SEARCH · Engineering Papers

Results for “silicon processing”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,801 records · Page 100

All sources NASA NTRS DOE OSTI

DOE OSTI2017

Nanostructured Bulk-Heterojunction Solar Cells Based on Amorphous Carbon

Amorphous carbon (a-C) has the potential to provide properties important to solar photovoltaics that are comparable to those of silicon-based materials with further advantages such as low cost, solution processing, air stability, and higher thermal resistance. We employ accurate computational approaches to explore and understand active layers based on bulk heterojunctions containing a-C. Our results show that interfaces with a-C and other carbon nanostructures could enable successful electron and hole extraction as well as reduced sources for carrier recombination. Ab initio molecular dynamics and density functional theory calculations are carried out for a large statistical set of interfaces between a-C structures of different densities and either carbon nanotubes or fullerenes. Here, we show that the energy alignment at such interfaces can be widely tuned as a function of a-C density, doping chemistry, or nanostructure size to obtain type-II heterostructures and that the optical properties of such interfaces would be highly favorable for sunlight harvesting.

14 SOLAR ENERGY↗

DOE OSTI2024

Direct-bonded diamond membranes for heterogeneous quantum and electronic technologies

Diamond has superlative material properties for a broad range of quantum and electronic technologies. However, heteroepitaxial growth of single crystal diamond remains limited, impeding integration and evolution of diamond-based technologies. Here, we directly bond single-crystal diamond membranes to a wide variety of materials including silicon, fused silica, sapphire, thermal oxide, and lithium niobate. Our bonding process combines customized membrane synthesis, transfer, and dry surface functionalization, allowing for minimal contamination while providing pathways for near unity yield and scalability. We generate bonded crystalline membranes with thickness as low as 10 nm, sub-nm interfacial regions, and nanometer-scale thickness variability over 200 by 200 μm 2 areas. We measure spin coherence times T 2 for nitrogen vacancy centers in 150 nm-thick bonded membranes of up to 623 ± 21 μs, suitable for advanced quantum applications. We demonstrate multiple methods for integrating high quality factor nanophotonic cavities with the diamond heterostructures, highlighting the platform versatility in quantum photonic applications. Furthermore, we show that our ultra-thin diamond membranes are compatible with total internal reflection fluorescence (TIRF) microscopy, which enables interfacing coherent diamond quantum sensors with living cells while rejecting unwanted background luminescence. The processes demonstrated herein provide a full toolkit to synthesize heterogeneous diamond-based hybrid systems for quantum and electronic technologies.

color center↗

DOE OSTI2017

Observation of Third-order Nonlinearities in Graphene Oxide Film at Telecommunication Wavelengths

All-optical switches have been considered as a promising solution to overcome the fundamental speed limit of the current electronic switches. However, the lack of a suitable third-order nonlinear material greatly hinders the development of this technology. Here in this paper we report the observation of ultrahigh third-order nonlinearity about 0.45 cm 2 /GW in graphene oxide thin films at the telecommunication wavelength region, which is four orders of magnitude higher than that of single crystalline silicon. Besides, graphene oxide is water soluble and thus easy to process due to the existence of oxygen containing groups. These unique properties can potentially significantly advance the performance of alloptical switches.

36 MATERIALS SCIENCE↗

DOE OSTI2018

A Novel Dual-Step Nucleation Pathway in Crystalline Solids under Neutron Irradiation

Innovations in nanostructuring of inorganic crystalline solids are often limited by prerequisite critical nucleation energy and solute supersaturation for formation of a phase. This research provides direct evidence supporting the viability of an unconventional irradiation-induced nanostructuring process, via transmission electron microscopy, that circumvents these preconditions. Using polymorphic silicon carbide (SiC) as a prototype, a surprising two-step nucleation route is demonstrated through which nanoscale distribution of the second phase is achieved by reaction of solutes with neutron irradiation-induced precursors. In the first step, nanoscale α–SiC precipitates in a β–SiC matrix unexpectedly nucleate heterogeneously at structural defects. This occurs at significantly lower temperatures compared with the usual β→α transition temperature. Subsequently, α–SiC precipitate acts as a surrogate template for its structural and compositional transition into a fission product precipitate, palladium silicide. These discoveries provide a modern view of irradiation engineering in polymorphic ceramics for advanced applications.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Plant-based CO 2 drawdown and storage as SiC

Since the 1950's the Earth's natural carbon cycle has not sufficiently sequestrated excess atmospheric CO 2 contributed by human activities. CO 2 levels rose above 400 ppm in 2013 and are forecasted to exceed 500 ppm by 2070, a level last experienced during the Paleogene period 25–65 MYA. While humanity benefits from the extraction and combustion of carbon from Earth's crust, we have overlooked the impact on global climate change. Here, we present a strategy to mine atmospheric carbon to mitigate CO 2 emissions and create economically lucrative green products. We employ an artificial carbon cycle where agricultural plants capture CO 2 and the carbon is transformed into silicon carbide (SiC), a valuable commercial material. By carefully quantifying the process we show that 14% of plant-sequestered carbon is stored as SiC and estimate the scale needed for this process to have a global impact.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2017

An Artificial Retina Processor for Track Reconstruction at the LHC Crossing Rate

The goal of the INFN-RETINA R&D project is to develop and implement a computational methodology that allows to reconstruct events with a large number (> 100) of charged-particle tracks in pixel and silicon strip detectors at 40 MHz, thus matching the requirements for processing LHC events at the full bunch-crossing frequency. Our approach relies on a parallel pattern-recognition algorithm, dubbed artificial retina, inspired by the early stages of image processing by the brain. In order to demonstrate that a track-processing system based on this algorithm is feasible, we built a sizable prototype of a tracking processor tuned to 3 000 patterns, based on already existing readout boards equipped with Altera Stratix III FPGAs. The detailed geometry and charged-particle activity of a large tracking detector currently in operation are used to assess its performances. We report on the test results with such a prototype.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2025

Preliminary hyperspectral neutron radiography of binder jet 3D printed and melt infiltrated Si–SiC

The preliminary results of hyperspectral neutron radiography of Si–SiC made with binder jet additive manufacturing, subsequent carbon addition, and silicon melt infiltration are presented. The samples were measured in the processing states before and after the melt infiltration to determine if neutrons would help characterize the microstructure to better understand the melt infiltration process. Theoretical Bragg edges were calculated for comparison with the radiographic results. The changes in the Bragg edges from pre- to post-infiltrated reaction-bonded SiC were evident, that could be used to address the differences in microstructures. In conclusion, the preliminary results presented in this study demonstrated that neutron Bragg-edge imaging is possible with Si–SiC reaction-bonded ceramics and can help determine the microstructure of melt infiltrated samples.

SiC↗

DOE OSTI2017

Hardware-Software Complex for Measurement of Energy and Angular Distributions of Charged Particles Formed in Nuclear Reactions

A hardware-software complex for measurement of energy and angular distributions of charged particles formed in nuclear reactions is presented. Hardware and software structures of the complex, the basic set of the modular nuclear-physical apparatus of a multichannel detecting system on the basis of ΔE–E telescopes of silicon detectors, and the hardware of experimental data collection, storage, and processing are presented and described.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2017

Energy dependent forward $B \rightarrow J/\psi$ measurements in $p+p$ collisions at PHENIX

The heavy flavor studies at RHIC help improve the knowledge of the bottom/charm quark production and can test Quantum Chromodynamics (QCD). Compared to the LHC/Tevatron, the RHIC heavy flavor production originates from different partonic sub-processes and has a complementary kinematic coverage. The PHENIX forward rapidity silicon vertex detector (FVTX) provides precise determination of the event vertex, tracking and the Distance of Closest Approach (DCA) of charged tracks. This detector allows direct access to the B meson production via measurements of non-prompt J/ψ→μ + +μ - within 1.2<|y|<2.2 rapidity in p+p collisions at √s= 510 and 200 GeV. Comparison among PHENIX measurements of the B→J/ψ fraction with integrated J/ψ p T up to 5 GeV/c and higher energy results at the Tevatron and the LHC presents a smooth center of mass energy dependence from 0.2 to 13 TeV in p+p (p+$\bar{p}$) collisions. The Next-To-Leading order Perturbative QCD (NLO pQCD) calculations are in reasonable agreement with the extracted total $b\bar{b}$ cross section based on the B→J/ψ fraction measurements at PHENIX.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2017

Diffraction-Based Optical Switching with MEMS

In this article, we are presenting an overview of MEMS-based (Micro-Electro-Mechanical System) optical switch technology starting from the reflective two-dimensional (2D) and three-dimensional (3D) MEMS implementations. To further increase the speed of the MEMS from these devices, the mirror size needs to be reduced. Small mirror size prevents efficient reflection but favors a diffraction-based approach. Two implementations have been demonstrated, one using the Texas Instruments DLP (Digital Light Processing), and the other an LCoS-based (Liquid Crystal on Silicon) SLM (Spatial Light Modulator). These switches demonstrated the benefit of diffraction, by independently achieving high speed, efficiency, and high number of ports. We also demonstrated for the first time that PSK (Phase Shift Keying) modulation format can be used with diffraction-based devices. To be truly effective in diffraction mode, the MEMS pixels should modulate the phase of the incident light. We are presenting our past and current efforts to manufacture a new type of MEMS where the pixels are moving in the vertical direction. The original structure is a 32 x 32 phase modulator array with high contrast grating pixels, and we are introducing a new sub-wavelength linear array capable of a 310 kHz modulation rate

36 MATERIALS SCIENCE↗

NASA NTRS1971

A lightweight, high output soil sampler

Sampler is useful on or under earth's surface or on sea bottom. Larger sample amount is obtained relative to sampler size and weight and limited particle size sample material is continuously delivered. Silicone rubber linear in transport tube nearly eliminates grinding or particulate processing during sampling, and reduces required torque.

Howard, E. A.↗

NASA NTRS1973

Comments on 'Elastically scattered recoil nuclei in solid-state detectors'

Horn and Von Oertzen (1967) have shown that tracks in mica are produced by an irradiation with 32-MeV O-16 ions. These tracks were attributed to K and Fe recoils produced by elastic scattering of the incident oxygen beam. In the present work an alternate explanation of their observations is provided. The measured characteristics of the tracks are shown to be compatible with theoretical predictions for production of tracks by inelastic (mostly compound nucleus) reactions with silicon and to be inconsistent with the previously proposed elastic scattering process. The possibility that the tracks are produced by contaminant ions in the beam cannot be ruled out.

Maurette, M.↗

NASA NTRS1977

Advanced high efficiency wraparound contact solar cell

A significant advancement in the development of thin high efficiency wraparound contact silicon solar cells has been made by coupling space and terrestrial processing procedures. Although this new method for fabricating cells has not been completely reduced to practice, some of the initial cells have delivered over 20 mW/sq cm when tested at 25 C under AMO intensity. This approach not only yields high efficiency devices, but shows promise of allowing complete freedom of choice in both the location and size of the wraparound contact pad area

Scott-Monck, J. A.↗

NASA NTRS1977

Advanced high efficiency wraparound contact solar cell

Scott-Monck, J. A.↗

NASA NTRS1977

Semiconductor grade, solar silicon purification project

The conversion of metallurgical grade silicon into semiconductor grade silicon by way of a three step SiF2 polymer transport purification process was investigated. Developments in the following areas were also examined: (1) spectroscopic analysis and characterization of (SiF2) sub x polymer and Si sub x F sub y homologue conversion; (2) demonstration runs on the near continuous apparatus; (3) economic analysis; and (4) elemental analysis.

Ingle, W. M.↗

NASA NTRS1981

CADAT multiport placement and routing

CADAT multiport-in-two dimensions program (MP2D) is powerful placement and routing aid for processing double-ended cell equivalents of high-speed silicon-onsapphire (SOS) standard-cell family. Basic purpose of MP2D is to design high-density large-integrated (LSI) arrays.

Source record↗

NASA NTRS1981

Fabrication of injection molded sintered alpha SiC turbine components

Fabrication of a sintered alpha silicon carbide turbine blade by injection molding is described. An extensive process variation matrix was carried out to define the optimum fabrication conditions. Variation of molding parameters had a significant impact on yield. Turbine blades were produced in a reasonable yield which met a rigid quality and dimensional specification. Application of injection molding technology to more complex components such as integral rotors is also described.

Storm, R. S.↗

NASA NTRS1982

Interaction between cast silicon properties and solar cell performance

Three types of cast silicon, Silso, HEM (Heat-Exchanger Method) and UCP (Ubiquitous Crystallization Process) were studied for their use as solar cells. Optical microscopy after etching revealed a high density of uniform dislocations (approaching 1,000,000/sq cm), lines of dislocations indicating stress during crystal growth, and precipitates, some of which generate dislocations. Solar cells were fabricated by three processes. Results of solar cell processing revealed that these materials produce cells of lower efficiency than Czochralski control cells, and that the efficiencies of the three materials were quite close. Diffusion length and spectral response data are shown. Certain structural features are correlated with solar cell efficiency, diffusion length, and spectral response. Electron-beam induced current (EBIC) and light spot scanning are used to back up other measurements.

Hyland, S.↗

Refine your search to explore more results.