Ground and excited states associated with donor bound-excitons in high purity GaAs

Abstract

Four emission lines have been observed in high purity GaAs, which are associated with excitons bound to a shallow neutral donor. The lowest energy line is the ground state; the three higher energy lines are due to excited states of the neutral donor-bound exciton. The excited states consist of a rotation of light and heavy holes around the donor as was previously observed in InP. The experimentally observed energy ordering of the two exited states associated with the light-hole was previously found to be reversed from that predicted by theory for the case of InP. In the case of GaAs, the present work shows that the ordering of these two states agrees with the ordering predicted by theory. Two additional excited states were also observed; they may be associated with the next higher rotational quantum state ( l = 2).