Defect creation in mesoporous silicon irradiated with swift heavy ions
poster presentation: Monday 2010-08-23 05:00 PM - 07:00 PM in section Cluster ions, single ion, swift heavy ions, highly charged ions
Last modified: 2010-07-01
Abstract
Mesoporous silicon (PS) targets were processed by anodising p+ (r ≈ 0.01 W.cm) Si wafers in a Teflon etch cell, using a (1:1) HF-ethanol solution. Different current densities were used to obtain porosities between 40 and 80 %. The morphology of the PS layer was columnar with a typical crystallite size of 10 nm and its thickness was about 25 µm. The samples were irradiated at the GANIL accelerator, using 850 MeV 208Pb ions (SME beamline) or 100 MeV 131Xe ions (IRRSUD beamline). The fluences ranged from 1011 to 1013 cm-2. According to the SRIM2006 code the incident electronic stopping powers were Se = 11.2 keV.nm-1 and Se = 22.8 keV.nm-1 for xenon and lead projectiles, respectively. Raman spectroscopy and microscopy observations (TEM and SEM) were used to evidence radiation-induced disorder and structural modifications in both micrometer and nanometer scales. Before irradiation the characteristic Raman peak located at 520 cm-1 and ascribed to c-Si was evidenced. Electron diffraction patterns confirmed that the pristine PS layer is crystalline. After irradiation the Raman spectra exhibited an additional and clearly visible wide peak centred around 480 cm-1, which was ascribed to the a-Si phase. This feature was also confirmed by electron diffraction which evidenced the co-existence of crystalline and amorphous phases. From SEM observations the columnar morphology of the PS layer is not modified after irradiation. The fluence evolution of the amorphized fraction allowed to determine, for the different porosities used, a damage cross-section which was linked to the electronic stopping power of the projectile. The increased sensitivity of PS targets, compared to that of bulk Si, to irradiation in the electronic regime was interpreted in the framework of the thermal spike model.
Author(s) affiliation:
Pascal NEWBY*, Institut des Nanotechnologies de Lyon (INL), CNRS; INSA de Lyon, Villeurbanne F-69621, France
Vladimir LYSENKO, Institut des Nanotechnologies de Lyon (INL), CNRS; INSA de Lyon, Villeurbanne F-69621, France
Jean-Marie BLUET, Institut des Nanotechnologies de Lyon (INL), CNRS; INSA de Lyon, Villeurbanne F-69621, France
Olivier MARTY, Institut des Nanotechnologies de Lyon (INL), CNRS; Université Lyon 1, Villeurbanne F-69621,
Vincent AIMEZ, Department of Electrical Engineering, Université de Herbrooke, Sherbrooke, Québec, Canada, Canada
Luc FRECHETTE, Department of Mechanical Engineering, Université de Herbrooke, Sherbrooke, Québec, Canada, Canada
Isabelle MONNET, Centre de Recherche sur les Ions, les Matériaux et la photonique (CIMAP), CEA-CNRS, Université de Caen, France
*presenting author