Dynamics of paraexcitons generated in a 3D confined potential well by two-photon resonance excitation in Cu2O

Time-resolved emission spectra of orthoexcitons in Cu2O are measured at 1.6 K under two-photon selective excitation in space and energy. SHG scattering and luminescence associated with orthoexcitons can be discriminated by their time domain and directionality. The spatial distribution of the excitons in a stress-induced trap is estimated from time-integrated spectra. Paraexcitons are found to reach the bottom of the potential well while orthoexcitons diminish on the way. These are consistent with the measured decay time of emission bands associated with the excitons.