Time-resolved photoluminescence, charge-carrier

More recently time-resolved techniques have been applied for studying photocarrier dynamics at the semiconductor-liquid interface. One of the main motivations is that such studies can lead to an estimation of the rate at which photo-induced charge carriers can be transferred from the semiconductor to a redox acceptor in the solution. This method is of great interest because rate constants for the transfer of photocarriers cannot be obtained from current-potential curves as in the case of majority carrier transfer (Section 7.3.5). The main aim is a detailed understanding of the carrier dynamics in the presence of surface states. The different recombination and transfer processes can be quantitatively analyzed by time-resolved photoluminescence emitted from the semiconductor following excitation by picosecond laser pulse. Two examples are shown in Fig. 7.60 [82, 83]. 

Earlier, the lifetime of charge carriers in GaAs superlattices was determined from the time-resolved photoluminescence spectra [3]. Changes in the total and radiative lifetimes were analyzed in the model with no k-selection rule and possible broadening effects. In spite of this, the predictions agree qualitatively with the observed increasing of the lifetime within the red shift of the decaying luminescence spectra. 

While there have been reports of time-resolved photoluminescence [65-68] and electroluminescence experiments [69-71] for the study of recombination, trapping and detrapping of photogenerated charge carriers, potential modulation has scarcely been used. An illustration of the possibilities of this approach is provided by... 

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