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 10(15) cm-3 and 10(19) 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 x 10(18) 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.