Low-resistivity nitrogen-doped p-type Cu2O thin films enabled by millisecond flash lamp annealing

Flash lamp annealing (FLA) provides millisecond-scale thermal processing, but its effects on p-type Cu₂O and nitrogen-related defects remain poorly understood. Reactively sputtered Cu₂O:N films without nitrogen content and with different nitrogen content were deposited using reactive high-power impulse magnetron sputtering and exposed to a single 1.9 ms FLA pulse at 4.9–11.7 J cm⁻². Their compositional, morphological, structural, vibrational, electrical, and optical responses were evaluated. WDS showed no statistically significant change in total elemental composition, and XRD confirmed retention of cubic Cu₂O. Nitrogen-containing films exhibited surface coarsening, shifts of the Cu₂O reflections, and non-monotonic changes in the Raman band assigned to molecular N₂. Nitrogen incorporation substantially reduced the as-deposited resistivity. The very low value of 4.5 × 10⁻² Ω cm was obtained after FLA at 4.9 J cm⁻², whereas higher energy densities markedly increased resistivity, which is caused by increasing hole mobility but decreasing their concentration. At high energy densities, the optical band gap of nitrogen-rich films widened. The results show a narrow processing window for low-energy FLA with a positive effect on electrical properties. High-energy FLA modifies the structure, optical absorption edge and degrades electrical conductivity, which is close to undoped films.