ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The luminescence decay kinetics of homogeneously and delta-doped ZnS:Mn thin film phosphors was investigated. A quantitative model based on the hopping model of energy transfer theory was developed to described the concentration quenching phenomenon in ZnS:Mn. The model predicted the dependence of the energy transfer rate on material parameters such as the Mn and defect concentrations. The luminescence decay of homogeneously doped ZnS:Mn consisted of two exponential components at 10 K. The fast component of 120 μs was attributed to exchange-coupled pair emission and the slow component of 1.6 ms to isolated Mn ions. As the temperature was increased, the exchange-coupled pair emission disappeared and the decay became strongly nonexponential. The nonexponentiality was attributed to nonradiative energy transfer processes. The concentration dependence of the effective lifetime was also found to change with temperature. The investigation on the temperature dependence revealed two regimes of concentration which showed distinct temperature dependencies. From the temperature dependence, it was concluded that the energy transfer between Mn ions was active only when the Mn concentration was greater than 2 at. %. By comparing these results with the results of Dexter's theory, the energy transfer between Mn ions was found to be mediated by an electric dipole–dipole interaction. The delta-doped ZnS:Mn showed faster decay times due to the enhanced overlap between 3d and s-p host states caused by lattice strain. From the temperature dependence, a two-dimensional confinement of energy transfer was observed when the doping planes were far apart. However, when the doping planes were brought close together, the delta-doped samples behaved similarly to the homogeneously doped ZnS:Mn indicating that the energy transfer was no longer two-dimensionally confined. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.368980
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