Time-Resolved Photoluminescence Spectra in Single Crystals of CuAlS2:Mn

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Abstract
Time-resolved spectra were measured in single crystals of CuAlS2 doped with different concentrations of Mn, as well as in an undoped crystal, to elucidate the recombination mechanisms associated with the red photoluminescence band at 1.96 eV. The 0.01 wt% Mn-doped sample shows a broad emission band around 2.5 eV, 25 ns after the excitation, which loses intensity rapidly, transferring energy to an infrared peak. At 10 µs both bands are quenched, leaving the red band at 1.96 eV. On the other hand, the PL spectrum in 1 wt% Mn-doped samples at 25 ns consisted of a purple peak at 3 eV and a red peak at 1.96 eV. The purple PL peak relaxed rapidly with a decay time of 50 ns, while the red peak showed a slow decay with a time constant of 100 µs. The possibility of energy transfer between the host impurity/defect states and the Mn ion is discussed.