LUMINESCENCE OF THE CR3-TYPE ALPHA-ZNAL2S4-CR SINGLE-CRYSTALS( IONS IN SPINEL)

Photoluminescence (PL) of chromium-doped spinel-type semiconductor alp ha-ZnAl2S4 has been studied in the temperature range 2 - 540 K. The tr ansitions between ground state (4)A(2g) and E-2(g), T-2(1g), T-4(2g), T-4(1g) excited levels of Cr3+ ions in absorption and emission spectra have been observed. A fit of the measured temperature dependence of t he PL decay, using a four-level model, gave the lifetimes of the E-2(g ), T-2(1g) and T-4(2g) levels. The energy gaps between E-2(g) - T-2(1g ) and E-2(g) - (4)T(2)g states have been determined and they are very close to the values obtained from steady-state measurements. A configu rational coordinate diagram for Cr3+ ions in the alpha-ZnAl2S4:Cr spin el host has been constructed.