Abstract

We report on a computer simulation of the radiationless energy transfer¹⁾ between Mn²⁺ -ions in Cd_1−XMn_XTe. The model was applied to explain the photoluminescence properties in this material and in other II-VI-semiconductors with high manganese concentration. An fcc-lattice with 4096 lattice points and periodic boundary conditions is randomly occupied with "active" ions corresponding to a molar concentration x. The active ions are given 2 electronic states with energies E_g and E_e = E_g+ E_O + N ΔE, where N is the number of "active" neighbors. The expression for E_e simulates the random crystal field seen by one active ion. The simulation starts with the excitation of a random active lattice point x. After an internal time interval Δt the excitation either decays with a certain probability W by photon emission or is transfered to a random neighboring active lattice point x′. If it has to step up in energy, the transition probability is to exp $\frac{(E_{\text{e}}(x)-E_{\text{e}}(x\text{'}))}{{\text{k}}_{\text{B}}\text{T}}$, if it steps down, the transition probability is one. This procedure is repeated until the excitation decays radiatively with energy E(x′) after n time intervals Δt. After 500 000 excitations the time resolved spectrum is determined from E(x′) and n, which is equivalent to the delay time in the time resolved luminescence experiment. The spectra depend on temperature and delay time.

© 1984 Optical Society of America