Post annealing effect on thin film composed ZnO nano-particles on porous silicon

Abstract

Zinc acetate dihydrate as a starting material was used in precursor preparation. In order to prepare porous silicon (Psi) substrates, electrochemical etching was employed to modify the silicon surface. ZnO thin films were successfully deposited on porous silicon substrate by spin-coating technique. Post annealing temperatures were varied in a range of 300°C to 700°C to investigate its effect on morphologies and photoluminescence proper- ties of the ZnO thin films. Field Emission Scanning Electron Microscopy (FESEM) results revealed that the thin films are composed of ZnO nano-particles and distributed uniformly on Psi surface. ZnO nano-particle sizes are varied from 21.3 nm to 25.9 nm when annealed in different temperatures. Atomic Force Microscopic (AFM) analy- sis was carried out to study the surface morphology. It was found that the lowest average surface roughness of ZnO thin films is obtained at an annealing temperature of 500°C, which is 1.46 nm. Photoluminescence (PL) spectrosco- py was conducted in the range of 350 nm to 900 nm. The result shows three distinct peaks at 410 to 420 nm, 525 to 600 nm and 625 to 725 nm, which are attributed to nano-structured ZnO, ZnO defects and porous silicon respec- tively. © Global Scientific Publishers 2013.