Analysis of capacitance-potential measurements at the silicon-electrolyte interface revisited

The analysis of the capacitance-potential curves is revisited by using a more accurate bias dependence of the silicon space charge layer capacitance (C_SC) under accumulation conditions (Tardella, A.; Chazalviel, J.-N. Phys. Rev. B 1985, 32, 2439). In the case of a well-defined stepped H-terminated Si(111) surface, we show that the improved analysis yields a more realistic C_H value: ∼8 μF/cm² (∼3.5 μF/cm² was derived from the Poisson-Boltzmann analysis). However, in the case of samples grafted with organic chains, we show that the model used for C _SC has no influence on the determination of the effective dielectric constant ∈_EFF of the organic layer.