Structural and spectroscopic properties of ZnO thin films with chaotic surface nanostructures

The study examined the effects of nanomorphologies on electrical conductivity, Raman modes, and photoluminescence in two ZnO films grown by oxidizing metallic Zn on glass substrates. The first film, ZnO-TH1, exhibited distinct nano-granules, while the second film, ZnO-TH2, displayed highly crystalline, chaotic nanostructures, indicating potential applications in optoelectronics. X-ray diffraction analysis revealed a hexagonal wurtzite structure with a space group of P63mc. The films' electrical conductivity was temperature-dependent, with thermally activated conduction and variable-range hopping as the primary conduction mechanisms. The near-edge absorption ratios and Urbach energies were associated with reduced structural disorder and defect energy levels. The orientation of low-dimensional ZnO nanostructures significantly influenced the position, shape, and width of Raman spectral bands. The synthesized ZnO demonstrates potential for solid-state LED applications due to its nanoscale morphologies.