Microscopic, self-oscillating domains at the silicon surface during its anodic dissolution in a fluoride electrolyte

During the anodic dissolution of silicon in fluoride electrolytes, for a given potential E ≥ 3 V_sce, any variation of the electrode potential (even very small) makes the current undergo damped oscillations. Correspondingly, the admittance of the interface exhibits resonances at the same frequency and at its overtones. This resonant behavior is well understood in the framework of a macroscopic model, based upon the picture of a heterogeneous surface, partitioned into small, independent, self-oscillating domains. Noise measurements, which give access to the typical size of these domains, have been performed and give a typical dimension for the domains of the order of 1000 Å.