Modeling recombination at the Si-Al₂O₃ interface

In this paper, we present a complete set of data on the silicon surface passivation parameters of Al ₂O₃ deposited by atmospheric pressure chemical vapor deposition with triethyldialuminum-tri-(sec-butoxide) and H₂ O 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.