Assessment and parameterisation of Coulomb-enhanced Auger recombination coefficients in lowly injected crystalline silicon

In traditional band-to-band Auger recombination theory, the low-injection carrier lifetime is an inverse quadratic function of the doping density. However, for doping densities below about 3×1018 cm−3, the low-injection Auger lifetimes measured in the past on silicon were significantly smaller than predicted by this theory. Recently, a new theory has been developed A. Hangleiter and R. Häcker, Phys. Rev. Lett. 65, 215 (1990) that attributes these deviations to Coulombic interactions between mobile charge carriers. This theory has been supported experimentally to a high degree of accuracy in n-type silicon; however, no satisfactory support for it has been found in p-type silicon for doping densities below 3×1017 cm−3. In this work, we investigate the most recent lifetime measurements of crystalline silicon and support experimentally the Coulomb-enhanced Auger theory in p-type silicon in the doping range down to 1×1016 cm−3. Based on the experimental data, we present an empirical parameterisation of the low-injection Auger lifetime. This parameterisation is valid in n- and p-type silicon with arbitrary doping concentrations and for temperatures between 70 and 400 K. We implement this parameterisation into a numerical device simulator to demonstrate how the new Auger limit influences the open-circuit voltage capability of silicon solar cells. Further, we briefly discuss why the Auger recombination rates are less enhanced under high-injection conditions than under low-injection conditions.