Modeling Recombination at the Si–Al $_{2}$ O $_{3}$ Interface

In this paper, we present a complete set of data on the silicon surface passivation parameters of Al₂O₃ deposited by atmospheric pressure chemical vapor deposition with triethyldialuminum-tri-( sec-butoxide) and H₂O precursors at temperatures between 325 and 520°C. Using measured values of the total interface charge Q_tot and of the interface defect density D_it(E), apparent electron capture cross section σ_n (E), and apparent hole capture cross section σ_p(E) as a function of the energy within the bandgap E, we calculate surface recombination velocities using the Shockley-Read-Hall (SRH) model and compare these with measured values, finding excellent agreement when Q_tot is large and reasonable agreement otherwise. The resulting model is valid for both n- and p-type substrates, under the condition that holes are the majority carrier at the surface, as is generally the case for typical (negative) values of Q_tot. It is shown that, under these conditions, recombination is dominated by a single donor-like defect species located just below midgap. These results support the direct correspondence between Q_tot, D_it (E), σ_n, and σ_p determined by capacitance and conductance measurements of metal-insulator-semiconductor structures and the carrier lifetimes measured by photoconductance.