Titanium doped copper oxide thin films via dc magnetron sputtering for Schottky barrier devices

This work presents the deposition and characterization of pure and Ti-doped copper oxide thin films on glass substrates using reactive DC magnetron sputtering, with oxygen flow rate as the key tuning parameter. Structural, morphological, optical, and electrical properties were systematically studied. XRD confirmed a phase transition from paramelaconite (Cu₄O₃) to monoclinic CuO with increasing oxygen flow, while Ti doping further modified structural and electronic properties. SEM and AFM revealed uniform, dense, defect-free films with decreasing roughness (3.92–1.22 nm) at higher oxygen flow. After Ti doping, the optical band gap increased from 1.82 to 2.19 eV, while PL indicated enhanced oxygen interstitial defects. XPS validated the presence of Cu₄O₃ at lower flow and pure CuO at higher flow, which is consistent with XRD. Electrical studies confirmed stable p-type conductivity and Schottky behavior, with barrier heights varying with oxygen flow and doping. To examine the metal-semiconductor Schottky behavior, current-voltage measurements were performed and analyzed using the Cheung and thermionic emission models. As the O₂ flow varied, the barrier height slightly changed from 0.60 to 0.61 eV in the Thermionic Emission (TE) model and from 2.41 to 0.88 eV in the Cheung model. These findings establish strong structure–property correlations and demonstrate a scalable, cost-effective route for tailoring CuO- and Ti:CuO-based thin films. The optimized films hold promise for optoelectronic and energy applications, including thin-film transistors, integrated circuits, solar cells, sensors, and photodetectors.