Electron-paramagnetic-resonance study of the microscopic structure of the Si(001)- SiO 2 interface

International audienc

Interaction of very low energy electron beams with micro porous silicon substrates: ESD studies of H

This paper deals with the study of very low incident energy (0–12 eV) electron beam interactions with porous silicon (PS) substrates. It mainly concerns electron stimulated desorption (ESD) of negative H− ions ejected during a resonant bond breaking process. The experiments performed with a specific experimental set-up show that initially the PS surface was repulsive with regards to the low energy electron beam so that a reference voltage v0 = 2.44 V sets the origin of incident electron energy. Thus the resonant desorption process was centred at 7.5 eV with a threshold at 4.6 eV, close to characterisations on the hydrogenated surfaces of silicon crystals. However, the desorption yield was here very low in comparison. It was assumed that a large fraction of the incident electron beam entered the substrate depth enough without triggering significant ion desorption. Progressive shifts in the reference potentials up v0 = 5 V and significant reductions in desorption yield were caused by repeated electron bombardments with energies never exceeding 12 eV. These variations were attributed to changes in the surface composition of the porous silicon. It is assumed that residual fluorine atoms left after PS preparation might migrate towards the porous silicon surface as F− ions to enhance the electron beam repulsion. Following a general discussion, several experiments are suggested in order better to control modification of surface composition responsible for the ageing of the PS substrates

Structural and magnetic properties of Co-doped ZnO thin films grown by ultrasonic spray pyrolysis method

International audienceCobalt-doped ZnO thin films with several different percentage of Co from 0 up to 15 at% were synthesized via a cheap, simple and versatile method i.e. ultrasonic spray pyrolysis at atmospheric pressure and a substrate temperature of 350 degrees C. The structure of the as prepared samples was characterized by X-ray diffraction (XRD), Raman spectroscopy and FTIR. The Co-doping effect is revealed by the presence of three additional peaks around 235, 470 and 538 cm(-1) respect to the Raman spectra of the unsubstituted film. Fourier transform infrared spectroscopy (FTIR) put in evidence the decrease of the bond force constant f with increasing Co-doping. By ultra-violet visible near infrared (UV-Vis-NIR) spectroscopy on Co-doped samples it was possible to show the presence of additional absorption bands at approximately 570, 620 and 660 nm suggesting that Co2+ ions do not change their oxidation when substituted to zinc and the ZnO lattice does not change its wurtzite structure as well. Finally, all our samples exhibit a paramagnetic behavior without any trace of intrinsic room temperature ferromagnetism. (C) 2016 Elsevier Ltd. All rights reserved

Abstracts of 1st International Conference on Computational & Applied Physics

This book contains the abstracts of the papers presented at the International Conference on Computational & Applied Physics (ICCAP’2021) Organized by the Surfaces, Interfaces and Thin Films Laboratory (LASICOM), Department of Physics, Faculty of Science, University Saad Dahleb Blida 1, Algeria, held on 26–28 September 2021. The Conference had a variety of Plenary Lectures, Oral sessions, and E-Poster Presentations. Conference Title: 1st International Conference on Computational & Applied PhysicsConference Acronym: ICCAP’2021Conference Date: 26–28 September 2021Conference Location: Online (Virtual Conference)Conference Organizer: Surfaces, Interfaces, and Thin Films Laboratory (LASICOM), Department of Physics, Faculty of Science, University Saad Dahleb Blida 1, Algeria