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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Evaluation of Carrier Trapping in SiNx Towards Ion Migration Measurements

Sodium ion migration has been implicated in potential induced degradation of the shunting type. The kinetics of sodium migration in silicon nitride can be investigated using a simple capacitance-voltage characterization technique. However, we show that the charge trapping strongly affects the measurement and must be taken into consideration in the experimental approach. Furthermore, we perform a systematic analysis of charge carrier trapping in silicon nitride, allowing us to correct trapping effects that otherwise prevent sodium signal detection. We extract trapping and detrapping time constants both on the order of several hours. This shows that trapping cannot be ignored as it occurs relatively quickly and is constantly evolving in time. Accurate determination of sodium behavior in dielectric layers will facilitate robust co-optimization of these layers for optical, passivation, and barrier properties.

42 ENGINEERING↗
DOE OSTI2018

Electrical Properties of p-NiO/n-Si Heterostructures Based on Nanostructured Silicon

Silicon nanowires are formed on n-Si substrates by chemical etching. p-NiO/n-Si heterostructures are fabricated by reactive magnetron sputtering. The energy diagram of anisotype p-NiO/n-Si heterostructures is constructed according to the Anderson model. The current–voltage and capacitance–voltage characteristics are measured and analyzed. The main current-transport mechanisms through the p-NiO/n-Si heterojunction under forward and reverse biases are established.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Features of MIS Structures with Samarium Fluoride on Silicon and Germanium Substrates

The electrophysical characteristics of silicon and germanium MIS structures with an SmF{sub 3} insulator film, as well as their degradation due to the effect of electric fields, although similar, have a number of specific features. The current-transmission mechanism in all studied structures is described by the power dependence. Interface traps form the charge of electrically active traps, which varies during capacitance–voltage measurements, and the charge of inactive traps, which remains invariable. This charge is negative on the n-Ge surface, and the corresponding charge on the n-type and p-type silicon surface is positive. The trap charge density in the bulk of samarium fluoride lies in the range from –0.2 × 10{sup –8} to 0.6 × 10{sup –8} C/cm{sup 2} and is negligibly small when compared with the charge of interface traps in most cases.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Electrical Characterization of Hybrid Halide Perovskites Based Heterojunction Device

Herein, we have measured the mobility of Hole’s for the configuration FTO/TiO{sub 2}/CH{sub 3}NH{sub 3}PbBr{sub 3}/PEDOT:PSS/Al by the SCLC regime. The current–voltage (I–V) characteristics of the CH{sub 3}NH{sub 3}PbBr{sub 3} perovskite based device shows the rectifying behavior as Schottky diode. Different parameters of the proposed device such as saturation current, ideality factor, barrier height have been taken out from I–V characteristics. The highest Hole’s mobility from TiO{sub 2} thin film through the perovskite and PEDOT:PSS film to the top aluminum electrode has of order 1.59 × 10{sup –4} cm{sup 2} V{sup –1} s{sup –1}. Moreover, the proposed device shows the TFSCLC regime at lower voltage while, at higher voltages it shows the TCLC regime. In addition to this, some important parameters like junction resistance, capacitance and carrier lifetime of device can be measured by the spectroscopy analysis of impedance.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Low-Temperature Annealing of Lightly Doped n-4H-SiC Layers after Irradiation with Fast Electrons

The effect of low-temperature (up to 600°C) isothermal and isochronous annealing on the electrical characteristics of irradiated n-4H-SiC JBS Schottky diodes is studied. Irradiation is performed with 0.9-MeV electrons at a dose of 1 × 10{sup 16} cm{sup –2}. It is shown that the forward current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the irradiated diodes are mainly restored at annealing temperatures of up to 300°C. As the annealing temperature is raised to 500°C, nearly 90% of the defects introduced by irradiation with fast electrons are annealed out. The possible recommended mode of stabilizing annealing to be used in radiation-defect engineering (RDE) is 500°C, 30 min.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Weak Coupling Effect on the Magnetic Freedericksz Transition in a Ferronematic Liquid Crystal

The magnetic Freedericksz transition in a ferronematic representing a diluted suspension of magnetic nanoparticles in an N-(4-methoxybenzylidene)-4-butylaniline (MBBA) nematic liquid crystal was experimentally studied. The transition point was determined by means of dielectric capacitance measurements in cells of different thickness for samples with various volume fractions of ferroparticles. The effect of weak coupling between the magnetic and liquid-crystal subsystems was studied. Low concentrations of quasispherical magnetic particles were shown to decrease the magnetic Freedericksz transition threshold in comparison with a pure liquid crystal. The obtained results were theoretically substantiated. The phase diagram of the suspension was plotted, and the method of estimating the energy of coupling between magnetic particles and a liquid-crystal matrix was proposed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

The Effect of the Fin Shape and Thickness of the Buried Oxide on the DIBL Effect in an SOI FinFET

In this paper, we simulated the dependence of the effect of reducing the drain-induced barrier lowering on the thickness of a buried oxide layer in a finned (vertical) metal-oxide-semiconductor field effect transistor (FinFET) based on silicon-on-insulator technology. Three shapes of the fin with the rectangle, trapezoid, and triangle cross sections were considered. The drain-induced barrier lowering effect significantly depends on both the fin shape and the thickness of the buried oxide layer. The smallest drain-induced barrier lowering effect occurs when the thickness of the buried oxide layer is small for the fin of a triangular shape. This behavior of the drain-induced barrier lowering effect is strongly correlated with the behavior of the parasitic capacitance between a gate and a source.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Experimental Detection of Resonant Tunneling in the Doped Structure with a Single Quantum Well by the Admittance Spectroscopy Method

The admittance measurements of heterostructures with quantum wells (QW) In{sub x}Ga{sub 1 – x}As/GaAs (0.19 ≤ x ≤ 0.3) precisely grown by the MOCVD method were carried out. By means of the admittance spectroscopy method, the resonant tunneling emission was for the first time registered as the determining mechanism inducing high-frequency conductance of doped heterostructures with QW, the separation of tunnel and resonant tunneling contributions was carried out, and the influence of tunnel component on the total rate of carrier emission from QW was analyzed. The self-consistent simulation of capacitance–voltage characteristics of the structures was performed, and the transmittance of the system formed by the Hartree potential around QW was calculated. Experimentally and by numerical calculations, it is shown that the probability of resonant tunneling emission decreases with increasing reverse bias due to the broken symmetry of the barriers.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

High Throughput Source-less Plasma Deposition of Structured Silicon Anodes for Lithium-Ion Batteries

Amprius developed a manufacturing solution for silicon nanowire anode that relies on an inexpensive, high throughput, and high gas precursor utilization plasma deposition method that uses the anode foils as electrodes for plasma generation. The capacitively couple plasma (CCP) method is used in semiconductor and photovoltaic industry and Amprius modified existing high throughput equipment to use anode foils and to deposit amorphous silicon. The equipment was installed ahead of the program at Amprius site. The rest of the tasks included foil handling and process development. The equipment passed site acceptance tests (SAT) and the process parameter mapping was completed, indicating that the target process window limits produce output materials at the rate and with yield and specifications that meet the manufacturing target criteria. Amprius has hired supporting personnel to optimize processes and run the equipment. A parallel task verified the baseline performance of the silicon anode material, to be used as reference for the new manufacturing method.

25 ENERGY STORAGE↗
DOE OSTI2026

Collaborative R&D with REEL Solar Inc (REEL) to Understand and Overcome Performance Limitations in CdTe Solar Cells: Cooperative Research and Development (Final Report)

This CRADA will focus on processing, advanced characterization, and testing of photovoltaic materials and devices to understand and improve REEL CdTe solar technology. This will include examining process variations and different buffer, absorber, and contact layers from REEL and NLR to maximize performance. The unique and diverse advanced characterization tools at NLR, such as time-resolved photoluminescence, capacitance-voltage measurements, electron beam scattered diffraction, cathodoluminescence, electron microscopy, TOF-SIMS, and other measurements will be applied to characterize REEL processing to improve understanding and guide experimental directions. Accelerated stability and potential induced degradation tests will be used to analyze metastability, short-and-long term degradation, and improve bankability. A second and major thrust this period will be joint development of Si/CdTe tandem solar cells to overcome industry wide terrestrial solar efficiency limits with the two lowest cost and manufacturable solar materials today. This will include developing novel transparent back contacts that can be incorporated into tandem structures and other novel solar applications, detailed analysis of designs and configurations for CdTe/Si tandem modules, and prototyping REEL CdTe Technology with Si bottom cells in tandem structures.

14 SOLAR ENERGY↗
DOE OSTI2021

The Surge of Metal–Organic-Framework (MOFs)-Based Electrodes as Key Elements in Electrochemically Driven Processes for the Environment

Metal–organic-frameworks (MOFs) are emerging materials used in the environmental electrochemistry community for Faradaic and non-Faradaic water remediation technologies. It has been concluded that MOF-based materials show improvement in performance compared to traditional (non-)faradaic materials. In particular, this review outlines MOF synthesis and their application in the fields of electron- and photoelectron-Fenton degradation reactions, photoelectrocatalytic degradations, and capacitive deionization physical separations. This work overviews the main electrode materials used for the different environmental remediation processes, discusses the main performance enhancements achieved via the utilization of MOFs compared to traditional materials, and provides perspective and insights for the further development of the utilization of MOF-derived materials in electrified water treatment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1995

Wideband fixed-tuned SIS receiver for 200-GHz operation

We report on the design and development of a heterodyne receiver, designed to cover the frequency range 176-256 GHz. This receiver incorporates a niobium superconductor-insulator-superconductor (SIS) tunnel junction mixer, which, chiefly for reasons of reliability and ease of operation, is a fixed-tuned waveguide design. On-chip tuning is provided to resonate out the junction's geometric capacitance and produce a good match to the waveguide circuit. Laboratory measurements on the first test receiver indicate that the required input bandwidth (about 40%) is achieved with an average receiver noise temperature of below 50 K. Mixer conversion gain is observed at some frequencies, and the lowest measured receiver noise is less than 30 K. Furthermore, the SIS mixer used in this receiver is of simple construction, is easy to assemble and is therefore a good candidate for duplication.

RECEIVER NOISE TEMPERATURE↗