Electron microscopic and X-ray diffraction investigations of nanostructured thin films of ZnO
ZnO films prepared by sol-gel technique using zinc nitrate and zinc acetate as precursor material have been studied using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The results show the formation of zinc oxide phase. The nanostructure of the films was studied by transmission electron microscopy. Nano-structured fine grains of size ranging from 20-60 nm were observed with zinc nitrate precursor film. Individual grains show a sharp contrast with different facets and boundaries. Films prepared by zinc acetate precursor show ultra-fine nano-grains in the shape of dendrites as seen by the TEM. XRD shows a larger size of crystallites with the zinc acetate precursor. Crystal planes and lattice parameters calculated by both electron diffraction and X-ray diffraction are quite close and in agreement with the reported values in literature.
NANOSTRUCTURES IN THIN FILMS OF ZnO
Structure property co-relationship of thin films of ZnO grown by sol-gel spin process using zinc 
acetate and RF magnetron sputtering method has been studied. The films were crystalline in 
nature. The crystallite size for the film grown by sol-gel spin method was found to be of the 
order of 20 nm and that of RF sputtered film was about 30 nm in the c-axis direction of the 
growth. TEM exhibited that the film with uniform microstructure consisted of distribution of 
nanosized grains of the order of 25 nm. Selected area electron diffraction patterns have shown 
the presence of different rings corresponding to different planes of hexagonal ZnO crystal 
structure. The RF sputtered films have shown the formation of nanorods of ZnO which were 
found to have uniform distribution of crystallites of the size ~10 nm.The results would find 
application in nanoelectronic piezoelectric sensors.
Investigation on Synthesis, Characterization, and Electronic Behaviour of Zinc Oxide Thin Films in Relation to Fabrication of Oxygen Gas Sensor
The zinc oxide thin films were prepared by spray pyrolysis method. The films were characterized by means of X-ray diffraction and scanning electron microscopy techniques. The annealing treatment at 300 ± 30 °C for 15 and 30 hours improved the crystallinity of the film and also led to a homogeneous film surface. The O2 gas sensing properties of the zinc oxide thin film were studied by investigating the variation of the electrical resistance of the film as a function of O2 partial pressure at various temperatures. The gas sensing property was found to depend on the film characteristics in regard to its state of crystallinity and surface conditions. The gas sensing property was also dependent on the temperature at which the sensing was done. The optimum oxygen gas sensivity was obtained when the temperature of the zinc oxide sensor was maintained at 400 °C. The study reveals that sprayed zinc oxide thin films may be used as a low cost solid state oxygen gas sensor.