Modelling the ultraviolet irradiation effect on the effective minority carrier recombination lifetime of silicon wafers

A mathematical model is presented to explain the effect of ultraviolet (UV) irradiation on the minority carrier recombination lifetime (LT) and surfac e barrier observed in thermally oxidized, RCA cleaned, and contaminated sil icon wafers. The proposed model assumes that UV photons (4.9 eV) modify the density of two interface traps and the oxide charge density. It considers the conversion between the two species of traps with energy levels E-1 and E-2, relative to the intrinsic Fermi level (E-i). These modifications direc tly affect the surface recombination velocity and hence the effective LT. T he changes in the effective lifetime and the surface barrier as a result of UV irradiation as simulated by the model was found to be in good agreement with experimental data. (C) 1999 American Institute of Physics. [S0021-897 9(99)08802-7].