On the radiative recombination in ZnIn2S4

A detailed study of the ZnIn2S4 photoluminescence in the temperature range 10 to 450 K is presented; the emission spectra consist of a single, wide and asymmetrical band centered, for T = 80 K, at 1.6 to 1.8 eV. The temperature dependence of its peak energy and of its halfwidth shows an unusual behaviour. The emission band shifts towards lower energies when the excitation intensity decreases; in time resolved spectra, a red shift is also observed when the delay time after the end of the pulsed excitation increases. It is shown that these trends, typical of heavily doped semiconductors, can be interpreted only assuming that ZnIn2S4 has a “quasi disordered” nature; this characteristic of ZnIn2S4 is also suggested by the analysis of its optical, electrical, and photoelectronic properties. Finally, a semiempirical model allowing a satisfactory fit of the emission band shape is presented.