Micro and nano-patterning of single-crystal diamond by swift heavy ion irradiation

© 2016 Elsevier B.V.This paper presents experimental data and analysis of the structural damage caused by swift-heavy ion irradiation of single-crystal diamond. The patterned buried structural damage is shown to generate, via swelling, a mirror-pattern on the sample surface, which remains largely damage-free. While extensive results are available for light ion implantations, this effect is reported here for the first time in the heavy ion regime, where a completely different range of input parameters (in terms of ion species, energy, stopping power, etc.) is available for customized irradiation. The chosen ion species are Au and Br, in the energy range 10–40 MeV. The observed patterns, as characterized by profilometry and atomic force microscopy, are reported in a series of model experiments, which show swelling patterns ranging from a few nm to above 200 nm. Moreover, a systematic phenomenological modeling is presented, in which surface swelling measurements are correlated to buried crystal damage. A comparison is made with data for light ion implantations, showing good compatibility with the proposed models. The modeling presented in this work can be useful for the design and realization of micropatterned surfaces in single crystal diamond, allowing generating highly customized structures by combining appropriately chosen irradiation parameters and masks.GG acknowledges support from the ALBA synchrotron, W. Schildkamp for inspiring discussions on the behaviour of diamond and J. Ferrer for his help in experiment preparation. GG, MD-H, VT-M, OP-R and JO acknowledge the projects MAT-2011-28379-C03-02 of the Spanish Ministry of Economy and Competitiveness, TECHNOFUSION(II)CM (S2013/MAE2745) of the Community of Madrid, and Moncloa Campus of International Excellence (UCM-UPM) foundation for offering a PICATA postdoctoral fellowship (OP-R). FP is supported by the “DiNaMo” project no. 157660 funded by National Institute of Nuclear Physics. PO is supported by the FIRB “Futuro in Ricerca 2010” project (CUP code: D11J11000450001) funded by MIUR and by the “A.Di.N-Tech.” project (CUP code: D15E13000130003) funded by the University of Torino and “Compagnia di San Paolo”. The MeV ion beam implantations performed at the INFN Legnaro National Laboratories was supported by the “Dia.Fab.” experiment, and those at the INFN LABEC Laboratory by the “FARE” and “CICAS” experiments. NMP is supported by the European Research Council (ERC StG Ideas 2011 BIHSNAM no. 279985, ERC PoC 2013-2 KNOTOUGH no. 632277 and ERC PoC 2015 SILKENE no. 693670), by the European Commission under the Graphene Flagship (“Nanocomposites”, no. 604391). FB acknowledges support from BIHSNAM. LL-M and CO acknowledge the Spanish MINECO through the Severo Ochoa Program (SEV-2015-0496) and MAT2013-47869-C4-1-P. CO acknowledges the specific agreement between ICMAB-CSIC and the Synchrotron Light Facility ALBA

Synergistic effects assessment between nuclear damage and electronic energy dissipation in LiTaO3 under heavy ion irradiation using optical waveguides properties and the irradiation angle of incidence

8 pags, 10 figs.High energy heavy ion irradiation has been performed in LiTaO in a broad set of experimental conditions to study the synergistic effects in the damage generation between the nuclear and the electronic energy loss mechanisms. Optical waveguides have been fabricated in LiTaO, using 20–25 MeV F and 40 MeV Si ions, and their refractive index profiles were used as a very accurate method for the in-depth damage profile determination and its correlation with the energy loss curves. In-situ optical reflectance of low energy irradiations (500 keV F and 300 keV Si ions) has been performed to estimate the nuclear damage kinetics of the buried regions of the high energy irradiations that are not optically accessible with the optical waveguide characterization in the fluence regime when the electronic damage is intense. The angle of incidence has been varied to enhance the damage and further ascertain the existence of a synergistic mechanism.his work has been supported by the Spanish Ministry of Economy and Competitiveness through the project MAT-2011-28379-C03-02, and by Madrid Community through the Program TECHNOFUSION(III)-CM (S2018/EMT-4437). We thank the Technical Staff of the CMAM-UAM center for their support with the irradiations

High-contrast slab waveguide fabrication in KY(WO4)2 by swift heavy ion irradiation

KY(WO4)2 and other materials of the double tungstate crystal family have been used for decades in active optical applications because of their relatively high refractive index (n2-2.04 @ 1550 nm), high transparency window (0.3-5 μm), excellent gain characteristics when doped with rare-earth ions and reasonably high thermal conductivity (∼3.3 Wm-1K-1). Low-contrast (Δn<0.02) on-chip amplifiers and lasers in this material with good performance have been shown in recent years. Higher refractive index contrast can further improve this performance, and allow easier integration with other integrated optics platforms due to their smaller footprint. Because double tungstate materials cannot be directly grown on many prospected substrates, other methods to fabricate optical waveguides with a thickness of 1-2 μm need to be investigated. In this work, swift heavy ion irradiation has been used to produce a planar waveguide by introducing a buried layer of lower refractive index in the KY(WO4)2 at a depth of ∼2.5 μm. After the irradiation, an annealing step was introduced to reduce the scattering losses. The refractive index profile, effective refractive indices and absorption spectra of the planar waveguides have been investigated for several annealing temperatures, and end-facet free-space coupling of 1550 nm has been used to measure the losses. For a fluence of 3·1014 ion/cm2 of 9 MeV C ions, propagation losses <1.5 dB/cm have been demonstrated at 1550 nm after an annealing step at 350°C

Structural damage on single-crystal diamond by swift heavy ion irradiation

4 págs.; 4 figs.© 2015 Elsevier B.V. © 2015 Elsevier B.V. All rights reserved. Experimental evidence of synthetic single-crystal diamond amorphization under the effect of irradiation with swift heavy ions is shown. The type of sharp thresholding behavior that characterizes electronic damage is not observed within a range of electronic stopping power covering up to 14 keV/nm. Amorphization is assessed by Rutherford Back Scattering Channeling (RBS-c) measurements done with light ions, after swift heavy ion irradiation. Results are analyzed and discussed in order to confirm the hypothesis of a nuclear damage-induced process, whereby it is concluded that electronic effects are not relevant in the studied range of stopping powers. The evolution of the amorphized fraction as a function of the irradiated fluence and nuclear stopping power is measured and discussed as well.We acknowledge funding from Spain's MINECO project: MAT-2011-28379-C03-02.Peer Reviewe

The genomic history of the Iberian Peninsula over the past 8000 years

Ancient DNA studies have begun to help us understand the genetic history and movements of people across the globe. Focusing on the Iberian Peninsula, Olalde et al. report genome-wide data from 271 ancient individuals from Iberia (see the Perspective by Vander Linden). The findings provide a comprehensive genetic time transect of the region. Linguistics analysis and genetic analysis of archaeological human remains dating from about 7000 years ago to the present elucidate the genetic impact of prehistoric and historic migrations from Europe and North Africa.Science, this issue p. 1230; see also p. 1153We assembled genome-wide data from 271 ancient Iberians, of whom 176 are from the largely unsampled period after 2000 BCE, thereby providing a high-resolution time transect of the Iberian Peninsula. We document high genetic substructure between northwestern and southeastern hunter-gatherers before the spread of farming. We reveal sporadic contacts between Iberia and North Africa by ~2500 BCE and, by ~2000 BCE, the replacement of 40% of Iberia’}s ancestry and nearly 100% of its Y-chromosomes by people with Steppe ancestry. We show that, in the Iron Age, Steppe ancestry had spread not only into Indo-European{–}speaking regions but also into non-Indo-European{–speaking ones, and we reveal that present-day Basques are best described as a typical Iron Age population without the admixture events that later affected the rest of Iberia. Additionally, we document how, beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean