Today, the technological development that has been concentrated on the front 99% on the use of silicon as a base material for the photovoltaic industry [1], went even further by exploiting other materials such as layered oxides thin and more particularly the oxides of semiconductors. These materials are very have found various applications, for example we mention SAW-based thin films of ZnO [2, 3], for electroacoustic sensor technology. Zinc oxide (ZnO) is a direct gap material [4], the gap at room temperature of ZnO can be placed in the range 3.2 to 3.3 eV [5].

The main advantage of ZnO is the fact that its components are non-toxic and very abundant on Earth [6]. ZnO is part of the family of transparent semiconductor oxides and has a high absorption and diffusion of ultraviolet radiation. Zinc oxide is a transparent material whose refractive index is equal to 2. In the form of a thin layer, the refractive index and the absorption coefficient vary according to the production conditions. The refractive index of Thin ZnO varies between 1.90 and 2.20 [7]. The optical properties of thin films are strongly dependent on the elaboration method, the quality of the layers, the heat treatment applied, the type and concentration of the dopant [8].

The deposition procedure (sol-gel) (dip-coating) makes it possible to obtain coats of ZnO that are rough and thus effectively scatter the light that passes through them. Thin layers of ZnO allow to lengthen the path that the light so the optical parameters studied are measuring: the optical gap, the disorder the index of refraction.

We studied the influence of the elaboration method on the optical properties of the ZnO layers; we realized 2 series of samples that we characterized on the optical level,