CHARACTERIZATION STUDIES OF P-TYPE POROUS SI AND ITS PHOTOELECTROCHEMICAL ACTIVATION

Photoelectrochemical effects of surface modification with a porous layer have been studied experimentally in detail for p-type Si substrates. At first the in situ characterization of porous Si/electrolyte interfaces are carried out by impedance measurements in various electrolytes, as a function of the porous layer thickness. Information on the surface morphology and on the space charge layer capacitance can be separated by an appropriate adjustment of the bias voltage and frequency. An evidence of Fermi level pinning at the interface is found from an analysis of the flatband potential. Next, it is shown that deposition of Pt onto the porous Si layer (PSL) surface is useful for its photoelectrochemical activation. Effects of Pt are investigated by impedance and flatband potential measurements of the Pt-deposited PSL electrodes.