Impact Ionization and Carrier Multiplication

As shown in previous chapters charge transfer processes at pn-junctions and at semiconductor-liquid interfaces can be enhanced by light excitation. The minimum photon energy required for the corresponding processes is at least the same 

Hot Carrier Cooling and Exciton Multiplication in Quantum Dots 

The analysis of these results is not trivial because similar decays are also observed for photon energies of pj, 2Eq, however, only at high light intensities. The latter means that also biexcitons were formed by direct absorption of two photons within some single nanocrystals. For pulsed laser excitation of a solution of NC of sufficiently short duration so that no carrier recombination occurs during excitation, the fraction of NCs within the excitation volume with m 

During the excitation process, hot electrons and holes are formed. In subsequence there are two processes competing with each other. The hot electrons and holes can either cool down to the lower edges of the energy bands or a bieexcimer is formed. The number oie-h pairs generated per absorbed photon (or quantum yield, QY) can be expressed by the following equation [96]  

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