Optical, structural, and electrical characteristics of ZnO films co-doped with Al and In elements for TCO applications

The optical, structural, and electrical characteristics of ZnO films co-doped with Al and In elements are investigated. The films were prepared by spray pyrolysis with a permanent In content and Al concentrations of 0.5–3.5 at.%. The film structure was wurtzite and a transmittance of 89–90% was detected in the visible spectral range. By doping atoms with lower (Al) and larger (In) ion radii compared to Zn, residual stresses are reduced, allowing the self-compensating process to shift toward higher donor concentrations and achieve electrical resistivity of 3.0 × 10⁻³ Ω cm. Reasons for the non-monotonic changes of characteristics are discussed. Graphical abstract: [Figure not available: see fulltext.].