Breakdown of the Momentum Conservation Rule

A very general effect of quantum confinement in semiconductors is a widening of their optical band gap. For the model system of an infinite-barrier 2-D quantum well, (3.1) shows that the lowest energy (A = 1) of a con- 

The strong-confinement regime corresponds to the opposite limit, 2flQ.In that case the relative electron-hole motion is strongly affected by the barriers. In the direction of restricted motion, the kinetic energies of the lowest-energy electron and hole states determined by the quantum confinement are larger than the Coulomb 

3 -3 Observed values of energy shifts in the luminescence peak of CuCl nanocrystals in NaCl (circles) and in the absorption peak of CdS nanocrystals in silicate glass (triangles), compared with theoretical models weak-confinement model (dashed-dotted lines), strong confinement model (short-dashedline) r = mjj /m J is considered as a fixed parameter. (After [3.25]) 

Another consequence of the large oscillator strengths associated with confined-exciton transitions is the 

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