EXCITONS IN FUNCTION TO THE BINDING COEFICIENT IN MONOCRISTALLINE SILICON BASE.

Abstract

The exciton is a particle formed between one or more electrons intermediate levels with one or more holes in the valence band. These two particles are bonded by electrical interactions. These interactions are modeled by a coupling coefficient denoted b. Thus in this article, a study of the variation of the excess excitons density in the base in function to the binding coefficient was done. This study shows that, the excess excitons density is zero at the junction of the base and the space charge zone. By cons, in depth, the excitons density increases as a function to the coupling coefficient. Indeed, when one enters deep, interactions between holes and electrons become very important modeled by a high coupling coefficient. These result a reduction of the excess minority carriers mobility in the base and the formation of exciton complexes, hence the increase of the excess excitons density in the base. The reduction of the excess excitons density at the rear face is due to a very high excitons recombination in this region. This is due to a lack adhesion of the metal contact and disruption of the crystal lattice in this region. When the cell is under polychromatic light, the excess excitons density in the base is very high compared to that obtained when the cell is in dark.