Dynamical Behavior of the High Density Electron–Hole System in CdSe

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Abstract
Time changes of exciton reflection spectra in CdSe under high intensity excitation by picosecond pulses corresponding to band‐to‐band excitation are observed at 2 and 77 K, in order to obtain further information on the dynamical behavior of high density electron–hole plasma. It is found that just after picosecond excitation the exciton reflection structure disappears, but it recovers gradually with the lapse of time, and that the stronger the excitation intensity is, the longer the recovery time becomes. Comparing these results with time‐resolved luminescence spectra observed under the same excitation conditions, it is concluded that as time proceeds, the electron–hole plasma state is transformed to the high density exciton state, and that the luminescence in the late stage is due to the inelastic collision of excitons. It is sure that the formation of electron–hole liquid does not take place.