Photoluminescence and micro-Raman scattering in Mn-doped ZnS nanocrystalline semiconductors

Using photoluminescence and Raman scattering, we have studied the optical properties of Mn-doped ZnS nanocrystallites prepared by a microemulsion-hydrothermal method. The PL spectrum shows two distinct peaks in the blue-green region. The PL peak from the nanoparticles, in the region 400-480 nm (3.1-2.6 eV), shifts toward the lower energy with decreasing excitation intensity, which shows that the luminescence originates from the donor-acceptor pair recombination. Such self-activated luminescence could involve the Zn vacancies and Mn acceptors. Micro-Raman scattering measurements on these nanostructured ZnS:Mn crystallites show a low-frequency wing at 315 cm(-1) besides the characteristic first-order longitudinal optical phonon at 349 cm(-1). The transverse optical phonon from these nanocrystallites at 269 cm(-1) along with a much weaker vibrational mode near 220 cm(-1) was also observed. (C) 2003 American Vacuum Society.