Hot phonon bottleneck

Figure 3.12 Hot phonon bottleneck to slow hot-electron cooling in QWs. At high light intensity, hot electrons produce hot phonons which can reheat electrons via phonon absorption to keep them hot. Pioss is power loss per electron.

QWs, the phonons are confined in the well and they exhibit slab modes (Campos et al, 1992), which enhance the hot phonon bottleneck effect. 

In contradiction to the results showing slowed cooling in QDs, many other investigations are reported in the literature in which a phonon bottleneck was apparently not observed. These results have been reported for both self-organised SK QDs and II-VI colloidal QDs Nozik (2001b) gives a detailed reference list. However, in several cases (Heitz et al., 1991 Heitz et al, 1998 Sosnowski et al, 1998), hot-electron relaxation was found to be slowed, but not sufficientiy for the authors to conclude that this was evidence of a phonon bottieneck. 

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