Electrochemical Study of the Interaction between Silicon n–type (100) and Hydroxyl Radicals

Semiconductor materials offer electronic properties that make them promising for being employed in the molecules detection in different environments. The present study proposes the analysis of changes in electrochemical responses of crystalline silicon (n–Si) after the interaction with hydroxyl radicals (•OH) in aqueous media.

In a first stage, the synthesis of hydroxyl radicals was done by means two procedures: (i) Fenton reaction and (ii) H2O2 photochemical decomposition using a UV digester for this purpose. Variables in these processes were time and hydrogen peroxide concentration in order to determine the dependence of these parameters on silicon–hydroxyl radical interaction.

After each immersion in radicals (separately both methods •OH of generation), it was performed a chemical cleaning treatment on silicon, which consisted: i) without further treatment; ii) HCl treatment or iii) HF treatment.  This last was done to avoid the presence of silicon oxide (SiO2) on the semiconductor surface. Subsequently, n–Si was placed in a three electrodes cell: silicon as working electrode, Ag / AgCl, KCl (saturated) as a reference electrode (0.197 V vs SHE) and a platinum counter electrode. After were registered the corresponding voltammograms  in a potassium chloride (KCl 0.1 M) solution at different pH values. In order to study the pH dependence on the interaction between substrate – reactive species (Si – •OH) were analyzed the current and the peak potential shift for each experimental conditions. Finally, Atomic Force Microscopy (AFM) was done to observe morphological changes in the substrate surface.