MODELING OF THE TRANSIENT-BEHAVIOR OF ANODIC OXIDES FORMED IN SI HF ELECTROLYTE SYSTEMS/

In recent years, interest in semiconductor electrochemical electrodes has increased because of their possible uses in solar energy conversio n systems, integrated circuit technology, and many other applications. In this work, we have characterized a Si/fluoride electrolyte interfa ce. Measured transient flatband potential data were available. Startin g from these measurements, we have developed a model to calculate the charges inside the oxide layer formed at the Si/HF electrolyte interfa ce. In the first step, we assumed that the oxide charges decay due onl y to etching. The results obtained show a decreasing positive charge d istribution from the electrolyte side to the Si side. To show the effe ct of surface states on the charge distribution inside the oxide, a mo del in which we separated the oxide bulk charges from the fast electro nic surface states at the Si oxide interface was developed. We found t hat the surface states affect only the value of the charge distributio n at the very early phase of oxide etching. To confirm the validity of the model, we extended it to explain measured data for the variation of the transient electrochemical cell capacitance and current when the potential is stepped from an anodic value to a negative probe value. The results obtained are in good agreement with experiments.