Quantum dots optical gain

Ideal semiconductor quantum dot structures should exhibit a delta-function-like (atomic-like) density-of-states for both electrons mid holes [4], Optical excitations in such structures are excitonic in nature, since an electron mid a hole confined in a quantum dot necessarily interact via their Coulomb interaction mid, therefore, form mi exciton. Consequently, a single electron-hole pair in a quantum dot corresponds to mi exciton, whereas doubly occupied electron and hole states (both spin states) correspond to a biexciton. Since the Coulomb interaction of the particles is inevitable, it makes no sense to distinguish between excitons mid free electrons mid holes within a quantum dot. Optical gain... 

FIGURE 4 Optical gain of unstrained zincblende GaN/Alo 2Ga<> N single quantum wells with well length Lz being 60 A The solid and dotted lines stand for the results for TE- and TM-modes. respectively. 

Before discussing the experimental evidence, it is worthwhile to consider lasing-related properties of quantum dots from a fundamental point of view. The theoretical description of the optical gain in bulk and quantum well semiconductors is discussed in Datareview C5.3. 

M. G. Bawendi Optical gain and stimulated emission in nanocrystal quantum dots. Science 290, 314-317 (2000)... 

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