Characterization of Changes in the Surface Properties of Silicon and Porous Silicon after Interaction with Hydroxyl Radicals
In this study we examined the changes on the surface properties of crystalline silicon (n -Si) and porous silicon (n-PS) as a function of exposition time to hydroxyl radicals generated by Fenton reaction and by means of the reaction between hydrogen peroxide electrochemically generated with iron (II) ions (electrofenton). Morphological, optical and wetting degree characterizations were performed for the evaluation of changes on the surface properties of these substrates. For morphological analysis, Atomic Force Microscope (AFM) was employed, evaluating pore size distribution on n-PS and y¡the influence of the exposition to FR. Changes in optical properties were analyzed by means of photoluminescence (PL) of n-PS exposed at OH radical at different periods and analyzing changes on the intensity of this signal. Finally, the wetting degree was analyzed by contact angles in two stages: (i) sessile drop method (ex- situ); (ii) captive bubble method (in- situ). The results obtained indicate a change in the silicon hydrophobicity/hydrophilicity as a function of exposition time to OH radicals. These changes have been associated with the dynamic surface transformation of silicon surface groups from Si - H (after cleaning treatment ) to Si - OH (after exposure to hydroxyl radical).