Dark field optical imaging and photoluminescence spectra from ZnO microstructures obtained by spray pyrolysis

In this work we present results on ZnO self-assembled microstructures obtained by modified ultrasonic spray pyrolysis technique. We show optical imaging and photoluminescence spectrum from a typical self-assembled ZnO microstructure grown on Si(100) substrate. The dendritic formation of ZnO clusters achieved with our technique allows us to study both structural defects and heat routes in ZnO films. After thermal treatment, enhanced green and red emissions were observed on PL spectrum of the ZnO microstructures. The energy band gap from a typical structure was 3.13 eV, lower than usual for thick ZnO film, and a clear dependence with substrate surface roughness was also observed.