Time-resolved exciton photoluminescence in GaSe and GaTe

Abstract
Time-resolved photoluminescence measurements of the layered semiconductors GaSe and GaTe have been made using a mode-locked dye laser a synchronously scanning streak camera. It is shown that at low excitation densities (1015-1017 cm-3) exciton dynamics is dominated by trapping at defects. A rate equation model is developed that describes exciton formation, recombination and trapping. At 4K the authors determine free-exciton recombination times at 200 ps for GaTe and 350 ps for GaSe. Trapping times of 200 and 900 ps yield capture cross sections of 1.2*10-14 cm2 and 3.6*10-15 cm2 for GaTe and GaSe respectively.

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