SEARCH · Search NASA

Results for “Electronic Devices”

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 325 records · Page 18

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Design of 3D Oxide–Metal Hybrid Metamaterial for Tailorable Light–Matter Interactions in Visible and Near-Infrared Region

Dielectric–metallic hybrid metamaterials exhibit extraordinary optical properties due to the light–matter interactions at the dielectric–metallic interfaces. The ability in precision control of the light–matter interactions in nanoscale is key to tailor the optical properties of hybrid metamaterials. In this work, a complex 3D framework of multilayered self-assembled BaTiO 3 (BTO)-Au hybrid thin films is demonstrated with such precision control of the light–matter interaction in nanoscale. Here, unique “bamboo-like” Au nanostructures are formed via the bilayer and trilayer stacking of BTO-Au hybrid layers with interlayers of SrTiO 3 , CeO 2 , or MgO. Different film strain states introduced by the three interlayers result in variable diameter and density of Au nanopillars. Both simulated and experimental optical data demonstrate the localized surface plasmon resonance change and hyperbolic dispersion wavelength shift in visible to near-infrared because of the effective tuning of the Au nanopillar aspect ratio and free electron density. The highly tunable optical properties along with the ferroelectric behavior and thermal robustness of the 3D hybrid film enable it to be a great candidate for multifunctional applications. This study demonstrates a unique 3D approach for precision optical property tuning and combined functionalities in oxide–metal metamaterial systems toward future integrated photonic and electronic devices.

36 MATERIALS SCIENCE↗

DOE OSTI2022

High Velocity, Low‐Voltage Collective In‐Plane Switching in (100) BaTiO 3 Thin Films

Abstract Ferroelectrics are being increasingly called upon for electronic devices in extreme environments. Device performance and energy efficiency is highly correlated to clock frequency, operational voltage, and resistive loss. To increase performance it is common to engineer ferroelectric domain structure with highly‐correlated electrical and elastic coupling that elicit fast and efficient collective switching. Designing domain structures with advantageous properties is difficult because the mechanisms involved in collective switching are poorly understood and difficult to investigate. Collective switching is a hierarchical process where the nano‐ and mesoscale responses control the macroscopic properties. Using chemical solution synthesis, epitaxially nearly‐relaxed (100) BaTiO 3 films are synthesized. Thermal strain induces a strongly‐correlated domain structure with alternating domains of polarization along the [010] and [001] in‐plane axes and 90° domain walls along the [011] or [01] directions. Simultaneous capacitance–voltage measurements and band‐excitation piezoresponse force microscopy revealed strong collective switching behavior. Using a deep convolutional autoencoder, hierarchical switching is automatically tracked and the switching pathway is identified. The collective switching velocities are calculated to be ≈500 cm s −1 at 5 V (7 kV cm −1 ), orders‐of‐magnitude faster than expected. These combinations of properties are promising for high‐speed tunable dielectrics and low‐voltage ferroelectric memories and logic.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Polycaprolactone‐Based Zinc Ink for High Conductivity Transient Printed Electronics and Antennas

Abstract Distributed sensors and electronics can be used in agriculture to optimize crop management and improve environmental outcomes. Electronic devices in these outdoor spaces require medium to long range (>1m) wireless communication of data over several weeks or months, which in turn requires high conductivity (1 × 10 5 Sm −1 ) antennas. Printed bioinert or ecoresorbable conductors, comprising carbon, magnesium, or zinc fillers, typically exhibit conductivity on the order of 10–1000 Sm −1 and lifetimes from a few hours to a few days. A print‐based fabrication process for chemically treated zinc traces, which achieves conductivity of up to 6 × 10 5 Sm −1 is reported here. The ink formulation uses a non‐water‐soluble soil biodegradable polycaprolactone binder. The ink and printing processes reported here led to stable conductive traces that are used in ultra high frequency radio frequency identification (UHF‐RFID) folded dipole antennas operating at 915 MHz. The conductivity of the printed traces is maintained for over 70 days in ambient environments when traces are protected by a biodegradable beeswax encapsulation layer.

Baumbauer, Carol L.↗

DOE OSTI2024

3D Ferroelectric Phase Field Simulations of Polycrystalline Multi‐Phase Hafnia and Zirconia Based Ultra‐Thin Films

Abstract HfO 2 – and ZrO 2 –based ferroelectric thin films have emerged as promising candidates for the gate oxides of next‐generation electronic devices. Recent work has experimentally demonstrated that a tetragonal/orthorhombic (t/o‐) phase mixture with partially in‐plane polarization can lead to negative capacitance (NC) stabilization. However, there is a discrepancy between experiments and the theoretical understanding of domain formation and domain wall motion in these multi‐phase, polycrystalline materials. Furthermore, the effect of anisotropic domain wall coupling on NC has not been studied so far. Here, 3D phase field simulations of HfO 2 – and ZrO 2 –based mixed‐phase ultra‐thin films on silicon are applied to understand the necessary and beneficial conditions for NC stabilization. It is found that smaller ferroelectric grains and a larger angle of the polar axis with respect to the out‐of‐plane direction enhances the NC effect. Furthermore, it is shown that theoretically predicted negative domain wall coupling even along only one axis prevents NC stabilization. Therefore, it is concluded that topological domain walls play a critical role in experimentally observed NC phenomena in HfO 2 – and ZrO 2 –based ferroelectrics.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2024

Distinct Composition‐Dependent Topological Hall Effect in Mn 2‐x Zn x Sb

Abstract Spintronics, an evolving interdisciplinary field at the intersection of magnetism and electronics, explores innovative applications of electron charge and spin properties for advanced electronic devices. The topological Hall effect (THE), a key component in spintronics, has gained significance due to emerging theories surrounding noncoplanar chiral spin textures. This study focuses on Mn 2‐x Zn x Sb, a material crystalizing in centrosymmetric space group with rich magnetic phases tunable by Zn contents. Through comprehensive magnetic and transport characterizations, we found that the high‐Zn ( x > 0.6) samples display THE which is enhanced with decreasing temperature, while THE in the low‐Zn ( x < 0.6) samples show an opposite trend. The coexistence of those distinct temperature dependencies for THE suggests very different magnetic interactions/structures for different compositions and underscores the strong coupling between magnetism and transport in Mn 2‐x Zn x Sb. The findings contribute to understanding topological magnetism in centrosymmetric tetragonal lattices, establishing Mn 2‐x Zn x Sb as a unique platform for exploring tunable transport effects and opening avenues for further exploration in the realm of spintronics.

Nabi, Md Rafique Un↗

DOE OSTI2022

Synthesis and Mechanical Properties of sub 5‐μm PolyUiO‐66 Thin Films on Gold Surfaces

Abstract Metal‐organic framework (MOF) thin films currently lack the mechanical stability needed for electronic device applications. Polymer‐based metal‐organic frameworks (polyMOFs) have been suggested to provide mechanical advantages over MOFs, however, the mechanical properties of polyMOFs have not yet been characterized. In this work, we developed a method to synthesize continuous sub‐5 μm polyUiO‐66(Zr) films on Au substrates, which allowed us to undertake initial mechanical property investigations. Comparisons between polyUiO‐66 and UiO‐66 thin films determined polyUiO‐66 thin films exhibit a lower modulus but similar hardness to UiO‐66 thin films. The initial mechanical characterization indicates that further development is needed to leverage the mechanical property advantages of polyMOFs over MOFs. Additionally, the demonstration in this work of a continuous surface‐supported polyUiO‐66 thin film enables utilization of this emerging class of polyMOF materials in sensors and devices applications.

Frederick, Esther↗

DOE OSTI2020

Erratum to: Soft- and reactive landing of ions onto surfaces: concepts and applications

Soft- and reactive landing of mass-selected ions is gaining attention as a promising approach for the precisely-controlled preparation of materials on surfaces that are not amenable to deposition using conventional methods. A broad range of ionization sources and mass filters are available that make ion soft-landing a versatile tool for surface modification using beams of hyperthermal (<100?eV) ions. The ability to select the mass-to-charge ratio of the ion, its kinetic energy and charge state, along with precise control of the size, shape, and position of the ion beam on the deposition target distinguishes ion soft landing from other surface modification techniques. Soft- and reactive landing have been used to prepare interfaces for practical applications as well as precisely-defined model surfaces for fundamental investigations in chemistry, physics, and materials science. For instance, soft- and reactive landing have been applied to study the surface chemistry of ions isolated in the gas-phase, prepare arrays of proteins for high-throughput biological screening, produce novel carbon-based and polymer materials, enrich the secondary structure of peptides and the chirality of organic molecules, immobilize electrochemically-active proteins and organometallics on electrodes, create thin films of complex molecules, and immobilize catalytically active organometallics as well as ligated metal clusters. In addition, soft landing has enabled investigation of the size-dependent behavior of bare metal clusters in the critical subnanometer size regime where chemical and physical properties do not scale predictably with size. The morphology, aggregation, and immobilization of larger bare metal nanoparticles, which are directly relevant to the design of catalysts as well as improved memory and electronic devices, have also been studied using ion soft landing. This review article begins in section 1 with a brief introduction to the existing applications of ion soft- and reactive landing. Section 2 provides an overview of the ionization sources and mass filters that have been used to date for soft landing of mass-selected ions. A discussion of the competing processes that occur during ion deposition as well as the types of ions and surfaces that have been investigated follows in section 3. Section 4 discusses the physical phenomena that occur during and after ion soft landing, including retention and reduction of ionic charge along with factors that impact the efficiency of ion deposition. The influence of soft landing on the secondary structure and biological activity of complex ions is addressed in section 5. Lastly, an overview of the structure and mobility as well as the catalytic, optical, magnetic, and redox properties of bare ionic clusters and nanoparticles deposited onto surfaces is presented in section 6. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35:439–479, 2016.

Johnson, Grant E.↗

DOE OSTI2022

Epitaxially crystallized polyethylene exhibiting near‐equilibrium melting temperatures*

Abstract The morphology and orientation of polymer crystals are important factors which determine the performance of thin‐film, polymer‐based technologies such as organic electronic devices and gas separation membranes. Here, we utilize polymer‐substrate epitaxy to achieve a highly oriented crystalline morphology during thin‐film processing. To accomplish this, we employ matrix‐assisted pulsed laser evaporation (MAPLE), a slow physical vapor deposition process, to deposit linear polyethylene epitaxially atop a graphene substrate. Via MAPLE, we demonstrate the ability to achieve a film morphology comprised of well‐aligned, edge‐on crystalline lamellae. Furthermore, we show that MAPLE can be exploited to grow crystalline lamellae composed entirely of extended polymer chains which exhibit a near‐equilibrium melting temperature. Our study demonstrates that MAPLE, as a bottom‐up approach, can deposit polymer thin films with improved control over crystalline morphology.

Wang, Yucheng↗

DOE OSTI2020

Tubulin Double Helix: Lateral and Longitudinal Curvature Changes of Tubulin Protofilament

By virtue of their native structures, tubulin dimers are protein building blocks that are naturally pre-programmed to assemble into cytoskeletal polymers known as microtubules (MTs). Here we demonstrate polycation-directed (i.e. electrostatically tunable) assembly of tubulins through tubulin protofilament conformational changes in the longitudinal and lateral directions, creating novel tubulin double helices and various tubular architectures. Synchrotron small angle X-ray scattering and transmission electron microscopy reveal a remarkable range of nanoscale assembly structures: single- and double-layered double-helix tubulin tubules. The phase transitions from MTs into the new assemblies are dependent on the size and concentration of polycations. Two characteristic scales that determine the number of observed phases are the size of polycation compared to the size of tubulin (≈4 nm) and MT diameter (≈25 nm). This work suggests the feasibility of “programmable breakdown” of protein nanotubes, tearing MTs into double-stranded tubulins and building up previously undiscovered nanostructures, by using polycations with scissor- and glue-like properties. Importantly, we define a new role of tubulins as two-dimensionally shape-controllable building blocks for novel supramolecular architectures. Furthermore, these findings provide insight into the design of protein-based functional materials, for example, as metallization templates for nanoscale electronic devices, kinesin motor-driving molecular screws, and anticancer drug delivery vehicles.

2D shape‐control↗

DOE OSTI2021

Rapid In Situ Ligand‐Exchange Process Used to Prepare 3D PbSe Nanocrystal Superlattice Infrared Photodetectors

Abstract Colloidal semiconductor nanocrystals are important building blocks for low‐cost, solution‐processed electronic devices with tunable functionalities. Considerable progress is made in improving charge transport through nanocrystal films by exchanging long insulating ligands with shorter passivating ligands. To take full advantage of this strategy, it is equally important to fabricate close‐packed structures that reduce the average interparticle spacing. Yet it remains a challenge to retain long‐range, close‐packed order after ligand exchange. Here, a novel one‐step in situ ligand‐exchange method is demonstrated that enables rapid (5 min) ligand exchange of nanocrystal films, which are more than 50 layers thick. Using this simple and efficient method, it is shown that the face‐centered cubic ordering of 500 nm thick PbSe nanocrystal films is retained after ligand exchange from oleic acid to benzoic acid. Moreover, it is demonstrated that PbSe nanocrystal photodetectors with a well‐ordered structure have superior optoelectronic properties compared to disordered films; ordered films have a 16× higher responsivity of ≈0.25 A W −1 at 1 V and a 2× faster response time. As far as it is known, this is the first report to realize a rapid one‐step ligand exchange through a thick superlattice film with retention of long‐range order.

infrared detecton↗

DOE OSTI2026

Ohmic contact formation at the Au/Sr 3 Ir 2 O 7 interface

Here, using X-ray photoelectron spectroscopy (XPS), we show that Au forms an Ohmic contact with the surface of the narrow-bandgap Mott insulator Sr 3 Ir 2 O 7 thin films. XPS reveals no significant binding energy shift with increasing Au overlayer thickness on epitaxial Sr 3 Ir 2 O 7 (001) thin films, consistent with the linear current-voltage (I-V) behavior and indicative of negligible band bending. The absence of Schottky barrier formation at the Au/Sr 3 Ir 2 O 7 interface corroborates the metallic surface character of the Sr 3 Ir 2 O 7 thin film, as observed in angle-resolved photoemission spectroscopy (ARPES) studies, suggesting that the interface behaves effectively as a metal-on-metal contact. Furthermore, XPS points to the presence of distinct surface/interface and bulk electronic states for Sr 3 Ir 2 O 7 . This study provides critical material information for designing iridate-based electronic devices.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Charge carrier transport in thin conjugated polymer films: influence of morphology and polymer/substrate interactions

The performance of conjugated polymer (CP)-based electronic devices relies on optimal charge carrier mobilities, which are determined by monomeric architecture, degree of polymerization, chain conformation, and the nano- and mesoscale morphologies. With regard to the latter, we discuss two effects that have received limited attention in the literature, yet important for device performance optimization: (1) the role of morphological disorder and of CP/substrate interactions on the in-plane and out-of-plane carrier transport in CPs; (2) the impact of morphological disorder on charge transfer at the CP/substrate interface. The emergence of film thickness-dependent carrier mobilities, varying over two orders of magnitude within a length scale of 200 nm, and band-bending phenomena, extending tens of nanometers within the CP, are associated with these effects. These findings suggest areas for further research in order to enable widespread applications of next-generation CP-based devices.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Multifractal detrended fluctuation analysis of soil radon ( 222 Rn) and thoron ( 220 Rn) time series

In this paper, we present results of Multifractal Detrended Fluctuation Analysis (MF-DFA) of soil Radon ( 222 Rn) and Thoron ( 220 Rn) time series to examine the scaling and multifractal features. Data consists of 15,692 measurements taken each over forty-minute interval. RTM 1688-2, 222 Rn/ 220 Rn electronic device has been used for measurement purposes. Seasonal periodicities have been removed from the data and MF-DFA was employed on de-seasonalized data. Original 222 Rn and 220 Rn time series have been converted into surrogate and shuffled time series. MFDFA has also been applied to the surrogate and shuffled series to examine the multifractality nature. Results of the study show that $^{222}_{Orig}Rn$, $^{222}_{Surr}Rn$ and $^{220}_{Orig}Rn$, $^{220}_{Surr}Rn$ time series are longrange positively correlated and an increase or decrease in either of radionuclide concentrations will be followed by another increase or decrease of concentrations in future measurements. The $^{220}_{Shuff}Rn$ time series has an independent or short-range dependent structure called white noise and the shuffled time series exhibit a very weak multifractality.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2022

n-Type doping of a solution processed p-type semiconductor using isoelectronic surface dopants for homojunction fabrication

The p-n junction is one of the fundamental requirements for a practical semiconductor-based electronic device. Designing a heterojunction comprising of dissimilar p-type and n-type semiconductors calls for careful energy level considerations, both when selecting the semiconductor materials as well as the metal contacts. A homojunction based on a single semiconductor simplifies this task, as energy levels of the p-type and n-type materials are already fairly similar, allowing for easier selection of contacts. Traditionally, homojunctions rely on doping of a bulk semiconductor to achieve p- and n-type transport through controlled addition of aliovalent dopants via energy-intensive processes such as ion implantation or thermal annealing. Exact control of doping in nanocrystalline semiconductors is significantly more challenging, due to self-purification effects. However, owing to their large surface areas, surface moieties can be utilized to both dope the nanostructures as well as tune their energy levels. Here, we present a facile technique based on an isoelectronic surface dopant in order to achieve p- and n-type materials based on the same semiconductor. We show that thin p-type colloidal Bi 2 Te 3 nanowires can be switched to n-type through surface functionalization, thus increasing the availability of new nanocrystalline solution-processable p-n homojunctions.

42 ENGINEERING↗

DOE OSTI2024

Ghost states and surface structures of the charge density wave kagome metal ScV 6 Sn 6

In this work, we investigate the high-temperature phase of the kagome metal ScV 6 Sn 6 using scanning tunneling microscopy/spectroscopy (STM/S) and density functional theory calculations. STM topographic images of the cleaved sample reveal two distinct surface terminations: flat islands with Sn termination and trenches terminated by kagome layers with Sn as the outermost atomic layer. STS measurements on the Sn-terminated and kagome-terminated surfaces show significant differences, in particular the presence of large density of states near the Fermi level in the former case. Our first-principles calculations reveal that the charge density on the kagome-terminated surface gives rise to “ghost states” which show intensity away from surface atoms, arising due to hybridization of orbitals above the surface. These states can obscure the intrinsic properties of the surface, potentially leading to misattribution of the surface termination. This underscores the need for careful interpretation in STM studies, especially when discerning surface states of localized states. Understanding the surface structure of this versatile quantum material provides essential information for interpreting surface-sensitive experiments, tailoring material properties, engineering interfaces, and controlling stability and reactivity. This knowledge paves the way for further exploration and potential applications of kagome lattice materials in various fields, including quantum computing, topological physics, and advanced electronic devices.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Integral boundary conditions in phase field models

Modeling the chemical, electric and thermal transport as well as phase transitions and the accompanying mesoscale microstructure evolution within a material in an electronic device setting involves the solution of partial differential equations often with integral boundary conditions. Employing the familiar Poisson equation describing the electric potential evolution in a material exhibiting insulator to metal transitions, we exploit a special property of such an integral boundary condition, and we properly formulate the variational problem and establish its well-posedness. Next, we compare our method with the commonly-used Lagrange multiplier method that can also handle such boundary conditions. Numerical experiments demonstrate that our new method achieves optimal convergence rate in contrast to the conventional Lagrange multiplier method. Furthermore, the linear system derived from our method is symmetric positive definite, and can be efficiently solved by Conjugate Gradient method with algebraic multigrid preconditioning.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2020

Synthesis of graphene-like carbon from biomass pyrolysis and its applications

Two-dimensional graphene materials attracted much attention worldwide because of their superior performance in electronic devices, sensors, and energy storage. However, its application is limited by high cost and insufficient production. The work to find out a simple and environmentally friendly process is highly needed. Designed pyrolysis of biomass precursors can derive graphene-like materials. This review summarizes some typical preparation processes for graphene-like materials synthesis from biomass carbonization via pyrolysis, including salt-based activation, template-based confinement, chemical blowing, coupling with hydrothermal carbonization pretreatment, post exfoliation, and some other methods. The operation of these methods and the performance of obtained graphene-like materials were closely highlighted. The scalability of the techniques and the applications of the biomass graphene-like carbon were also discussed. Some advanced characterization methods, such as SEM, TEM, AFM, Raman, and XPS to determine the graphene-like structure and graphitization degree were also discussed. In the end, some current challenges and future perspectives of the synthesis of these graphene-like materials were concluded.

pyrolysis, graphene, biomass, application, scalabi↗

DOE OSTI2025

Bipolar transport in diamond under photo-excitation: Evidence of free charge scattering by excitons

The fundamental characteristics of the Coulomb e-h interactions in ultra-pure diamond are investigated through time-resolved photoconductivity measurements in homogeneously photoexcited samples with ohmic-like low resistive B + sandwich contacts. Here, we demonstrate that, in the electric field, the bipolar charge mobility exhibits drastic reduction for photo-injected densities of 10 14 ‐10 16 cm ‐3 that cannot be explained only by mutual scattering between free e-h particles. This phenomenon is clarified by adding scattering caused by excitons whose density grows in the photo-exited system. The comparison of drift mobilities at 300 K in diamond obtained in this study and in pure Si and Ge obtained from literature, where exciton scattering is insignificant, is presented. We derive the empirical expression for the density dependences of bipolar mobility for the electric fields up to 1 kV/cm that could be useful for the development of diamond electronic devices.

Bipolar drift↗