Electrochemical impedance characterization of transient effects in anodic oxidation of silicon

The work shows the possibilities of the application of electrochemical impe dance and open-circuit measurements in studies of electrochemical anodizati on processes on silicon and post-anodizing treatments of anodized layers. I t is shown that these methods are very sensitive to dynamic processes accom panying the formation of porous silicon layers and porous silicon oxides. P articularly, different stages of the oscillatory kinetics of the anodic oxi de growth on silicon have been studied and details of the oxide morphology have been revealed. It is shown for example, that essential changes of the conditions at electrolyte/sample interface occur in the vicinity of the cha racteristic points of the oscillatory kinetics revealed as sharp changes of the ac impedance characteristics. Ageing phenomena in porous silicon and p orous silicon oxide have also been monitored using Electrochemical Impedanc e Spectroscopy (EIS) and Open Circuit Potential (OCP) methods and some assu mptions causing the ageing of the layers have been put forward.