Air-annealing-induced vertical elemental gradients regulate defect chemistry and optoelectronic properties of cylindrical-target-sputtered ITO thin films

At 250 °C, air annealing balances surface oxygen passivation, interior donor retention and suppressed substrate diffusion, yielding low sheet resistance (22.5 Ω sq ⁻¹ ) with 89.8% visible transmittance.