Fabrication and characterization of nano-structured aluminum-doped zinc oxide films

Nanostructured ZnO samples on Si(100) and glass substrates have been synthesized by simple chemical solution method with post-thermal treatments. UV-vis spectrum, Hall measurement, and photoluminescence and scanning electron microscopy (SEM) have been used to characterize nanostructured ZnO thin films at various annealing temperatures. Post-thermal treatment does not only modify the surface morphology but also the intensity ratio of near-band-edge to green emission of ZnO samples. Meanwhile, the ZnO samples exhibited free exciton and very sharp exciton emissions at low temperatures. The average transmittance of nanostructured ZnO in the visible range was above 80 %, and optical band gap increased as increasing the annealing temperature, which might be explained by the Burstein-Moss effect. Experimental results reveal that post-thermal treatment play a key role in the fabrication of ZnO-based photonic devices.