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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Fracture Tests of Etched Components Using a Focused Ion Beam Machine

Many optical MEMS device designs involve large arrays of thin (0.5 to 1 micron components subjected to high stresses due to cyclic loading. These devices are fabricated from a variety of materials, and the properties strongly depend on size and processing. Our objective is to develop standard and convenient test methods that can be used to measure the properties of large numbers of witness samples, for every device we build. In this work we explore a variety of fracture test configurations for 0.5 micron thick silicon nitride membranes machined using the Reactive Ion Etching (RIE) process. Testing was completed using an FEI 620 dual focused ion beam milling machine. Static loads were applied using a probe. and dynamic loads were applied through a piezo-electric stack mounted at the base of the probe. Results from the tests are presented and compared, and application for predicting fracture probability of large arrays of devices are considered.

Kuhn, Jonathan, L.↗
NASA NTRS1998

Nanoscale Etching and Indentation of Silicon Surfaces with Carbon Nanotubes

The possibility of nanolithography of silicon and germanium surfaces with bare carbon nanotube tips of scanning probe microscopy devices is considered with large scale classical molecular dynamics (MD) simulations employing Tersoff's reactive many-body potential for heteroatomic C/Si/Ge system. Lithography plays a key role in semiconductor manufacturing, and it is expected that future molecular and quantum electronic devices will be fabricated with nanolithographic and nanodeposition techniques. Carbon nanotubes, rolled up sheets of graphene made of carbon, are excellent candidates for use in nanolithography because they are extremely strong along axial direction and yet extremely elastic along radial direction. In the simulations, the interaction of a carbon nanotube tip with silicon surfaces is explored in two regimes. In the first scenario, the nanotubes barely touch the surface, while in the second they are pushed into the surface to make "nano holes". The first - gentle scenario mimics the nanotube-surface chemical reaction induced by the vertical mechanical manipulation of the nanotube. The second -digging - scenario intends to study the indentation profiles. The following results are reported in the two cases. In the first regime, depending on the surface impact site, two major outcomes outcomes are the selective removal of either a single surface atom or a surface dimer off the silicon surface. In the second regime, the indentation of a silicon substrate by the nanotube is observed. Upon the nanotube withdrawal, several surface silicon atoms are adsorbed at the tip of the nanotube causing significant rearrangements of atoms comprising the surface layer of the silicon substrate. The results are explained in terms of relative strength of C-C, C-Si, and Si-Si bonds. The proposed method is very robust and does not require applied voltage between the nanotube tips and the surface. The implications of the reported controllable etching and hole-creating for nanolithography on silicon are discussed in detail.

Dzegilenko, Fedor N.↗
NASA NTRS2021

Anisotropic Wet Etching of Si as a Fabrication Tool Enabling 3-D Microphotonics Structures and Devices

It is shown that due to high speed and large volume of production, anisotropic wet etching of Si is a unique method of manufacturing high quality micropyramidal arrays for silicon photonics. Four types of arrays were fabricated: (i) square pyramids with the 54.7 slope of the sidewall surface, (ii) microcones with the 45 slope of sidewall surface, (iii) inverted square pyramids with 54.7 slope, and (iv) inverted triangular pyramids with different angles of the sidewalls. It is shown that the first type of arrays has a capability to produce tightly focused mid-wave infrared (MWIR) beams at the tips of the pyramids. Other arrays can be also used as light concentrators and various multifunctional microphotonic components.

Astratov, Vasily N.↗
DOE OSTI2022

System and method for repeated metal deposition-dewetting steps to form a nano-particle etching mask producing thicker layer of engraved metasurface

A method and system is disclosed for creating an optical component having a spatially controlled refractive index and uniform anti-reflective layer. The method may involve alternately depositing and dewetting two or more thin metal material layers on the substrate to form a mask having a spatially varying nano-particle distribution, and with an increased thickness beyond what could be achieved using a single, thick layer of the same material. The substrate may then be etched, using the mask, to imprint a spatially patterned nanostructure pattern on a surface the substrate in accordance with the mask.

Feigenbaum, Eyal↗
DOE OSTI2023

Facile etching for single crystal cathode materials

A recycling and synthesis of charge material for secondary batteries generates single-crystal charge materials for producing batteries with greater charge cycle longevity. Charge material particles undergo a heating for fusing or enhancing grain boundaries between polycrystalline particles. The resulting, more well-defined grain boundaries are easily etched by a relatively weak mineral acid solution. The acid solution removes material at the grain boundaries to separate secondary particles into primary particles along the grain boundaries. The resulting single crystal (monocrystalline) charge material particles are washed and filtered, and typically re-sintered to accommodate any needed lithium (lithium carbonate), and result in a charge material with larger surface area, higher lithium diffusivity and lower cation ordering.

Wang, Yan↗
DOE OSTI2024

Growth of Native Oxides of Niobium Thin Films for Superconducting Qubits with Etching Chemistry

Niobium thin films have been broadly applied in building superconducting qubits for quantum computing hardware. While improvements have been made by device engineering efforts, scaling the energy-sensitive quantum system requires materials study for further improvements. In this study, we performed XPS and ToF-SIMS analysis for Nb thin films across samples with different manufacturing techniques. By varying the air exposure time of the samples, this research comparatively investigates the chemical and depth profile of native oxides before and after the etching process. We observe a rapid logarithmic growth of oxide thickness across all samples and the dominant presence and growth of Niobium pentoxide in atomic percentage concentration on the surface. This comparative study provides insight into oxides mitigation strategies and correlation with qubits performance.

Lei, Zhicheng↗
DOE OSTI2024

Self-terminating etching processes for post-processing of 3D printed metal alloys

A process is provided to remove a selective amount of material from a metal part fabricated by additive manufacturing in a self-terminating manner. The process can be used to remove support structures and trapped powder from a metal part as well as to smooth surfaces of a 3D printed metal part. In one embodiment, selected surfaces of the metal part are treated to make the selected surfaces at least one of mechanically and chemically unstable. The unstable portion of the metal support can then be removed chemically, electrochemically, with a pressure differential, and/or through vapor-phase etching. In one embodiment, the metal part may comprise one or more of an aluminum alloy, a titanium alloy, and a copper alloy. The process can be used to modify any fluid or vapor-accessible regions and surfaces of a 3D printed metal part.

Hildreth, Owen J.↗
DOE OSTI2024

Silicon-carbide-on-insulator via photoelectrochemical etching

Silicon carbide on insulator is provided by bonding bulk silicon carbide to a substrate with an oxide-oxide fusion bond, followed by thinning the bulk silicon carbide as needed. A doping-selective etch for silicon carbide is used to improve thickness uniformity of the silicon carbide layer(s).

Lukin, Daniil M.↗
DOE OSTI2025

Dehydrogenation vs Apparent Hydrogenation: Unraveling the Mechanisms of He and O 2 Plasma Etching on Colloidal Nanocrystal Films

Removing organic ligands from colloidal nanoparticles is critical for fabricating solid-state devices, yet accurately quantifying this removal remains a significant analytical challenge. Here, we establish a robust and accessible method for this quantification by calibrating Raman spectroscopy against precise ion beam analysis (IBA) for nanoparticle assemblies (CNAs) processed by helium (He) and oxygen (O 2 ) plasmas. We demonstrate that the calibration curves are remarkably independent of plasma power and pressure, depending critically only on the choice of feed gas. He plasma induces rapid dehydrogenation and cross-linking, evidenced by a much faster decrease in the C–H Raman signal relative to the actual carbon loss. Conversely, O 2 plasma leads to a surprising “apparent hydrogenation”, where the carbon backbone is removed significantly faster than the C–H signal diminishes. This counterintuitive effect is explained by a serial mechanism of oxidative fragmentation; β-scission cleaves the alkyl chains, and subsequent stabilization steps enrich the remaining film with hydrogen-rich methyl-terminated fragments, while carbon is efficiently removed as volatile CO. This work provides calibrated functions that enable the rapid determination of absolute carbon content in processed CNAs using simple Raman spectroscopy with uncertainties of ∼8% for O 2 and ∼12% for He plasma, offering a vital tool for both process diagnostics and fundamental studies of plasma–matter interactions in colloidal nanocrystal films.

Animal feed↗
DOE OSTI2021

WhiteWind: White Etching Crack (WEC) Bearing Failures in Wind Turbine: Cooperative Research and Development, CRADA Number CRD-18-00758 (Final Report)

A WEC is a particularly aggressive, unpredictable and wide spread rolling element bearing failure mode that is common for large multi-megawatt (MW) wind turbines. WEC is considered the single most expensive failure mode for all wind turbine components, and there is currently no commercial solution. The Technical University of Denmark (DTU) is leading the WhiteWind project to investigate WECs through funding provided by the Innovation Fund Denmark. Other project partners include Vestas, SKF, Expanite, Rheinisch-Westfalische Technische Hochschule Aachen University (RWTH Aachen), and Argonne National Laboratory. The objective of the overall project is to develop a new surface engineered WEC-resistant bearing material using novel surface engineering techniques that shall provide a commercially competitive alternative to existing wind turbine bearings. NREL will support the project by providing existing measured bearing loads and validating models of drivetrain loads.

17 WIND ENERGY↗
DOE OSTI2024

Data and Code for Atomic Scale Etching of Diamond: Insights from Molecular Dynamics Simulations

This work investigates the effects of argon ions, hydrogen atoms, and hydrogen ions on the diamond (100) surface using classical molecular dynamics simulations. The purpose of this investigation was to asses plasma processing techniques for applications in quantum device manufacturing. The simulations suggest that combining argon ion smoothing with selective, near threshold energy H removal of amorphous C could be an effective strategy for diamond surface engineering, leading to more reliable and sensitive diamond color center devices. Results were found to differ significantly with interatomic potential, and an analysis of these differences was also carried out. Included in this repository are LAMMPS source files, input scripts, and plotting scripts required to reproduce the data. Also included are the output data required to make all the plots included in the associated publication.

Brenner↗
NASA NTRS2012

Inductively Coupled Plasma Etching for Delineation of InAs/GaSb Pixels

We developed 320x256 Complimentary Barrier Infrared (CBIRD) focal plane array (FPA) for long wave infrared (LWIR) imaging application. The FPA layers grown by molecular beam epitaxy (MBE) had 300 periods 1.9 micro m thick absorber. The CBIRD arrays showed the mean dark current density of 2.2 x 10(exp -4) A/cm2, when 128 mV bias voltage was applied. The long wave cut off was observed at 8.8 micrometers at the 50% peak and the maximum quantum efficiency was 54% at 5.6 micrometers. The arrays had 81% fill factor with 97% operability with noise equivalent difference temperature (NE(delta)T) of 18.6 mK and a mean detectivity of D*=1.3 x 10(exp 11) Hz(exp 1/2)/W.

InAs/GaSb↗