Modeling recombination at the Si-Al2O3 interface

We present a complete set of data on the surface passivation parameters of APCVD Al₂O₃ deposited with TEDA-TSB and H₂O precursors at temperatures between 325 and 520 °C. Using measured values of the fixed charge Q_f, and of the interface defect density D_it(E), electron capture cross-section σ_n(E) and hole capture cross-section σ_p(E) as a function of the energy within the bandgap E, we calculate surface recombination velocities using the SRH model and compare these to measured values, finding excellent agreement when Q_f is large, and reasonable agreement otherwise. It is shown that for typical values of Q_f, recombination is dominated by a single defect species located just below midgap. These results confirm the direct correspondence between Q_f, D_it(E), σ_n(E) and σ_p(E) determined by capacitance and conductance measurements of MIS structures and the carrier lifetimes measured by photoconductance.