Intrinsic upper limits of the carrier lifetime in silicon

We have measured the carrier lifetime in ultrapure n- and p-type silicon with carrier densities between 1015 cm−3 and 1019 cm−3. At high carrier densities the dominant recombination mechanism is known to be band-to-band Auger recombination. At carrier densities below some 5×1018 cm−3 experimentally determined carrier lifetimes in n- and p-type silicon were always found to be smaller than expected for band-to-band Auger recombination. Our results are explained by taking into account electron–hole correlations in the Auger process. Since Auger recombination is an unavoidable material property this represents a new intrinsic upper limit of the carrier lifetime in silicon.