Modeling Recombination at the Si–Al₂O ₃ Interface

In this paper, we present a complete set of data on the silicon surface passivation parameters of Al2O3deposited 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 chargeQtotand of the interface defect densityDit(E), apparent electron capture cross section σn(E), and apparent hole capture cross section σp(E) as a function of the energy within the bandgapE, we calculate surface recombination velocities using the Shockley-Read-Hall (SRH) model and compare these with measured values, finding excellent agreement whenQtotis 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 ofQtot. 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 betweenQtot,Dit(E), σn, and σpdetermined by capacitance and conductance measurements of metal-insulator-semiconductor structures and the carrier lifetimes measured by photoconductance.