Effect of annealing on the properties of chemical bath deposited nanorods of CdSe thin films

Cadmium selenide (CdSe) thin films have been deposited by chemical bath deposition (CBD) on a glass substrate and they are annealed at 450 degrees C for 1 h. Scanning electron microscopic (SEM) image of as-deposited CdSe shows the spherical shaped grains distributed over entire glass substrate. When it is annealed at 450 degrees C, clusters of nano-rods with star shaped grains are formed. The X-ray diffraction (XRD) study of the as-deposited films exhibits a polycrystalline nature and it undergoes a structural phase transition from the metastable cubic to the stable hexagonal phase when annealed at 450 degrees C. Optical band gap of as-deposited films (2.0 eV) has a blue shift with respect to the bulk value (1.7 eV) due to quantum confinement. The band gap energies of the films are decreased from 2.0 eV to 1.9 eV due to annealing at the temperature of 450 degrees C. The electrical resistivity, Hall mobility and carrier concentration of as-deposited and annealed films are determined.