Modulation of Flat-band Potential and Increase in Photovoltage for n-Si Electrodes by Formation of Halogen Atom Terminated Surface Bonds

Abstract

Abstract The flat-band potential (UFB) of n-Si electrodes in concentrated hydrogen halide (HX) solutions, as determined from Mott-Schottky plots and the onset potential of photocurrent, shifts largely toward the negative with the decreasing electronegativity of halogen atoms. XPS studies have shown the presence of halogen atoms on the Si electrodes which were beforehand immersed in the HX solutions. The shift in UFB can be explained as due to changes in surface potential by formation of Si-halogen surface termination bonds.