The results of studies on FeS2 nanorods and ZnS nanoparticles were presented. In semiconductor nanoparticles, there were positron trapping sites within the grains also and these were characterised by using appropriate models on the measured positron lifetimes. Marked changes in the measured positron lifetimes and Doppler broadened gamma-ray spectral line-shapes were observed during structural transformations prompted by substitutional effects in Mn2+-doped ZnS nanorods. The nanoparticles did not exhibit the transformation; implying that the morphologies of the nanosystems plaed a decisive role. The quantum confinement effect in CdS nanoparticles was another phenomenon that could be seen through positron annihilation experiments. Coincidence Doppler broadening measurements were useful to identify the elemental environment around the vacancy clusters that trap positrons. Recent studies of nanocrystalline oxide and sulphide semiconductors were also considered.

Probing the Defects in Nano-Semiconductors using Positrons. P.M.G.Nambissan: Journal of Physics - Conference Series, 2011, 265[1], 012019