INVESTIGATIONS ON AZO/Al/AZO MULTILAYER STRUCTURE GROWN AT ROOM TEMPERATURE
Abstract
In this work we investigate the effect of metal layer in the Al-doped ZnO (AZO)/Al/AZO structure. AZO and Al thin films are deposed successively at room temperature using DC magnetron sputtering by rotating the substrate holder without breaking the vacuum. The optical characterization of AZO/Al/AZO structure was performed by the spectroscopic ellipsometry under different incidence angles (55∘, 65∘ and 75∘). For the AZO monolayer structure, it was found that the complex refractive index and the complex permittivity coefficient varied differently according to the incidence angle. The addition of Al layer (5nm thicknesses) in this monostructure reduces significantly this influence on the measurement, homogenizes the real refractive index variation and significantly reduces the real electrical coefficient permittivity in the visible range. In addition, the obtained depolarization values confirm the results of the AFM roughness revealing that the Al layer addition makes the surface smoother so that it meets the required conditions as the bottom electrode of organic light emitting diodes. The photoluminescence (PL) measurements indicate that the Al layer alters the PL emission. Actually, the Al layer enhances subsequently the PL emission and promotes the blue and red emission.
