Electron beam induced structural modification of the oxidized silicon micro-clusters in ZnO matrix

Si/ZnO nano- and micro-composites were grown on SiO(2) glass substrates by co-sputtering technique. The content of Si in the films was controlled by the no. of Si pieces placed on the ZnO target. The crystallinity of the composite films decreased on increasing the Si content in them and increased on post deposition thermal annealing. The dispersed Si in the ZnO matrix remained in the form of nano-particles with an average size value of 3.7 nm and does not depend on the fractional Si content in them. On thermal annealing, the size of the nano-particles did not change noticeably up to 600 degrees C. For the thermal annealing at and above 700 degrees C, the nano-particles aggregated to form micro-clusters with an average size value of 34 nm. The micro-clusters were seen to be crystallized with distinct line structures in the TEM. images and spots in the TED patterns. On high energy electron irradiation, the micro-clusters broke to form nano-particles of similar size as they were before the formation of micro-clusters.