Surface recombination velocity of highly doped n-type silicon

Abstract
New experimental data for the minority‐carrier surface recombination velocity of n‐type silicon, Sp, are reported. The data, obtained from photoconductance decay measurements of the recombination currents corresponding to different phosphorus diffusions, include oxide‐passivated, unpassivated and metal‐coated surfaces. For the passivated case, Sp increases linearly with surface dopant density, ND, for dopant densities higher than 1×1018 cm−3, while for unpassivated (bare) and for metal‐coated silicon Sp remains essentially constant, at about 2×105 cm/s and 3×106 cm/s, respectively. The experiments also allow for a determination of the apparent energy bandgap narrowing as a function of dopant density, ΔEgapp=14 meV [ln(ND/1.4×1017 cm−3)]. These surface recombination velocity and ΔEgapp data form, together with the dependences of minority‐carrier lifetime, τp, and mobility, μp, used in the analysis, a consistent set of parameters that fully characterize highly doped n‐type silicon.