Interface recombination parameters of atomic-layer-deposited Al2O3 on crystalline silicon

We measure the energy-dependent interface recombination parameters at the c-Si/Al2O3 interface using the frequency-dependent conductance technique. The hole capture cross section σp = (4 ± 3) × 10^-16 cm² is energy-independent, whereas the electron capture cross section σn shows a pronounced energy dependence and decreases from (7 ± 4) × 10^-15 cm² at midgap over two orders of magnitude toward the conduction band edge Ec. The capture cross section ratio at midgap is highly asymmetric with σn/σp = 5–70. The interface state density Dit is of the order of 1 × 10¹¹ eV^-1 cm^-2 at midgap. Besides the main defect, a second type of defect with a capture cross section below 10^-19 cm² is resolved near the valence band edge. Numerical calculations of the injection-dependent effective surface recombination velocity using the measured interface recombination parameters show an excellent agreement with experimental data measured using the photoconductance technique.