Bistability in the surface dipole of silicon grafted with copper nanoparticles: An in-situ electrochemical MIR-FTIR study

Bistable (hysteretic) behavior was observed in the current vs. potential relationship of p-type silicon grafted with copper nanoparticles in hydrofluoric acid. In-situ multiple-internal-reflectance FTIR spectroscopy indicated that the silicon surface is hydroxyl- (SiOH) or partially fluorine-terminated (SiF) in response to the bistability. It is considered that autocatalytic chemical reactions in which the shift of flat-band potential of silicon coupled with the change of the surface termination plays a key role in the observed bistability.

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► Open circuit potential of nano-Cu grafted Si exhibited bistability in HF solution.
► The Si surface was analyzed by in-situ MIR-FTIR technique.
► It was shown that Si surface was terminated either by OH or F in the bistable region.
► Oscillation in the open circuit potential can appear in the bistable region.