13.56 MHz capacitance coupled Ar plasma irradiation at 50W for 120s caused serious damage at Si02/Si interfaces for n-type 500-pm-thick silicon substrates. The 635-nm-light induced minority carrier effective lifetime (led was decreased from 1.7 x 10(-3) (initial) to 1.0 x 10(-5) s by Ar plasma irradiation. Moreover, the capacitance response at 1 MHz alternative voltage as a function of the bias voltage (C-V) was changed to hysteresis characteristic associated with the density of charge injection type interface traps at the mid gap (D) at 9.1 x 10(11) cm(-2) eV(-1). Subsequent 940-nm laser annealing at 3.7 x 10(4)W/cm2 for 4.0 x 10(-3) s markedly increased leff to 1.7 x 10(-3) s and decreased Dit to 2.1 x 1010 cm(-2) eV(-1). The hysteresis phenomenon was reduced in C-Vcharacteristics. Laser annealing effectively decreased the density of plasma induced carrier recombination and trap states. However, laser annealing with a high power intensity of 4.0 x 10(4)W/cm(2) seriously caused a thermal damage associated with a low leff and a high Da with no hysteresis characteristic. (C) 2014 Elsevier B.V. All rights reserved.