PHOTOLUMINESCENCE PROPERTIES OF THE DILUTED MAGNETIC SEMICONDUCTORS ZINC(1-X)MANGANESE(X)SELENIDE AND CADMIUM(1-X)MANGANESE(X)SELENIDE

Time-resolved and cw photoluminescence measurements were carried out on the diluted magnetic semiconductors Zn$\sb{\rm 1-x}$Mn$\sb{\rm x}$Se and Cd$\sb{\rm 1-x}$Mn$\sb{\rm x}$Se; high manganese concentration was emphasized. Zn$\sb{\rm 1-x}$Mn$\sb{\rm x}$Se samples with 0 $\le$ x $\le$ 0.49 were investigated; four emission bands at $\sim2.15$eV, $\sim2.03$eV, $\sim1.95$eV, and $\sim1.35$eV were observed. The bands of $\sim2.15$eV, $\sim2.03$eV, and $\sim1.95$eV were ascribed to Mn$\sp{2+}$ $\sp4$T$\sb1$ $\to$ $\sp6$A$\sb1$ intraion transition, self-activated emission, and copper related emission, respectively. The temperature dependences and decay characteristics of these three bands were investigated for 18 $\u3c$ T $\u3c$ 136K. The $\sim2.15$eV band decays monotonically, while the $\sim2.03$eV and $\sim1.95$eV bands show a slow build up effect, the latter effect indicating the presence of energy transfer in the excitation of these two bands. Thermal quenching of the $\sim2.03$eV and $\sim1.95$eV bands occur below 60K. An energy level scheme is suggested which takes into account mechanisms proposed for similar emissions in ZnSe. Time-resolved measurements on the $\sim2.13$eV and $\sim1.35$eV photoluminescence bands in Cd$\sb{\rm 1-x}$Mn$\sb{\rm x}$Se were carried out for 18 $\u3c$ T $\u3c$ 300K and selected excitation energies 2.035eV $\u3c$ h$\nu\sb{\rm ex}$ $\u3c$ 2.36eV. The $\sim2.13$eV band is observable in an x = 0.48 sample; its decay is monotonic. For samples with x = 0.28 and x = 0.48, the $\sim1.35$eV band exhibits complicated build up processes. A phenomenological model is presented which gives good agreement with data for the $\sim2.13$eV emission. The model ascribes the $\sim2.13$eV emission to the Mn$\sp{2+}$ $\sp4$T$\sb1$ $\to$ $\sp6$A$\sb1$ transition, and assumes a two-level system and energy transfer between these levels. The excitation results on the $\sim1.35$eV emisison suggest that the energy transfer from Mn $\sp4$T$\sb1$ excited states is an important source of excitation of this band for h$\nu\sb{\rm ex}$ $\u3e$ 2.3eV, but two photon excitation of the $\sim2.13$eV band or a similar mechanism is needed to explain the results of h$\nu\sb{\rm ex}$ $\u3c$ 2.3eV