NANOCRYSTALLINE ALUMINUM DOPED ZINC OXIDE COATED FIBER OPTIC FOR ULTRAVIOLET DETECTION

Abstract

In this paper, we report the fabrication and characterization of an ultraviolet sensing by using Al -doped ZnO films coated on quartz slide and silica fiber optic. Undoped ZnO , 0.5, 1, 2 and 3 at.% of Al were prepared by sol–gel method with annealing temperature of 400°C for 1 h. The presence of spherical shaped nanoparticles and hexagonal (wurtzite) structure were detected for Al doped ZnO by using FESEM and XRD. The band gap values increased by adding Al due to the increment of carrier concentration. I–V curves reveal an ohmic line and improvement in electrical conductivity when the samples are illuminated by ultraviolet (UV) light with a wavelength of 365 nm. At 1 at.% of Al , the film have a larger increment in photocurrent response when illuminated with UV light compared to undoped ZnO and higher concentration (2 at.% and 3 at.%) of Al . For coated fiber optic, the fiber operates under leaky mode and the refractive index of ZnO is decreasing under UV radiation. There is a small drop in output intensity and increased abruptly which depends on the changes of ZnO refractive index. The thin films have a longer recovery time than response time.