Increase in minority carrier lifetime measured by microwave irradiation method

We report increase in the minority carrier lifetime τ_eff by microwave irradiation using commercial microwave oven. N- and p-type crystalline silicon substrates coated with thermally grown SiO₂ layers were sandwiched by glass substrates and irradiated by microwave in a microwave oven at 700 W for 120 s. τ_eff increased from initial values of 1.8×10^-3 and 3.4×10^-4 s to 2.6×10^-3 and 8.4×10^-4 s for n- and p-type samples, respectively. The high values of τ_eff maintained for a long time above an one month. This method was applied to curing carrier recombination defects caused by Ar plasma irradiation. τ_eff decreased to 9.5×10^-6 and 2.6×10^-6 s by Ar plasma treatment at 50 W f or 60 s for n- and p-type samples. They were markedly increased to 1.8×10^-3 and 4.4×10^-4 s by microwave irradiation at 700 W for 120 s, respectively. They maintained above one month.