The lowhyphen;temperature photoluminescence spectra of AgGaS2are investigated in this work. At 4.2deg;K, the luminescence spectra are dominated by many sharp lines as well as broad emission bands. A series of emission lines was found to be superimposed on the broad band peaking at sim; 5000 Aring;. The series of emission lines are attributed to phononhyphen;assisted transitions involving an unidentified impurity or defect. Two basic phonons with energies of 5.4 and 7.2 meV are identified from the phonon structure. The 7.2hyphen;meV mode is also seen in the Raman spectrum. They are tentatively identified as the lattice modes.
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