Infrared study of free carriers in X/ZnO (XÂ =Â semiconductor, metal) nanocomposites

The infrared (IR) reflectance spectroscopy technique was used for the qualitative determination of free carrier density in metal and semiconductor nanocluster embedded ZnO films. The effects of incorporation of metal and semiconductor nanoclusters on the evolution of the free carrier absorption band in the nanocomposites were studied. Our results reveal that the concentration of free carriers in the composite films depends strongly on the nature of incorporated clusters in the matrix and the annealing temperature. It is demonstrated that just by monitoring the position of a single IR reflectance band, the extent of oxidation of any incorporated species in ZnO can be monitored qualitatively.