ABSTRACT
Great progress has been made on the physics of trions in wide quantum wells over the last decade [6-15], and recently in self-assembled QDs. [16] However, as for excitons, the ensemble spectrum is inhomogeneously broadened. Here we demonstrate complete quantum confinement of a trion by using monolayer-high islands at the interfaces of modulation-doped narrow quantum wells to confine trions in three-dimensional QD-like potentials. This has allowed us to apply the methodology of single QD spectroscopy to probe individual trions in detail. In so doing we identify distinctive signatures in the fine structure of their magneto-optical spectra. The great reduction in linewidth in going from the spectrum of an ensemble to that of single trions enables the fine structure of the trion to be fully resolved. We compare the fine structure spectra of a trion to that of a neutral exciton in a magnetic field.
