The structural, optical and surface morphological properties of zinc oxide layers grown by SILAR method

Abstract

Zinc oxide (ZnO) layers were grown on glass substrates by Successive Ion Layer Adsorption and Reaction (SILAR) method using 0.1M zinc acetate in distilled water as cationic solution. The obtained layers were dried and some of the samples are annealed at 450°C for a holding temperature of 2 hours. The X-ray diffraction analysis revealed that the samples are ZnO with hexagonal wurtzite structure. The lattice parameters were calculated and are very close to the standard values. The annealing has changed the preferential orientation of the layer.The Infrared (IR) studies suggested that the Zn-O stretching happens at around 468 cm−1 for both samples.. The samples were analyzed using UV- Visible spectroscopy. It is noted that the optical transmission decreases with annealing. Maximum transmission was found to be 6% at around 850 nm. To identify the near band edge and defect related emission properties of the samples, the Photo Luminescence (PL) spectroscopy is employed. The as deposited sample showed a broader luminescence spectrum owing to its defects and poor crystallanity, while the annealed sample has a well-defined peak centered around 388nm owing to near band edge emission. A small peak is also shown by the same sample around 579nm, which may be defect related one. The surface irregularities and non uniform crystallisation over the surface of the layers has been observed in Scanning Electron Micrograph images and has been again confirmed in Atomic Force Microscopy (AFM) characterisation. This surface roughness could explain the poor transmission of the samples.