title: Synthesis of colloidal solutions with silicon nanocrystals from porous silicon.
abstract: In this work, we have obtained colloidal solutions of Si nanocrystals (Si-ncs), starting from free-standing porous silicon (PSi) layers. PSi layers were synthesized using a two-electrode Teflon electrochemical cell; the etching solution contained hydrogen peroxide 30%, hydrofluoric acid 40% (HF), and methanol. The anodizing current density was varied to 250 mA cm(-2), 1 A cm(-2), and 1.2 A cm(-2). Thus obtained, PSi was mechanically pulverized in a mortar agate; then, the PSi powders were poured into different solutions to get the final Si-ncs colloidal solutions. The different optical, morphological, and structural characteristics of the colloidal solutions with Si-ncs were measured and studied. These Si-ncs colloidal solutions, measured by photoluminescence (PL), revealed efficient blue-green or violet emission intensities. The results of X-ray diffraction (XRD) indicate that the colloidal solutions are mainly composed of silicon nanocrystallites. The result of UV-vis transmittance indicates that the optical bandgap energies of the colloidal solutions varied from 2.3 to 3.5 eV for colloids prepared in methanol, ethanol, and acetone. The transmission electron microscopy (TEM) images showed the size of the nanocrystals in the colloidal solutions. Fourier transform infrared spectroscopy (FTIR) spectra showed different types of chemical bonds such as Si-O-Si, Si-CH2, and SiH x , as well as some kind of defects.
  61.46Df.-a; 61.43.Gt; 61.05.cp; 78.55.-m; 81.15.Gh.
authors.affiliation: Instituto de Ciencias, Centro de Investigaciones en Dispositivos Semiconductores, Benemérita Universidad Autónoma de Puebla, Ed. 103C o D, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla C.P. 72570, México.
authors.forename: José Alberto
authors.initials: JA
authors.lastname: Luna López
authors.affiliation: Instituto de Ciencias, Centro de Investigaciones en Dispositivos Semiconductores, Benemérita Universidad Autónoma de Puebla, Ed. 103C o D, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla C.P. 72570, México.
authors.forename: Abel
authors.initials: A
authors.lastname: Garzón Román
authors.affiliation: Instituto de Ciencias, Centro de Investigaciones en Dispositivos Semiconductores, Benemérita Universidad Autónoma de Puebla, Ed. 103C o D, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla C.P. 72570, México.
authors.forename: Estela
authors.initials: E
authors.lastname: Gómez Barojas
authors.affiliation: Instituto de Ciencias, Centro de Investigaciones en Dispositivos Semiconductores, Benemérita Universidad Autónoma de Puebla, Ed. 103C o D, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla C.P. 72570, México.
authors.forename: Jf Flores
authors.initials: JF
authors.lastname: Gracia
authors.affiliation: Instituto de Ciencias, Centro de Investigaciones en Dispositivos Semiconductores, Benemérita Universidad Autónoma de Puebla, Ed. 103C o D, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla C.P. 72570, México.
authors.forename: Javier
authors.initials: J
authors.lastname: Martínez Juárez
authors.affiliation: Instituto de Ciencias, Centro de Investigaciones en Dispositivos Semiconductores, Benemérita Universidad Autónoma de Puebla, Ed. 103C o D, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla C.P. 72570, México.
authors.forename: Jesús
authors.initials: J
authors.lastname: Carrillo López
keywords: Colloidal solution; FTIR; PL; Silicon nanocrystal; XRD