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Results for “electrical characterization”

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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

On-orbit characterization of electric propulsion on LEO satellites

Utilizing commercial or military satellites as testbeds for subsystems is a potential platform for small devices. Electric propulsion is a viable and upcoming subsystem that is of high interest to planetary mission engineers as well as commercial satellite developers. It is proposed that by incorporating small lightweight electric propulsion devices onto small satellites as external or 'bolt-on' experiments, an increase in the number of flight opportunities can occur. Specific problems are spacecraft body interaction, contamination effects, thermal interface problems, power conditioning control electronics, and propulsion feed system interfaces.

Barnhart, D.↗
NASA NTRS1977

JAN transistor and diode characterization test program

A statistical summary of electrical characterization was performed on JAN diodes and transistors. Parameters are presented with test conditions, mean, standard deviation, lowest reading, 10% point, 90% point and highest reading.

Takeda, H.↗
NASA NTRS1975

Study of materials for space processing

Materials were selected for device applications and their commercial use. Experimental arrangements were also made for electrical characterization of single crystals using electrical resistivity and Hall effect measurements. The experimental set-up was tested with some standard samples.

Lal, R. B.↗
DOE OSTI2020

Hall Effect Characterization of α ‐Irradiated p‐Type 4H‐SiC

Most electrical characterization of radiation damage to semiconductors is conducted on full devices or on low‐doped material. However, evaluating the radiation hardness is challenging in less mature semiconductor systems where low‐doped material is unavailable and full devices are difficult to realize. Herein, temperature‐dependent Hall effect measurements are used to demonstrate α particle‐induced radiation effects in p‐type 4H‐SiC with a room temperature hole concentration of . The 4H‐SiC is irradiated by α particles from a 210 Po source over a fluence of –. Modeling the hole concentration as a function of temperature shows that α radiation causes hole compensation through the introduction of hole traps. The radiation also induces a reduction in hole mobility due to an increase in defect‐related scattering centers. At low temperatures and increasingly higher fluences, the conduction mechanism changes from band conduction to another mechanism.

Frye, Clint D.↗
DOE OSTI2021

Low barrier height in a ZnO nanorods/NbSe 2 heterostructure prepared by van der Waals epitaxy

Two-dimensional (2D) materials as contacts for semiconductor devices have attracted much attention due to minimizing Fermi level pinning. Schottky–Mott physics has been widely employed to design 2D material-based electrodes and to elucidate their contact behavior. In this study, we revealed that charge transfer across a 2D/semiconductor heterointerface and materials characteristics besides work function should be accounted for in fabrication of electrodes based on 2D materials. Our density functional theory (DFT) calculations predicted that charge transfer between ZnO and NbSe 2 lowers the barrier height at the heterojunction and that conductive surface states of ZnO provide an additional conduction channel in the ZnO/NbSe 2 heterostructures. Crystalline ZnO/NbSe 2 heterostructures were prepared by the hydrothermal method. Electrical characterizations of the ZnO/NbSe 2 heterostructures showed Ohmic-like behavior as predicted by the DFT calculations, opposed to the prediction based on the Schottky–Mott model.

2D materials↗
DOE OSTI2024

Thermal scanning probe and laser lithography for patterning nanowire based quantum devices

Semiconductor nanowire (NW) quantum devices offer a promising path for the pursuit and investigation of topologically-protected quantum states, and superconducting and spin-based qubits that can be controlled using electric fields. Theoretical investigations into the impact of disorder on the attainment of dependable topological states in semiconducting nanowires with large spin–orbit coupling and g-factor highlight the critical need for improvements in both growth processes and nanofabrication techniques. In this work, we used a hybrid lithography tool for both the high-resolution thermal scanning probe lithography and high-throughput direct laser writing of quantum devices based on thin InSb nanowires with contact spacing of 200 nm. Electrical characterization demonstrates quasi-ballistic transport. The methodology outlined in this study has the potential to reduce the impact of disorder caused by fabrication processes in quantum devices based on 1D semiconductors.

36 MATERIALS SCIENCE↗
NASA NTRS1977

JAN transistor and diode characterization test program, JANTX diode 1N5623

A statistical summary of the electrical characterization of diodes and transistors is presented. Each parameter is presented with test conditions, mean, standard deviation, lowest reading, 10% point (where 10% of all readings are equal to or less than the indicated reading), 90% point (where 90% of all readings are equal to or less than indicated reading) and the highest reading.

Takeda, H.↗
NASA NTRS1987

Growth and characterization of cubic SiC single-crystal films on Si

Morphological and electrical characterization results are presented for cubic SiC films grown by chemical vapor deposition on single-crystal Si substrates. The films, up to 40 microns thick, were characterized by optical microscopy, (SEM), (TEM), electron channeling, surface profilometry, and Hall measurements. A variety of morphological features observed on the SiC films are described. Electrical measurements showed a decrease in the electron mobility with increasing electron carrier concentration, similar to that observed in Si. Room-temperature electron mobilities up to 520 sq cm/V-s (at an electron carrier concentration of 5 x 10 to the 16th/cu cm) were measured. Finally, a number of parameters believed to be important in the growth process were investigated, and some discussion is given of their possible effects on the film characteristics.

Powell, J. Anthony↗
NASA NTRS2011

Characterization of an Autonomous Non-Volatile Ferroelectric Memory Latch

We present the electrical characterization of an autonomous non-volatile ferroelectric memory latch using the principle that when an electric field is applied to a ferroelectriccapacitor,the positive and negative remnant polarization charge states of the capacitor are denoted as either data 0 or data 1. The properties of the ferroelectric material to store an electric polarization in the absence of an electric field make the device non-volatile. Further the memory latch is autonomous as it operates with the ground, power and output node connections, without any externally clocked control line. The unique quality of this latch circuit is that it can be written when powered off. The advantages of this latch over flash memories are: a) It offers unlimited reads/writes b) works on symmetrical read/write cycles. c) The latch is asynchronous. The circuit was initially developed by Radiant Technologies Inc., Albuquerque, New Mexico.

John, Caroline S.↗
DOE OSTI2023

Wafer-Scale Synthesis of 2D Materials by an Amorphous Phase-Mediated Crystallization Approach

The interest in the wafer-scale growth of two-dimensional (2D) materials, including transition metal dichalcogenides (TMDCs), has been rising for transitioning from lab-scale devices to commercial-scale systems. Among various synthesis techniques, physical vapor deposition, such as pulsed laser deposition (PLD), has shown promise for the wafer-scale growth of 2D materials. However, due to the high volatility of chalcogen atoms (e.g., S and Se), films deposited by PLD usually suffer from a lack of stoichiometry and chalcogen deficiency. To mitigate this issue, excess chalcogen is necessary during the deposition, which results in problems like uniformity or not being repeatable. This study demonstrates a condensed-phase or amorphous phase-mediated crystallization (APMC) approach for the wafer-scale synthesis of 2D materials. This method uses a room-temperature PLD process for the deposition and formation of amorphous precursors with controlled thicknesses, followed by a post-deposition crystallization process to convert the amorphous materials to crystalline structures. This approach maintains the stoichiometry of the deposited materials throughout the deposition and crystallization process and enables the large-scale synthesis of crystalline 2D materials (e.g., MoS 2 and WSe 2 ) on Si/SiO 2 substrates, which is critical for future wafer-scale electronics. We show that the thickness of the layers can be digitally controlled by the number of laser pulses during the PLD phase. Optical spectroscopy is used to monitor the crystallization dynamics of amorphous layers as a function of annealing temperature. The crystalline quality, domain sizes, and the number of layers were explored using nanoscale and atomistic characterization (e.g., AFM, STEM, and EDS) along with electrical characterization to explore process–structure–performance relationships. Finally, this growth technique is a promising method that could potentially be adopted in conventional semiconductor industries for wafer-scale manufacturing of next-generation electronic and optoelectronic devices.

2D electronics↗
DOE OSTI2022

Detection of high energy ionizing radiation using deeply depleted graphene–oxide–semiconductor junctions

Graphene’s linear band structure and two-dimensional density of states provide an implicit advantage for sensing charge. Here, these advantages are leveraged in a deeply depleted graphene–oxide–semiconductor (D2GOS) junction detector architecture to sense carriers created by ionizing radiation. Specifically, the room temperature response of a silicon-based D2GOS junction is analyzed during irradiation with 20 MeV Si4+ ions. Detection was demonstrated for doses ranging from 12 to 1200 ions with device functionality maintained with no substantive degradation. To understand the device response, D2GOS pixels were characterized post-irradiation via a combination of electrical characterization, Raman spectroscopy, and photocurrent mapping. This combined characterization methodology underscores the lack of discernible damage caused by irradiation to the graphene while highlighting the nature of interactions between the incident ions and the silicon absorber.

Ruiz, Isaac↗
DOE OSTI2020

Characterization and Analysis of Insulated Metal Substrate-Based SiC Power Module for Traction Application

This paper presents the electrical characterization and drive cycle--based thermal analysis of an insulated metal substrate (IMS)--based silicon carbide power module for high-power traction inverters. The substrate was constructed using a thin layer of polymer--ceramic blend dielectric material with a thick copper core to improve transient thermal performance. The cooling performance of this module has already been validated with promising results. In this paper, an experimental test bed was set up to evaluate the dynamic and static electrical performance of the designed module under a wide range of operating conditions. The characterization results were then used to develop a drive cycle--based thermal model to validate the performance compared to the traditional direct bonded copper--based power module. The results indicate that the IMS-based power module is a suitable solution for high-power traction applications.

Chowdhury, Shajjad↗
DOE OSTI2022

Probing the Contribution of Lateral Pathways to Out–of–Plane Charge Transport in Organic Bulk Heterojunctions

The nanoscale interpenetrating electron donor–acceptor network in organic bulk heterojunction (BHJ) solar cells results in efficient charge photogeneration but creates complex 3D pathways for charge transport. At present, little is known about the extent to which out-of-plane charge flow relies on lateral electrical connectivity. In this work, a procedure, based on conductive atomic force microscopy, is introduced to quantify lateral current spreading during out-of-plane charge transport. Using the developed approach, the dependence of lateral spreading on BHJ phase separation, composition, and molecule type (small molecule vs polymer) is studied. In the small-molecule BHJ, 7,7'-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl)bis(6-fluoro-4-(5'-hexyl-[2,2'-bithiophen]-5-yl)benzo[c]-[1,2,5]thiadiazole):(6,6)-Phenyl-C 71 -butyric acid methyl ester (p-DTS(FBTTh 2 ) 2 :PC 71 BM), an increase is observed in lateral hole current spreading as the population of donor crystallites, bearing an edge-on molecular orientation, is increased. When integrated into BHJs, the polymer donor poly(3-hexylthiophene-2,5-diyl) (P3HT) leads to greater lateral hole current spreading and more spatially uniform charge transport than the small-molecule donor, owing to in-plane charge transport along the polymer backbone. Finally, through the newly introduced electrical characterization scheme, these experiments bring to light the role of lateral electrical connectivity in assisting charge navigation across BHJs.

14 SOLAR ENERGY↗
DOE OSTI2023

Pinhole electrical conductivity in polycrystalline Si on locally etched SiN$_y$/SiO$_x$ passivating contacts for Si solar cells

State-of-the-art monocrystalline Si (c-Si) solar cells require passivating contacts to achieve a high degree of charge-carrier separation and collection. In this work, we focus on boron-doped polycrystalline Si on locally etched silicon nitride/silicon oxide (PLENO) passivating contacts. In PLENO contacts, excellent surface passivation is provided by the ~10 nm dielectric bilayer, while pinholes in the dielectric bilayer, that are filled with doped polycrystalline Si, provide charge-carrier selectivity and transport. During PLENO fabrication, etch undercut in the dielectric bilayer occurs. Here, using electrical characterization and microscopies, we show that undercut causes pinholes to be electrically resistive in PLENO. A processing sequence that eliminates the undercut in the final PLENO structure results in electrically conductive pinholes with low contact resistivity.

14 SOLAR ENERGY↗
DOE OSTI2026

Experimental Characterization and Modeling of High Hole Mobility GeSn Quantum Wells: The Role of Alloy Disorder Scattering

Understanding mechanisms influencing electrical transport in material systems not only provides a scientific explanation for observed behavior but also offers insight into ways to enhance transport in devices. This study reports experimental hole mobility of 8 x 10 4 cm 2 V -1 s -1 in a Ge 0.92 Sn 0.08 , the highest recorded mobility for the GeSn system. A study of the material's quality is presented using structural and electrical characterization techniques, with transport data being supported by simulations using an extensive modeling framework. Quantum Hall measurements further indicate the material's high quality and potential spintronic applications, with extracted values of 0.0689$m$ 0 and 13.6 for the effective mass and effective g‐factor, respectively. It is observed that transport is limited by alloy disorder scattering at cryogenic temperatures. A comparative study between the presented structure and similar quantum well heterostructures revealed that the difference in hole mobilities is captured by a disparity in the reduced nominal alloy disorder scattering potential (Δ U alloy = 0.8 eV), that is lower than the value of a fully random alloy (Δ U alloy = 1.4–1.7 eV) potential. The difference in Δ U alloy suggests that heterostructures with similar geometries and alloy compositions can have different alloy disorder scattering, implying that an underlying mechanism, such as short‐range order, may be responsible and warrants further investigation.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS1984

Stress studies in EFG

Electrical characterization of defects induced in FZ and CZ silicon stress in four-point bending above 1200 C was started. Techniques to study electrical activity that will permit correlation of defect activity with diffusion length and with room and low temperature EBIC are being developed. Preliminary characterization of defects in ribbon grown at very low speeds of less than 1 cm/min shows that the dislocation density is very low over significant regions of cross section, while regions of high dislocation density (approx. 5 x 10(6)/cm(2)) occur in bands in a number of places. Addition measurements of stress distributions in EFG material were obtained at the University of Illinois using shadow-Moire interferometry.

Source record↗