ZnO thin films with narrow band blue emission grown using sol gel spin coating technique

Abstract

ZnO thin films were deposited on glass substrates using sol gel spin coating method. The effect of substrate rotation speed on the structural and the optical properties of the film were investigated. XRD results confirm all films are of hexagonal wurtzite typestructure. The film at 1500 rpm shows prominent c-axis orientation along the (002) plane. The x-ray diffraction (XRD) patterns indicates that the intensity of (002) diffraction peak becomes stronger with increasing coating speed up to 1500 rpm and then becomes weaker at 2000 rpm. The optical property of synthesized ZnO thin film is evaluated using room temperature PL measurement. The obtained result exhibits a strong near-band-edge (NBE) emission at ∼390 nm and a negligible deep-level (DL) emission at ∼470 nm. The narrow single band emission in the deep level region at 470 nm (2.64eV) corresponds to rare blue emission. An analysis in terms of the effect of rotation speed on blue band emission has been presented to provide more consistency in the results. The results indicate that the as-grown ZnO thin film is an excellent blue light emitter and can be used for blue LED application.