Thickness Dependence in Phase Formation and Properties of TaSe Layers Grown on GaP(111).

The effect of growth temperature and subsequent annealing on the epitaxy of both single- and few-layer TaSe on Se-terminated GaP(111) substrates is investigated. The selective growth of the 1T and 1H phases is shown up to 1 ML according to X-ray and ultraviolet photoelectron spectroscopies. The 1H monolayer, favored at low temperatures, exhibits a very homogeneous coverage after annealing, while the 1T ML, grown at high temperatures, is characterized by a better in-plane orientation.

High Capacitance Porous Ruthenium Nitride Films with High Rate Capability for Micro-Supercapacitors.

The demand for high-performance energy storage devices to power Internet of Things applications has driven intensive research on micro-supercapacitors (MSCs). In this study, RuN films made by magnetron sputtering as an efficient electrode material for MSCs are investigated. The sputtering parameters are carefully studied in order to maximize film porosity while maintaining high electrical conductivity, enabling a fast charging process.

Distinguishing cellular from abiotic spheroidal microstructures in the ca. 3.4 Ga Strelley Pool Formation.

The morphogenesis of most carbonaceous microstructures that resemble microfossils in Archean (4-2.5 Ga old) rocks remains debated. The associated carbonaceous matter may even-in some cases-derive from abiotic organic molecules.

3D LiMn O Thin Film Deposited by ALD: A Road toward High-Capacity Electrode for 3D Li-Ion Microbatteries.

Miniaturized electronics suffer from a lack of energy autonomy. In that context, the fabrication of lithium-ion solid-state microbatteries with high performance is mandatory for powering the next generation of portable electronic devices. Here, the fabrication of a thin film positive electrode for 3D Li-ion microbatteries made by the atomic layer deposition (ALD) method and in situ lithiation step is demonstrated.

In Situ Liquid Electrochemical TEM Investigation of LiMn Ni O Thin Film Cathode for Micro-Battery Applications.

Micro-batteries are attractive miniaturized energy devices for new Internet of Things applications, but the lack of understanding of their degradation process during cycling hinders improving their performance. Here focused ion beam (FIB)-lamella from LiMn Ni O (LMNO) thin-film cathode is in situ cycled in a liquid electrolyte inside an electrochemical transmission electron microscope (TEM) holder to analyze structural and morphology changes upon (de)lithiation processes. A high-quality electrical connection between the platinum (Pt) current collector of FIB-lamella and the microchip's Pt working electrode is established, as confirmed by local two-probe conductivity measurements.

Fast X-ray Nanotomography with Sub-10 nm Resolution as a Powerful Imaging Tool for Nanotechnology and Energy Storage Applications.

In the last decade, transmission X-ray microscopes (TXMs) have come into operation in most of the synchrotrons worldwide. They have proven to be outstanding tools for non-invasive ex and in situ 3D characterization of materials at the nanoscale across varying range of scientific applications. However, their spatial resolution has not improved in many years, while newly developed functional materials and microdevices with enhanced performances exhibit nanostructures always finer.

Engineering a Robust Flat Band in III-V Semiconductor Heterostructures.

Electron states in semiconductor materials can be modified by quantum confinement. Adding to semiconductor heterostructures the concept of lateral geometry offers the possibility to further tailor the electronic band structure with the creation of unique flat bands. Using block copolymer lithography, we describe the design, fabrication, and characterization of multiorbital bands in a honeycomb InGaAs/InP heterostructure quantum well with a lattice constant of 21 nm.

NanoSIMS Imaging of D/H Ratios on FIB Sections.

The D/H ratio imaging of weakly hydrated minerals prepared as focused ion beam (FIB) sections is developed in order to combine isotopic imaging by nanoscale secondary ion mass spectrometry (NanoSIMS) of micrometer-sized grains with other nanoscale imaging techniques, such as transmission electron microscopy. In order to maximize the accuracy, sensitivity, precision, and reproducibility of D/H ratios at the micrometer size, while minimizing the surface contamination at the same time, we explored all instrumental parameters known to influence the measurement of D/H ratios in situ. Optimal conditions were found to be obtained with the use of (i) a Cs ion source and detection of H and D at low mass resolving power, (ii) a primary beam intensity of 100 pA, and (iii) raster sizes in the range of 8-15 μm.

Size and shape control of a variety of metallic nanostructures using tilted, rotating evaporation and lithographic lift-off techniques.

Here, we demonstrate a simple top-down method for nanotechnology whereby electron beam (ebeam) lithography can be combined with tilted, rotated thermal evaporation to control the topography and size of an assortment of metallic objects at the nanometre scale. In order to do this, the evaporation tilt angle is varied between 1 and 24°. The technique allows the 3-dimensional tailoring of a range of metallic object shapes from sharp, flat bottomed spikes to hollow cylinders and rings-all of which have rotational symmetry and whose critical dimensions are much smaller than the lithographic feature size.

Trap-Free Heterostructure of PbS Nanoplatelets on InP(001) by Chemical Epitaxy.

Semiconductor nanocrystalline heterostructures can be produced by the immersion of semiconductor substrates into an aqueous precursor solution, but this approach usually leads to a high density of interfacial traps. In this work, we study the effect of a chemical passivation of the substrate prior to the nanocrystalline growth. PbS nanoplatelets grown on sulfur-treated InP (001) surfaces at temperatures as low as 95 °C exhibit abrupt crystalline interfaces that allow a direct and reproducible electron transfer to the InP substrate through the nanometer-thick nanoplatelets with scanning tunnelling spectroscopy.

Bottom-up fabrication of InAs-on-nothing MOSFET using selective area molecular beam epitaxy.

In this paper we report on the fabrication and electrical characterization of InAs-on-nothing metal-oxide-semiconductor field-effect transistor composed of a suspended InAs channel and raised InAs n+ contacts. This architecture is obtained using 3D selective and localized molecular beam epitaxy on a lattice mismatched InP substrate. The suspended InAs channel and InAs n+ contacts feature a reproducible and uniform shape with well-defined 3D sidewalls.

Morphology and valence band offset of GaSb quantum dots grown on GaP(001) and their evolution upon capping.

This work presents a detailed study of GaSb quantum dot (QD) epitaxy on (001) GaP substrates by means of molecular beam epitaxy. Despite the large mismatch between GaP and GaSb, we show that in the nucleation-diffusion regime, the QD size distribution follows the predictions of the scaling theory. Scanning transmission electron microscopy analysis of grown QDs reveal that they are plastically relaxed by 60° pairs of misfit dislocations and the valence band offset measured by x-ray photoelectron spectroscopy on such QDs amounts to 0.

3D silicon shapes through bulk nano structuration by focused ion beam implantation and wet etching.

The work presented in this paper concerns the synthesis of silicon (Si) 2D and 3D nanostructures using the delayed effect, caused by implanted Ga ions, on the dissolution of Si in aqueous solutions of tetramethylammonium hydroxide (TMAH). The crystalline silicon substrates (100) are first cleaned and then hydrogenated by immersion in an aqueous solution of hydrofluoric acid. The ion implantation is then carried out by a focused ion beam by varying the dose and the exposure time.

Iron minerals within specific microfossil morphospecies of the 1.88 Ga Gunflint Formation.

Problematic microfossils dominate the palaeontological record between the Great Oxidation Event 2.4 billion years ago (Ga) and the last Palaeoproterozoic iron formations, deposited 500-600 million years later. These fossils are often associated with iron-rich sedimentary rocks, but their affinities, metabolism, and, hence, their contributions to Earth surface oxidation and Fe deposition remain unknown.

Nonstoichiometric Low-Temperature Grown GaAs Nanowires.

The structural and electronic properties of nonstoichiometric low-temperature grown GaAs nanowire shells have been investigated with scanning tunneling microscopy and spectroscopy, pump-probe reflectivity, and cathodoluminescence measurements. The growth of nonstoichiometric GaAs shells is achieved through the formation of As antisite defects, and to a lower extent, after annealing, As precipitates. Because of the high density of atomic steps on the nanowire sidewalls, the Fermi level is pinned midgap, causing the ionization of the subsurface antisites and the formation of depleted regions around the As precipitates.

Quantitative impedance characterization of sub-10 nm scale capacitors and tunnel junctions with an interferometric scanning microwave microscope.

We present a method to characterize sub-10 nm capacitors and tunnel junctions by interferometric scanning microwave microscopy (iSMM) at 7.8 GHz. At such device scaling, the small water meniscus surrounding the iSMM tip should be reduced by proper tip tuning.

Novel heterostructured Ge nanowires based on polytype transformation.

We report on a strain-induced phase transformation in Ge nanowires under external shear stresses. The resulted polytype heterostructure may have great potential for photonics and thermoelectric applications. ⟨111⟩-oriented Ge nanowires with standard diamond structure (3C) undergo a phase transformation toward the hexagonal diamond phase referred as the 2H-allotrope.

Peptidic ligands to control the three-dimensional self-assembly of quantum rods in aqueous media.

The use of peptidic ligands is validated as a generic chemical platform allowing one to finely control the organization in solid phase of semiconductor nanorods originally dispersed in an aqueous media. An original method to generate, on a macroscopic scale and with the desired geometry, three-dimensional supracrystals composed of quantum rods is introduced. In a first step, nanorods are transferred in an aqueous phase thanks to the substitution of the original capping layer by peptidic ligands.

Vertical "III-V" V-shaped nanomembranes epitaxially grown on a patterned Si[001] substrate and their enhanced light scattering.

We report on a new form of III-V compound semiconductor nanostructures growing epitaxially as vertical V-shaped nanomembranes on Si(001) and study their light-scattering properties. Precise position control of the InAs nanostructures in regular arrays is demonstrated by bottom-up synthesis using molecular beam epitaxy in nanoscale apertures on a SiO(2) mask. The InAs V-shaped nanomembranes are found to originate from the two opposite facets of a rectangular pyramidal island nucleus and extend along two opposite <111> B directions, forming flat {110} walls.

Large array of sub-10-nm single-grain Au nanodots for use in nanotechnology.

A uniform array of single-grain Au nanodots, as small as 5-8 nm, can be formed on silicon using e-beam lithography. The as-fabricated nanodots are amorphous, and thermal annealing converts them to pure Au single crystals covered with a thin SiO(2) layer. These findings are based on physical measurements, such as atomic force microscopy (AFM), atomic-resolution scanning transmission electron microscopy, and chemical techniques using energy dispersive X-ray spectroscopy.

100 nm period grating by high-index phase-mask immersion lithography.

The interferogram of a high index phase mask of 200 nm period under normal incidence of a collimated beam at 244 nm wavelength with substantially suppressed zeroth order produces a 100 nm period grating in a resist film under immersion. The paper describes the phase mask design, its fabrication, the effect of electron-beam lithographic stitching errors and optical assessment of the fabricated sub-cutoff grating.

Impact features on Stardust: implications for comet 81P/Wild 2 dust.

Particles emanating from comet 81P/Wild 2 collided with the Stardust spacecraft at 6.1 kilometers per second, producing hypervelocity impact features on the collector surfaces that were returned to Earth. The morphologies of these surprisingly diverse features were created by particles varying from dense mineral grains to loosely bound, polymineralic aggregates ranging from tens of nanometers to hundreds of micrometers in size.

A nanofluidic emitter tip obtained by focused ion beam nanofabrication.

We report here the design, fabrication and testing of a novel nanofluidic device which we term a 'nano-nib' due to its resemblance to a nano-fountain pen. The nanofluidic device is an emitter tip which incorporates a nanofluidic capillary slot coupled to a microfluidic capillary slot. The microfluidic capillary slot is fabricated using reactive ion etching (RIE) whilst the nanofluidic capillary slot is fabricated using focused ion beam (FIB) etching.