Passivation of Silicon Surface by Laser Rapid Heating

Abstract

We report rapid laser-induced passivation of the silicon surface. When the top surfaces of n-type 500-µm-thick silicon substrates with surfaces coated with 100 nm thermally grown SiO2 layers (initial samples) were irradiated with Ar plasma at 50 W for 120 s, the 635-nm-light induced minority carrier effective lifetime τeff decreased from 1.7x10 -3 (initial) to 1.7x10 -5 s because Ar plasma caused substantial carrier recombination defect states at the silicon surfaces. τeff was markedly increased to 1.7x10 -3 s by 940-nm-semiconductor laser irradiation at 3.57x10 4 W/cm 2 for 4 ms. Laser heating effectively decreased the density of plasma induced carrier recombination defect. However, laser heating of the initial sample at 4.0x10 4 W/cm 2 decreased τeff from 2.2x10 -3 (initial) to 1.7x10 -4 s. Additional laser heating at 3.70x10 4 W/cm 2 increased τeff to 3.9x10 -4 s and it partially cured laser in