Influence of annealing on the structural properties of chemically synthesized CdS nano-crystallites

CdS nano-crystallites are prepared through a simple chemical route using mercaptoethanol as an organic capping agent inhibiting the coalescence of nano-particles. The ratio of sulphide (S):mercaptoethanol (SH) is first taken as 1:4 and then varied to 1:3 and 1:2, respectively, to prepare three sets to seek variation in the crystallite size. SEM investigation on the as-prepared samples reveals the nonuniform nature of cluster growth. The influence of annealing on the grain growth at two different temperatures of 100 and 200 °C for 10 min in vacuum is investigated using SEM and XRD analysis. High-resolution TEM and XRD studies indicate an average crystallite size in the range 2–4 nm. The size of the crystallites is found to be less affected by the S:SH ratio, but annealing is found to be responsible for appreciable grain growth. The role of surface modification with annealing is evident in the PL spectra of the CdS nano-crystallites.