Minority carrier lifetime measurements by multiple wavelength light induced carrier microwave absorption method

We report the minority carrier effective lifetime τ_eff of crystalline silicon substrate via microwave absorption caused by free carriers induced by multiple wavelength light illumination at 635 and 980 nm. τ_eff was low of about 2.5×10^-6 s in the case of 635 nm light illumination for n-type 520 μm thick bare silicon substrate, while it was high ranged from 8.2 × 10^-6 to 1.8 × 10^-5 s in the case of 980 nm light illumination because carrier recombination defect sites concentrated at the surface region and a diffusion time about 10^-5 s was necessary for minority carriers generated by 980 nm light to reach the surface because of the light penetration depth of 125 μm. This method determined that Ar plasma induced carrier recombination defect sites located at the silicon surface.