Excitons and charged excitons in semiconductor quantum wells

A variational calculation of the ground-stare energy of neutral excitons an d of positively and negatively charged excitons (trions) confined in a sing le-quantum well is presented. We study the dependence of the correlation en ergy and of the binding energy on the well width and on the hole mass. The conditional probability distribution for positively and negatively charged excitons is obtained, providing information on the correlation and the char ge distribution in the system. A comparison is made with available experime ntal data on trion binding energies in GaAs-, ZnSe-, and CdTe-based quantum well structures, which indicates that trions become localized with decreas ing quantum well width.