Coupling effect of surface vibration and quantum confinement carriers in porous silicon

This paper deals with the structural characterization and the optical properties of deuterium terminated porous silicon (D-PS) fabricated by electrochemical anodization with DF-ethanol-D6 isotope electrolyte. Both the deuterium terminated and the usual hydrogen terminated porous silicons (H-PS) were characterized with transmission electron microscope analysis and Fourier transform infrared spectroscopy. These characterizations show that the nanometer crystalline structure of D-PS is almost the same as that of H-PS except for the surface termination. Although both PS show the same valence band energy shift, which was confirmed by X-ray photoemission spectroscopy, the photoluminescence spectrum of D-PS was different from that of H-PS. These results indicate that the surface vibration of terminated atoms couples to the excited energy states of quantum-confined carriers, which induces the surface-trapped states of Si nanocrystals.