Structural, optical and cathodoluminescence characteristics of undoped and tin-doped ZnO thin films prepared by spray pyrolysis

摘要

Cathodoluminescence (CL) spectroscopy, X-ray diffraction and spectrophotometery have been studied of undoped and tin (Sn)-doped ZnO films prepared by spray pyrolysis (SP) technique of zinc chloride and tin chloride. The luminescence films had a polycrystalline hexagonal wurtzite type structure. At room temperature, the cathodoluminescence (CL) spectra of the undoped and doped ZnO films exhibit the common near ultra-violet (UV) band-gap peak at l = 382 nm but they differ as regards their visible emissions. The undoped ZnO emits an intensive blue-green light (L = 520 nm) and a red emission (L = 672 nm). The presence of tin gives rise to a new light emission corresponding to L = 463 nm and the extension of blue-green light typical of the intrinsic behavior of the material. CL imaging of undoped ZnO films show that the luminescence is located at defined sites giving rise to a grain-like structure inherent to the surface morphology. The presence of tin in the material leads to great luminescent spots, attributed to large grain sizes. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 34]