Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

• Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained.
• Mosaicity between crystalline domains increased with film thickness.
• Lattice parameters a and c diminished linearly as a function of Al concentration.
• First steps for developing porous silicon/doped ZnO heterojunctions were presented.

Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties.