Tailoring the band gap of ZnO nanostructures using chromium

Nanostructured pure and Chromium doped ZnO thin films were grown on glass substrates by spin coating technique. Structural, electrical and optical properties of these thin films have been investigated by X-Ray diffraction, UV–Visible spectroscopy, scanning electron microscope, Raman spectroscopy and I–V measurements. XRD patterns show that the particle size varies with respect to the varying concentration of Chromium. The lattice parameters, bond length and the average particle size have also been determined from the XRD data. The SEM images of the nanostructured thin film of doped and undoped ZnO shows the uniformly grown nanoparticles and uniform layer deposition of thin film. For dopant concentrations less than 2.5%, the optical band gap is found to be increase with increase in Cr concentration due to reduction in grain size. Raman spectroscopic studies confirm the hexagonal wurtzite structure formation of the ZnO nanoparticle. The electrical transport properties of the nanostructured thin films correlate well with the variation in the bandgap.