Photoluminescence in Ho-doped AgGaS2 single crystals

Doping of Ho into AgGaS2 has been carried out by the thermal diffusion of Ho element into the undoped crystal. Sharp photoluminescence (PL) lines related to the S-5(2) --> 5I(8) and F-5(3) --> I-5(7) transitions in the Ho3+ ion are observed in the energy regions 2.23-2.28 and 1.85-1.93eV, respectively. Temperature dependence and excitation wavelength dependence of the PL indicate the existence of at least four types of He-related luminescence centers. Moreover, it is found that PL lines from different He-related luminescence centers exhibit different excitation and recombination mechanisms. (C) 2000 Elsevier Science B.V. All rights reserved.