Potentiometric investigation of silicon electrode immersed in alkaline hydrogen peroxide solution containing trace level of iron

Sensing electrodes derived from the regular silicon wafer were shown to respond sensitively to the part-per-billion level of iron impurities in alkaline hydrogen peroxide solution (frequently referred to as standard clean-1 solution). The potentiometric results clearly indicate that the large positive shift of silicon open-circuit potential mainly originates from the adsorbed iron impurities on the surface oxide layer. Acid treatments by HCl or HF effectively regenerate the iron-contaminated silicon sensing electrode.