X-RAY PHOTOELECTRON SPECTROSCOPIC STUDIES OF THE CHEMICAL NATURE OF AS-PREPARED AND NAOH-TREATED POROUS SILICON LAYER

The effect of various surface treatments of a porous silicon layer (PSL) including etching in NaOH solution on the chemical nature of the surface was studied using x-ray photoelectron spectroscopy. As-prepared PSL, which is formed by anodic oxidation of silicon in ethanolic HF solution, is covered with silicon oxide. NaOH treatment removes the surface oxide almost completely. Chemical states of surface silicon at the NaOH-treated PSL surface are very close to that at the HF-treated silicon surface. Surface oxygen on the NaOH-treated PSL surface seems to be in the form of Si-OH.