We present high-resolution photoluminescence data for Si doped with Al, Ga, and In. We observe emission lines due to recombination of electron-hole pairs in bound excitons and satellite lines which have been interpreted in terms of complexes of several excitons bound to an impurity. The bound-exciton luminescence in Si:Ga and Si:Al consists of three emission lines due to transitions from the ground state and two low-lying excited states. In Si:Ga, we observe a second triplet of emission lines which precisely mirror the triplet due to the bound exciton. This second triplet is interpreted as due to decay of a two-exciton complex into the bound exciton. Similar results are found for Si:Al and Si:In. The energy of the lines shows that the second exciton is less tightly bound than the first in Si:Ga. Other lines are observed at lower energies. The bearing of these results on the question of the existence and properties of bound multiexciton complexes is discussed.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics