Three Dimensionally Diluted Magnetic Semiconductor Clusters Cd₁_-<i>_y</i>Mn<i>_y</i>S with a Range of Sizes and Compositions:  Dependence of Spectroscopic Properties on the Synthesis Mode

Abstract

Absorption and photoluminescence spectroscopic measurements are presented for particles with sizes from 2 to 4 nm, composition from y = 0 to 0.3,where y is given by Cd 1 - y Mn y S, and different preparation modes. No monotonous variation of bandgap energy with increasing composition is observed. The depth of the minimum increases with decreasing particle size. This is attributed to a marked increase in the interactions between the Mn 2+ d electrons and the valence and conduction band electrons. Mn 2+ photoluminescence is observed at 77 K, when the particles are aged in the solution. Otherwise only the trap emissions due to CdS defect states are seen. Certain preparation modes favor Mn 2+ photoluminescence at room temperature.