Focussed Ion Beam (FIB) milling is a mainstay of nano-scale machining. By manipulating a tightly focussed beam of energetic ions, often gallium (Ga+), FIB can sculpt nanostructures via localised sputtering. This ability to cut solid matter on the nano-scale has revolutionised sample preparation across the life-, earth- and materials sciences. For example FIB is central to microchip prototyping, 3D material analysis, targeted electron microscopy sample extraction and the nanotechnology behind size-dependent material properties. Despite its widespread usage, detailed understanding of the functional consequences of FIB-induced structural damage, intrinsic to the technique, remains elusive. Here, we present nano-scale measurements of three-dimensional, FIB-induced lattice strains, probed using Bragg Coherent X-ray Diffraction Imaging (BCDI). We observe that even low gallium ion doses, typical of FIB imaging, cause substantial lattice distortions. At higher doses, extended self-organised defect structures appear, giving rise to stresses far in excess of the bulk yield limit. Combined with detailed numerical calculations, these observations provide fundamental insight into the nature of the damage created and the structural instabilities that lead to a surprisingly inhomogeneous morphology.
Tungsten is the main candidate material for plasma-facing armour components in future fusion reactors. Bombardment with energetic fusion neutrons causes collision cascade damage and defect formation. Interaction of defects with helium, produced by transmutation and injected from the plasma, modifies defect retention and behaviour. Here we investigate the residual lattice strains caused by different doses of helium-ion-implantation into tungsten and tungsten-rhenium alloys. Energy and depth-resolved synchrotron X-ray micro-diffraction uniquely permits the measurement of lattice strain with sub-…
Helium implantation in epitaxial thin films is a way to control the out-of-plane deformation independently from the in-plane strain controlled by epitaxy. In particular, implantation by means of a helium microscope allows for local implantation and patterning down to the nanometer resolution, which is of interest for device applications. We present here a study of bismuth ferrite (BiFeO3) films where strain was patterned locally by helium implantation. Our combined Raman, XRD and TEM study shows that the implantation causes an elongation of the BiFeO3 unit cell and ultimately a transition towa…
Manipulating the strain induced poly-domains and phase transition in correlated oxide material are important for high performance devices fabrication. Though the electronic transport in the strained oxide film at macroscopic scales can be directly measured, the anisotropic electronic state and the controllable phase separation cross the insulator-to-metal transition within nanoscale size are still elusive. Here, we selected VO2 crystal film as a prototypical oxide and achieved the manipulation of anisotropy electronic phase separation via injecting He+ nanobeam into VO2 film at room temperatur…
We report on the use of helium ion implantation to independently control the out-of-plane lattice constant in epitaxial La0.7Sr0.3MnO3 thin films without changing the in-plane lattice constants. The process is reversible by a vacuum anneal. Resistance and magnetization measurements show that even a small increase in the out-of-plane lattice constant of less than 1% can shift the metal-insulator transition and Curie temperatures by more than 100 °C. Unlike conventional epitaxy-based strain tuning methods which are constrained not only by the Poisson effect but by the limited set of available su…
Ge-Sn alloys with a sufficiently high concentration of Sn is a direct bandgap group IV material. Recently, ion implantation followed by pulsed laser melting has been shown to be a promising method to realize this material due to its high reproducibility and precursor-free process. A Ge-Sn alloy with ~9 at.% Sn was shown to be feasible by this technique. However, the compressive strain, inherently occurring in heterogeneous epitaxy of the film, evidently delays the material from the direct bandgap transition. In this report, an attempt to synthesize a highly-relaxed Ge-Sn alloy will be presente…
Understanding the anisotropic response of $β$-Ga$_2$O$_3$ to ion implantation
INESC Microsystems and Nanotechnology（微电子与纳米技术研究所）；Institute for Plasmas and Nuclear Fusion, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院等离子体与核聚变研究所）；Department of Physics, University of Helsinki（赫尔辛基大学物理系）；Department of Nuclear Science and Engineering, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院核科学与工程系）；Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf（德累斯顿罗斯多夫亥姆霍兹中心离子束物理与材料研究所）；Centre for Nuclear Sciences and Technologies, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院核科学与技术中心）；i3N, Department of Physics, University of Aveiro（阿威罗大学物理系纳米科学研究所）
Raman spectroscopy has been used to identify defective bonding in neon and silicon ion irradiated single crystals of 6H-SiC. Observable differences exist in the C-C bonding region corresponding to different defect structures for neon and silicon ion implantations. Raman spectra of ion irradiated SiC show less tensile strain than neutron irradiations, explained by a residual compressive stress caused by the swelling constrained by the undamaged substrate. Evidence of oxidation during high temperature ion implantation is observed as C-O and Si-O Raman signals. Annealing irradiated SiC while acqu…
Formation of Ag and Au Plasmonic Nanoparticles by Ion Implantation in Ga$_2$O$_3$ thin films
INESC Microsystems and Nanotechnology（微电子与纳米技术研究所）；Institute for Plasmas and Nuclear Fusion, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院等离子体与核聚变研究所）；Université Caen Normandie, CEA, ENSICAEN, CNRS, Normandie Univ, CIMAP UMR6252（卡昂诺曼底大学）；Centre for Nuclear Sciences and Technologies, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院核科学与技术中心）；Department of Nuclear Science and Engineering, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院核科学与工程系）
Au and Ag nanoparticles produced by ion implantation in single-crystalline $β$-Ga$_2$O$_3$
INESC Microsystems and Nanotechnology（INESC微系统和纳米技术研究所）；Institute for Plasmas and Nuclear Fusion, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院等离子体与核聚变研究所）；Centre for Nuclear Sciences and Technologies, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院核科学与技术中心）；Department of Nuclear Science and Engineering, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院核科学与工程系）
Magneto-ionic control of magnetic properties through ionic migration has shown promise in enabling new functionalities in energy-efficient spintronic devices. In this work, we demonstrate the effect of helium ion irradiation and oxygen implantation on magneto-ionically induced exchange bias effect in Gd/Ni$_{0.33}$Co$_{0.67}$O heterostructures. Irradiation using $He^+$ leads to an expansion of the Ni$_{0.33}$Co$_{0.67}$O lattice due to strain relaxation. At low He+ fluence ($\leq$ 2$\times$10$^{14}$ ions cm$^{-2}$), the redox-induced interfacial magnetic moment initially increases, owing to en…
Developing a comprehensive understanding of the modification of material properties by neutron irradiation is important for the design of future fission and fusion power reactors. Self-ion implantation is commonly used to mimic neutron irradiation damage, however an interesting question concerns the effect of ion energy on the resulting damage structures. The reduction in the thickness of the implanted layer as the implantation energy is reduced results in the significant quandary: Does one attempt to match the primary knock-on atom energy produced during neutron irradiation or implant at a mu…
The paper reports fabrication of Germanium-on-Insulator (GeOI) wafer by Oxygen ion implantation of an undoped single crystalline Ge wafer of orientation (100). Oxygen ions of energy 200 keV were implanted. The implanted wafer was subjected to Rapid Thermal Annealing to 650 C. The resulting wafer has a top crystalline Ge layer of 220 nm thickness and Buried Oxide layer (BOX) layer of good quality crystalline Germanium oxide with thickness around 0.62 micron. The crystalline BOX layer has hexagonal crystal structure with lattice constants close to the standard values. Raman Spectroscopy, cross-s…
Anisotropic implantation damage build-up and crystal recovery in $β$-Ga$_2$O$_3$
INESC Microsystems and Nanotechnology（微电子学与纳米技术研究所）；Institute for Plasmas and Nuclear Fusion, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院等离子体与核聚变研究所）；Department of Nuclear Science and Engineering, Instituto Superior Técnico, University of Lisbon（里斯本大学高等理工学院核科学与工程系）；Centro de Ciências e Tecnologias Nucleares, University of Lisbon（里斯本大学核科学与技术中心）
The development of color centers in diamond as the basis for emerging quantum technologies has been limited by the need for ion implantation to create the appropriate defects. We present a versatile method to dope diamond without ion implantation, by synthesis of a doped amorphous carbon precursor and transformation at high temperatures and high pressures. To explore this bottom-up method for color center generation, we rationally create silicon-vacancy defects in nanodiamond and investigate them for optical pressure metrology. In addition, we show that this process can generate noble gas defe…
A method for obtaining a smooth, single crystal diamond surface is presented, whereby a sacrificial defective layer is created by implantation and graphitized by annealing before being selectively etched. We have used O+ at 240 keV, the main process variables being the ion fluence (ranging from 3x10^15 cm^-2 to 3x10^17 cm^-2) and the final etching process (wet etch, H2 plasma and annealing in air). The substrates were characterized by atomic force microscopy, optical profilometry and white beam X-ray topography. The influence of the various process parameters on the resulting lift-off efficien…
Nanoparticles are ubiquitous in nature and are increasingly important for technology. They are subject to bombardment by ionizing radiation in a diverse range of environments. In particular, nanodiamonds represent a variety of nanoparticles of significant fundamental and applied interest. Here we present a combined experimental and computational study of the behaviour of nanodiamonds under irradiation by xenon ions. Unexpectedly, we observed a pronounced size effect on the radiation resistance of the nanodiamonds: particles larger than 8 nm behave similarly to macroscopic diamond (i.e. charact…
Doping of substrates at desired locations is a key technology for spin-based quantum memory devices. Focused ion beam implantation is well-suited for this task due to its high spacial resolution. In this work, we investigate ion-beam implanted erbium ensembles in Yttrium Orthosilicate crystals by means of confocal photoluminescence spectroscopy. The sample temperature and the post-implantation annealing step strongly reverberate in the properties of the implanted ions. We find that hot implantation leads to a higher activation rate of the ions. At high enough fluences, the relation between the…
We present experimental results and numerical simulations to investigate the modification of structural-mechanical properties of ion-implanted single-crystal diamond. A phenomenological model is used to derive an analytical expression for the variation of mass density and elastic properties as a function of damage density in the crystal. These relations are applied together with SRIM Monte Carlo simulations to set up Finite Element simulations for the determination of internal strains and surface deformation of MeV-ion-implanted diamond samples. The results are validated through comparison wit…
We report persistently increased conduction in ZnO nanowires irradiated by ion beam with various ion energies and species. This effect is shown to be related to the already known persistent photo conduction in ZnO and dubbed persistent ion beam induced conduction. Both effects show similar excitation efficiency, decay rates, and chemical sensitivity. Persistent ion beam induced conduction will potentially allow countable (i.e., single dopant) implantation in ZnO nanostructures and other materials showing persistent photo conduction.
The local variation in inter-atomic distances, or local lattice strain often influences significantly material properties of nanoparticles. Strain measurement with ~1% precision is provided by recent atomic-resolution electron microscopy. However, the precision has been limited by noises in the experimental data. Here, we have applied one of the data-driven analyses, Gaussian process regression to predict true form of strain. The precision has been improved to be sub-percent of 0.2 % and more for detection of local strain. Rod-shaped nanoparticles have been revealed to contain characteristic l…
The article presents a mapping of the residual strain along the axis of InAs/InSb heterostructured nanowires. Using confocal Raman measurements, we observe a gradual shift in the TO phonon mode along the axis of these nanowires. We attribute the observed TO phonon shift to a residual strain arising from the InAs/InSb lattice mismatch. We find that the strain is maximum at the interface and then monotonically relaxes towards the tip of the nanowires. We also analyze the crystal structure of the InSb segment through selected area electron diffraction measurements and electron diffraction tomogra…
In the present work, we demonstrate for the first time the outstanding dynamic mechanical properties of nano-quasicrystalline Al93Fe3Cr2Ti2 at.% alloy and composites. Unlike most crystalline aluminium-based alloys, this alloy and composites exhibit substantial strain rate sensitivity and retain much of their ductility at high rates of strain. This opens new pathways for use in safety-critical materials where impact resistance is required.
Group-IV color centers in diamond have garnered great interest for their potential as optically active solid-state spin qubits. Future utilization of such emitters requires the development of precise site-controlled emitter generation techniques that are compatible with high-quality nanophotonic devices. This task is more challenging for color centers with large group-IV impurity atoms, which are otherwise promising because of their predicted long spin coherence times without a dilution refrigerator. For example, when applied to the negatively charged tin-vacancy (SnV$^-$) center, conventional…
Nanoindentation is a widely used method for sensitive exploration of the mechanical properties of micromechanical systems. We derived an empirical analysis technique to extract stress-strain field gradient and divergence representations from nanoindentation measurements. With this approach local gradients and heterogeneities can be discovered to obtain more detail about the sample's microstructure, thus enhancing the analytic capacity of the nanoindentation technique. We analysed nanoindentation tests of bulk solid substrates, namely bearing and tooling steel, and fused silica. Oscillations of…
We investigate the crystal properties of CdTe nanowires overgrown with HgTe. Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) confirm, that the growth results in a high ensemble uniformity and that the individual heterostructures are single-crystalline, respectively. We use high-resolution X-ray diffraction (HRXRD) to investigate strain, caused by the small lattice mismatch between the two materials. We find that both CdTe and HgTe show changes in lattice constant compared to the respective bulk lattice constants. The measurements reveal a complex strain …
Efficient creation of shallow NV$^-$ ensembles by high-angle ion implantation
The University of Tokyo（东京大学）；National Institute of Advanced Industrial Science and Technology（国立产业技术综合研究所）；National Institute for Materials Science（国立材料研究所）
Using first-principles computations, we study the effect of epitaxial strains on electronic structure variations across ZnSe/ZnTe nano-heterostructures. Epitaxial strains of various types are modeled using pseudomorphic ZnSe/ZnTe heterostructures. We find that a wide range of band gaps (spanning the visible solar spectrum) and band offsets (0-1.5 eV) is accessible across the heterostructures in a controllable manner via reasonable levels of epitaxial strain. In addition to quantum confinement effects, strain in ZnSe/ZnTe heterostructures may thus be viewed as a powerful degree of freedom that …
Strain engineering enables the direct modification of the atomic bonding and is currently an active area of research aimed at improving the electrocatalytic activity. However, directly measuring the lattice strain of individual catalyst nanoparticles is challenging, especially at the scale of a single unit cell. Here, we quantitatively map the strain present in rhodium@platinum (core@shell) nanocube electrocatalysts using conventional aberration-corrected scanning transmission electron microscopy (STEM) and the recently developed technique of 4D-STEM nanobeam electron diffraction. We demonstra…
Reconfigurable Strain Gradient Polarity in Crystalline Oxide Nanomembranes for Controlled Bending of Functional Materials
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory（斯坦福材料能源科学研究所，SLAC国家加速器实验室）；Department of Applied Physics, Stanford University（斯坦福大学应用物理系）；Department of Physics, Stanford University（斯坦福大学物理系）
We investigate monocrystalline InAs nanowires (NWs) which are grown by molecular beam epitaxy (MBE) and induced by focused ion beam (FIB) implanted Au spots. With this unique combination of methods an increase of the aspect ratio, i.e. the length to width ratio, of the grown NWs up to 300 was achieved. To control the morphology and crystalline structure of the NWs, the growth parameters like temperature, flux ratios and implantation fluence are varied and optimized. Furthermore, the influence of the used molecular arsenic species, in particular the As$_2$ to As$_4$ ratio, is investigated and a…
