Picosecond Spectroscopy of CdSe at High Excitation

At 4.2 K, the time resolved luminescence is studied of CdSe platelets, using two‐photon excitation at 1.064 μm and monopulsed excitation. At first the importance is shown of lattice heating and quasiparticle heating in high excitation experiments in CdSe. Then, the simultaneous kinetics of the A–LO excitonic line and the so‐called P line is studied. In the experiments, the P line cannot at all be interpreted as resulting of radiative exciton–exciton collisions. It is shown that the previously proposed radiative transition from the Γ1 biexciton ground state to the 2p exciton state provides the best understanding of the dynamical behaviour of the P line. A binding energy of 1.4 meV for the biexciton in CdSe is deduced.