Electrochemical Investigation of Si of Various Dopant Concentrations at Negative Overpotentials in Aqueous Electrolyte

n-Type and p-type Si samples of various doping concentrations (1014-1019 cm(-3)) are investigated in hydrogen fluoride electrolyte using voltammetry and electrochemical impedance spectroscopy (EIS) at negative overpotentials. In addition to the features of solution resistance, space charge, and double layer common to all the doped-Si samples, up to six different types of low-frequency (lf) features are observed in the EIS spectra, depending on the dopant and its concentration. These lf features corresponding to the sequential or simultaneous hydride formation and evolution processes are well resolved on Si of appropriate dopant concentration, unlike in the case of the widely investigated Pt and Pd. The results reported here with Si, a semiconducting material, lend experimental credence to the proposed theoretical models of hydrogen evolution reaction (HER), and the spectra are similar to the simulated spectra reported in the literature.

Automated summary

n-type and p-type Si samples with various doping concentrations were studied in hydrogen fluoride electrolyte, showing up to six different low-frequency features in EIS spectra at negative overpotentials. These features, related to hydride formation and evolution processes, were well resolved on Si of appropriate dopant concentration, lending experimental support to theoretical models of hydrogen evolution reaction.