Cr₂O₃–NiO mixed oxides thin films for p-type transparent conductive electrodes

The Cr₂O₃–NiO mixed oxides’ thin films were formed by means of the layer-by-layer magnetron sputtering deposition of Cr₂O₃, NiO, and Cr₂O₃ layers on c-plane sapphire substrates. These thin-film structures, subjected to subsequent annealing, constituted a combination of the monocrystalline (0001) Cr₂O₃ and nonordered nickel oxide phase, which was a mixture of NiO and Ni₂O₃. The annealing at 900 and 1000 °С in air facilitated the diffusion of Ni and Cr atoms into the layers. Varying the annealing time allowed us to control the uniformity of the Ni and Cr distribution, the microrelief of the film surface, the transmittance in the visible region, and the sheet resistance of the Cr₂O₃–NiO thin-film structures. Thus, the films annealed at 900 °C during 30 min were characterized by a uniform distribution, a relatively weakly developed surface, a low sheet resistance, and the highest Haacke's Figure of Merit of 1.49 × 10^–9 Ω^–1. The formation of mixed Cr₂O₃–NiO oxides by the proposed approach was found to be an effective way to improve the performances of Cr₂O₃ based p-type transparent conductive electrodes.