Abstract
The optical properties of a high quality bulk , thermally post treated in a forming gas environment are investigated by temperature dependent continuous wave and time-resolved photoluminescence (PL) measurements. Several bound and free exciton transitions along with their first excited states have been observed at low temperatures, with the main neutral-donor-bound exciton peak at having a linewidth of and dominating the PL spectrum at . This bound exciton transition was visible only below , whereas the A-free exciton transition at persisted up to room temperature. A-free exciton binding energy of is obtained from the position of the excited states of the free excitons. Additional intrinsic and extrinsic fine structures such as polariton, two-electron satellites, donor-acceptor pair transitions, and longitudinal optical-phonon replicas have also been observed and investigated in detail. Time-resolved PL measurements at room temperature reveal a biexponential decay behavior with typical decay constants of and for the as-grown sample. Thermal treatment is observed to increase the carrier lifetimes when performed in a forming gas environment.
1 More- Received 27 October 2003
DOI:https://doi.org/10.1103/PhysRevB.70.195207
©2004 American Physical Society