On effective surface recombination parameters

This paper examines two effective surface recombination parameters: the effective surface recombination velocity S-eff and the surface saturation current density J(0s). The dependence of S-eff and J(0s) on surface charge Q, surface dopant concentration N-s, and interface parameters is derived. It is shown that for crystalline silicon at 300K in low-injection, S-eff is independent of N-s only when Q(2)/N-s< 1900 cm in accumulation and Q(2)/N-s< 1600 cm in depletion; otherwise S-eff increases with N-s. These conditions are rarely satisfied in undiffused wafers but sometimes satisfied in heavily diffused wafers when coated with lowly charged films. Under the same conditions, J(0s) is independent of N-s when Q(2)/N-s > 1.5 x 10(7) cm for accumulation and Q(1.85)/N-s > 1.5 x 10(6) cm for inversion. These conditions are commonly satisfied in undiffused wafers but rarely in diffused wafers. We conclude that for undiffused silicon, J(0s) is superior to the conventional S-eff as a metric for quantifying the surface passivation, whereas for diffused silicon, the merit in using J(0s) or S-eff (or neither) depends on the sample. Experimental examples are given that illustrate the merits and flaws of J(0s) and S-eff. (C) 2014 AIP Publishing LLC.