Concentration quenching and migration of excitations in a bulk Cd0.5Mn0.5Te crystal

The curves of intracenter luminescence decay for Mn(2+) ions in the Cd(0.5)Mn(0.5)Te semiconductor solid solution, obtained in a low-temperature experiment, have been simulated by the Monte Carlo method. The features of the kinetics of the 2-eV band in the time interval where significant nonexponentiality of relaxation at different points of the emission band profile manifests itself, as well the integral kinetics and energy relaxation, have been considered. Migration of ion excitations and concentration quenching (which was previously disregarded) are considered to be the main mechanisms determining the kinetic curve formation. It was established that excitation by 2.34-eV photons leads to both selective (intracenter) and band excitation of Mn(2+) ions. Comparison of the results of numerical simulation and experiment showed that the characteristic values of the migration and quenching rates (W(m) and W(q) , respectively) are close in magnitude and W(q,m) approximate to 0.1/tau, where tau is the lifetime at the long-wavelength band wing with the exponential kinetics. The estimated quantum yield (0.56) indicates significant influence of the concentration quenching on the 2-eV luminescence quantum yield in Cd(1-x)Mn (x)Te and Zn(1-x)Mn(x)S crystals with a high concentration of Mn(2+) ions.