IN-SITU IMPEDANCE SPECTROSCOPY OF SILICON ELECTRODES DURING THE FIRSTSTAGES OF POROUS SILICON FORMATION

Time-resolved in situ electrochemical impedance spectroscopy measureme nts were performed in HF-electrolyte during the initial stages of nano - and mesoporous layer formation on p-Si and p(+)-Si electrodes respec tively. A simple electrical equivalent circuit which involves a consta nt phase element to account for the distributed nature of the interfac ial capacitance was chosen to model the impedance behaviour of the Si electrode. The experimental impedance spectra obtained were subjected to data validation and were then used to estimate the circuit paramete rs. Their time dependence is discussed in terms of the porous silicon growth mechanism. (C) 1997 Elsevier Science S.A.