Minority Carrier Annihilation Property for Crystalline Silicon Surfaces

We report minority carrier recombination effect at cut edges for 520 mu m thick p- and n-type silicon substrates coated with thermally grown SiO2 layers. Samples were mechanically cut to make bare silicon surface edges keeping with other area coated with thermally grown SiO2. We demonstrate precisely spatial change in minority carrier effective lifetime tau(eff) around the cutting edges. 9.35 GHz microwave transmittance measurement system with 635 nm light illumination were used to precisely measure spatial distribution the minority carrier lifetime tau(eff) across the cut edges. tau(eff) decreased from 3.0x10(-4) and 3.4x10(-3) s (initial) to 4.0x10(-5) and 6.5x10(-4) s at cut edges for p- and n-type samples, respectively. Moreover, decrease in was observed in regions 9 and 8 mm apart from the cut edges for p- and n-type samples, respectively. Those distances were much larger than the minority carrier effective diffusion length. This paper demonstrates and discuss serious carrier annihilation effect caused by the cut edges.