Relative stability of negative and positive trions in model symmetric quantum wires

Binding energies of negative sX−d and positive trions sX+d in quantum wires are studied for strong quantum confinement of carriers which results in a numerical exactly solvable model. The relative electron and hole confinement have a strong effect on the stability of trions. For equal hole and electron confinement, X+ is more stable but a small imbalance of the particle confinement towards a stronger hole confinement, e.g., due to its larger effective mass, leads to the interchange of X− and X+ recombination lines in the photoluminescent spectrum as was recently observed experimentally. In case of larger X− stability, a magnetic field oriented parallel to the wire axis leads to a stronger increase of the X+ binding energy resulting in a crossing of the X+ and X− lines.