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

Abstract

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 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 0.045 Ωcm was obtained after FLA at 4.9 J cm-2, whereas higher energy densities markedly increased resistivity. Hall measurements showed increasing mobility but decreasing hole concentration. At high energy densities, the optical band gap of nitrogen-rich films widened. The results define a narrow low-energy processing window with a positive effect on electrical properties, whereas high-energy FLA modifies the structure and optical absorption edge but degrades electrical conductivity.