ZnO:In deposition by spray pyrolysis — Influence of the growth conditions on the electrical and optical properties

Indium-doped zinc oxide (ZnO:In) was spray-deposited on glass at a substrate temperature of 370 °C. The spray was generated by means of an ultrasonic nebulizer and using air as carrier gas. To the 0.2 mol/l zinc acetate solution indium acetate has been added as dopant, the [In]/[Zn] ratio was changed between 1 and 5 at.%. The mobility and resistivity have an optimum at an [In]/[Zn] ratio of 3 at.% with values of 2.9 mΩ cm and 12.5 cm²/Vs at a layer thickness of 1.3 μm. The application of a nucleation layer of 100 nm intrinsic ZnO (i-ZnO) on the glass substrate and the subsequent deposition of ZnO:In lead to a layer with significant improvement of the optical properties; the ultraviolet to visible (UV-VIS) light transmittance increased to above 80% in the visible light region. The new layer configuration caused a change in the layer morphology, which is visualised by Scanning Electron Microscope photographs, Energy Dispersive X-ray and X-ray Diffraction measurements. The electrical properties remained unchanged.