Publicado 12 números por año
ISSN Imprimir: 0040-2508
ISSN En Línea: 1943-6009
Indexed in
Effect of Generation and Recombination of Excitons on Static Characteristics of Injection Lasers
SINOPSIS
The effect of excitons on the emission dynamics of semiconductor lasers has been considered by V.S.Mashkevich in papers [1,2]. The possibility of laser type emission based on radiative recombination of excitons in heterojunction lasers was demonstrated by P.G.Yeliseyev [3]. The lasing effect owing to exciton radiative recombination mechanism was first performed in the semiconducting AIIBIV compound by V.P.Grybkovski who investigated it in detail [4]. That allowed the following tendencies to be predicted and practically confirmed: a) exciton transitions can be used as the pumping channel for exciting the semiconductor laser by another laser; b) light absorption by excitons and exciton absorption contribute significantly to reabsorption losses and c) binding of free carriers into exciton pairs prevents population inversion, which is particularly pronounced in the pre-threshold region. However, of greatest interest is the effect of lasing by radiative exciton transitions. First, the exciton mechanism of radiative recombination is remarkable in that the energy of a radiated quantum is less than the forbidden zone energy and lies outside the intrinsic absorption region of the crystal, i.e. in the region of transparency. The reason is that the energy exchange occurs with participation of the exciton binding energy and the energy of one or more phonons. Second, the expansion of injection laser diodes (ILD) involving quantum-size structures (QSS) based on complex triple or quadruple semiconducting compounds stimulates the need for a revision of the band theory of semiconductors in terms of principles of quantum mechanics. Specifically, quantum-size structures enable localizing a great number of carriers in a small volume and reducing the volume spreading to a minimum. The self-energy of carriers is quantized in quantum-size layers, thereby neutralizing the volume degeneration of energy bands in the crystal. Under such conditions the character of the field-particle interaction is significantly different from that of the ordinary (bulk) semiconductor with parabolic bands. Besides, the binding energy of excitons is much higher in quantum-size structures and depends only slightly on temperature; excitons can live without decay up to 200C and the mechanisms of their formation and annihilation are modified. The effect of excitons on lasing processes in the ISL with the QSS has attracted an increasing attention of researchers [5].