-h pair embedded in the background of the exciton-plasma mixture, characterized by the exciton ionization ratio. Two classical-quantum crossovers are found. The first crossover takes place as the drastic suppression of ionization ratio, representing the onset of the quantum dissociation of the exciton (binding-energy reduction and level-broadening effects). The second one can be seen in a gradual change in the interband absorption-gain and photoluminescence spectra: Moss-Burstein effects become significant, and the e-h plasma starts to dominate the optical gain. Most of the features of the absorption-gain spectra observed in the recent experiments can be captured semiquantitatively by our SSTA.