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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Chemistry of MOS-LSI radiation hardening

The objective of this task was to obtain chemical information on MOS test samples. Toward this end, high resolution X-ray photoemission spectroscopy (XPS) has been the primary techniques used to characterize the chemistry and structure of the SiO2/Si interface for a variety of MOS structures with differing degrees of susceptibility to damage by ionizing radiation. The major accomplishments of this program are: (1) the identification of a structurally distinct region of SiO2 in the near-interfacial region of thermal SiO2 on Si; (2) the identification in the near-interfacial region of SiO2 structural differences between radiation hard and soft gate oxides; (3) the direct observation of radiation-induced damage sites in thermal SiO2 with XPS using in situ electron stress; (4) the correlation of suboxide state distributions at the SiO2/Si interface with processing parameters and radiation susceptibility; (5) the development of a chemical mechanism for radiation-induced interface state generation in SiO2/Si structures; and (6) the development benign chemical profiling techniques which permit the investigation of oxide/semiconductor structures using surface sensitive electron spectroscopic techniques.

Grunthaner, P.↗
NASA NTRS1993

A vacuum (10 exp -9 torr) friction apparatus for determining friction and endurance life of MoS(x) films

An ultrahigh-vacuum tribometer for use in a ball-on-disk configuration was specially designed for measuring the friction and endurance life of magnetron-sputtered solid lubricating MoS(x) films deposited on sputter-cleaned 400 C stainless-steel disks, when slid against a 6-mm-diameter 440 C stainless-steel ball. The results of tests showed that the tribometer performs satisfactorily in unidirectional rotation in vacuum at a pressure of 10 exp -7 Pa, 10 exp -9 torr. Similarities are observed in the life cycle friction behavior and the coefficient of friction as a function of the number of disk revolutions, for MoS(x) films at average Hertzian contact from 0.33 to 0.69 GPa.

Miyoshi, Kazuhisa↗
NASA NTRS1990

High frequency integrated MOS filters

Several techniques exist for implementing integrated MOS filters. These techniques fit into the general categories of sampled and tuned continuous-time filters. Advantages and limitations of each approach are discussed. This paper focuses primarily on the high frequency capabilities of MOS integrated filters.

Peterson, C.↗
NASA NTRS1993

A MOS for all seasons

From a systems perspective, this paper examines the challenges of a single system to support multiple JPL space exploration missions and the need for unitary responsibility for the system. The focus is a Mission Operations System (MOS), which is effectively a mission management organization with direct authority over data system operations, command sequencing, flight operations control, data management, trajectory determination, telemetry and data acquisition, and spacecraft analysis. Stratagems for training and the approach to processes, procedures, and interfaces to facilitate the transition from the present situation to a truly multimission operational environment are developed. The outcome is a paradigm for a MOS that is achievable, that can effectively support multiple projects, and that can take advantage of technological changes without perturbing the entire system.

Bryant, Larry↗
NASA NTRS2000

Efficient Multi-Dimensional Simulation of Quantum Confinement Effects in Advanced MOS Devices

We investigate the density-gradient (DG) transport model for efficient multi-dimensional simulation of quantum confinement effects in advanced MOS devices. The formulation of the DG model is described as a quantum correction to the classical drift-diffusion model. Quantum confinement effects are shown to be significant in sub-100nm MOSFETs. In thin-oxide MOS capacitors, quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion or quantum effects in simulations dramatically improves the match between C-V simulations and measurements for oxide thickness down to 2 nm. Significant quantum corrections also occur in the I-V characteristics of short-channel (30 to 100 nm) n-MOSFETs, with current drive reduced by up to 70%. This effect is shown to result from reduced inversion charge due to quantum confinement of electrons in the channel. Also, subthreshold slope is degraded by 15 to 20 mV/decade with the inclusion of quantum effects via the density-gradient model, and short channel effects (in particular, drain-induced barrier lowering) are noticeably increased.

Biegel, Bryan A.↗
NASA NTRS2000

Efficient Multi-Dimensional Simulation of Quantum Confinement Effects in Advanced MOS Devices

We investigate the density-gradient (DG) transport model for efficient multi-dimensional simulation of quantum confinement effects in advanced MOS devices. The formulation of the DG model is described as a quantum correction ot the classical drift-diffusion model. Quantum confinement effects are shown to be significant in sub-100nm MOSFETs. In thin-oxide MOS capacitors, quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion of quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion of quantum effects in simulations dramatically improves the match between C-V simulations and measurements for oxide thickness down to 2 nm. Significant quantum corrections also occur in the I-V characteristics of short-channel (30 to 100 nm) n-MOSFETs, with current drive reduced by up to 70%. This effect is shown to result from reduced inversion charge due to quantum confinement of electrons in the channel. Also, subthreshold slope is degraded by 15 to 20 mV/decade with the inclusion of quantum effects via the density-gradient model, and short channel effects (in particular, drain-induced barrier lowering) are noticeably increased.

Biegel, Bryan A.↗
NASA NTRS2003

MOS Circuitry Would Detect Low-Energy Charged Particles

Metal oxide semiconductor (MOS) circuits for measuring spatially varying intensities of beams of low-energy charged particles have been developed. These circuits are intended especially for use in measuring fluxes of ions with spatial resolution along the focal planes of mass spectrometers. Unlike prior mass spectrometer focal-plane detectors, these MOS circuits would not be based on ion-induced generation of electrons, and photons; instead, they would be based on direct detection of the electric charges of the ions. Hence, there would be no need for microchannel plates (for ion-to-electron conversion), phosphors (for electron-to-photon conversion), and photodetectors (for final detection) -- components that degrade spatial resolution and contribute to complexity and size. The developmental circuits are based on linear arrays of charge-coupled devices (CCDs) with associated readout circuitry (see figure). They resemble linear CCD photodetector arrays, except that instead of a photodetector, each pixel contains a capacitive charge sensor. The capacitor in each sensor comprises two electrodes (typically made of aluminum) separated by a layer of insulating material. The exposed electrode captures ions and accumulates their electric charges during signal-integration periods.

Sinha, Mahadeva↗
DOE OSTI2025

Focused Helium Ion Beam for Direct Patterning of Monolayer MoS 2 Nanoribbon Field Effect Devices

The helium ion microscope (HIM) focused ion beam (FIB) has emerged as a powerful tool to directly pattern nanostructures below 10 nm due to its high-resolution capabilities and the inert nature of the ion source. These attributes make HIM FIB particularly interesting for patterning 2D materials such as transition metal dichalcogenides (TMDs) to investigate transport phenomena at the nanoscale. Reported here is the fabrication of MoS 2 nanoribbon devices using HIM FIB-induced etching (FIBIE) with XeF 2 , allowing for reduced ion dose compared to direct sputtering. While patterning is efficacious, the devices exhibit performance degradation with decreasing nanoribbon width due to damage up to 150 nm beyond the patterned edge. Incorporating an hBN encapsulation improves device performance by one order of magnitude, although the lateral extent of damage remains unchanged. The spatial distribution of damage is shown to be determined by the forward- and backscattered ions and electrons, while the hBN encapsulation layer substantially reduces damage from XeF 2 interactions in unexposed regions. Raman and photoluminescence (PL) measurements corroborate these findings, while ion/solid interaction simulations further elucidate the resolution limits imposed by substrate interactions. In conclusion, this work provides critical insights and a practical pathway for utilizing HIM FIBIE in 2D TMD functional device patterning.

MoS 2↗
DOE OSTI2020

Materials Data on Sb(MoS)2 by Materials Project

Sb(MoS)2 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Mo+3.50+ sites. In the first Mo+3.50+ site, Mo+3.50+ is bonded in a 6-coordinate geometry to two equivalent Sb3- and four S2- atoms. Both Mo–Sb bond lengths are 2.91 Å. There are a spread of Mo–S bond distances ranging from 2.37–2.61 Å. In the second Mo+3.50+ site, Mo+3.50+ is bonded in a 3-coordinate geometry to three equivalent Sb3- and three equivalent S2- atoms. There are one shorter (2.88 Å) and two longer (2.92 Å) Mo–Sb bond lengths. There are two shorter (2.37 Å) and one longer (2.39 Å) Mo–S bond lengths. Sb3- is bonded in a 5-coordinate geometry to five Mo+3.50+ atoms. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Mo+3.50+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to four Mo+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs(MoS)3 by Materials Project

Cs(MoS)3 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Cs is bonded in a 9-coordinate geometry to nine equivalent S atoms. There are three shorter (3.64 Å) and six longer (3.78 Å) Cs–S bond lengths. Mo is bonded in a distorted see-saw-like geometry to four equivalent S atoms. There are a spread of Mo–S bond distances ranging from 2.49–2.60 Å. S is bonded in a 7-coordinate geometry to three equivalent Cs and four equivalent Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoS)3 by Materials Project

K(MoS)3 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. K is bonded in a 9-coordinate geometry to nine equivalent S atoms. There are six shorter (3.48 Å) and three longer (3.52 Å) K–S bond lengths. Mo is bonded in a distorted see-saw-like geometry to four equivalent S atoms. There are a spread of Mo–S bond distances ranging from 2.49–2.60 Å. S is bonded in a 7-coordinate geometry to three equivalent K and four equivalent Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(MoS)3 by Materials Project

Rb(MoS)3 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Rb is bonded in a 9-coordinate geometry to nine equivalent S atoms. There are three shorter (3.57 Å) and six longer (3.61 Å) Rb–S bond lengths. Mo is bonded in a distorted see-saw-like geometry to four equivalent S atoms. There are a spread of Mo–S bond distances ranging from 2.49–2.60 Å. S is bonded in a 7-coordinate geometry to three equivalent Rb and four equivalent Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoS)3 by Materials Project

K(MoS)3 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. K is bonded in a trigonal planar geometry to three equivalent S atoms. All K–S bond lengths are 3.11 Å. Mo is bonded in a distorted see-saw-like geometry to four equivalent S atoms. There are a spread of Mo–S bond distances ranging from 2.49–2.60 Å. S is bonded in a 5-coordinate geometry to one K and four equivalent Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoS)9 by Materials Project

K(MoS)9 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. K is bonded in a 9-coordinate geometry to nine S atoms. There are three shorter (3.42 Å) and six longer (3.44 Å) K–S bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a distorted see-saw-like geometry to four S atoms. There are a spread of Mo–S bond distances ranging from 2.49–2.55 Å. In the second Mo site, Mo is bonded in a distorted see-saw-like geometry to four S atoms. There are a spread of Mo–S bond distances ranging from 2.49–2.55 Å. There are two inequivalent S sites. In the first S site, S is bonded in a distorted pentagonal planar geometry to one K and four Mo atoms. In the second S site, S is bonded in a distorted pentagonal planar geometry to one K and four Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(MoS)9 by Materials Project

Rb(MoS)9 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Rb is bonded in a 9-coordinate geometry to nine S atoms. There are three shorter (3.44 Å) and six longer (3.53 Å) Rb–S bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a distorted see-saw-like geometry to four S atoms. There are a spread of Mo–S bond distances ranging from 2.50–2.55 Å. In the second Mo site, Mo is bonded in a distorted see-saw-like geometry to four S atoms. There are a spread of Mo–S bond distances ranging from 2.50–2.55 Å. There are two inequivalent S sites. In the first S site, S is bonded in a distorted pentagonal planar geometry to one Rb and four Mo atoms. In the second S site, S is bonded in a distorted pentagonal planar geometry to one Rb and four Mo atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs(MoS)9 by Materials Project

Cs(MoS)9 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Cs is bonded in a 9-coordinate geometry to nine S atoms. There are three shorter (3.65 Å) and six longer (3.68 Å) Cs–S bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a distorted see-saw-like geometry to four S atoms. There are a spread of Mo–S bond distances ranging from 2.50–2.55 Å. In the second Mo site, Mo is bonded in a distorted see-saw-like geometry to four S atoms. There are two shorter (2.50 Å) and two longer (2.54 Å) Mo–S bond lengths. There are two inequivalent S sites. In the first S site, S is bonded in a 5-coordinate geometry to one Cs and four Mo atoms. In the second S site, S is bonded in a distorted pentagonal planar geometry to one Cs and four Mo atoms.

36 MATERIALS SCIENCE↗
NASA NTRS2023

Ionizing Radiation Effects on Hole Collection Backside-Illuminated P-Type Deep-Trench Pinned Photo-MOS Pixels under Image Acquisition

Dark current degradation, origins, and annealing behavior after x-ray irradiation are studied in a P-type, hole collecting, backside-illuminated image sensor currently being developed at STMicroelectronics and based on deep-trenched photo-MOS pixels. Different biasing conditions during irradiation, i.e. grounded or biased and sequenced, are compared. The dark current increase with total ionizing dose (TID) and the dark current annealing behavior seem to be driven by the backside interface between the P-epitaxy of the pixels and the ONO stack. Despite still being under development, this pixel architecture already exhibits both very good electro-optical performance and a better radiation hardness than pinned photodiode-based CMOS Image sensors that benefit from the same advanced CIS processing technologies. At high total dose range, the photogate challenges custom Radiation-Hardened-by-Design photodiodes by exhibiting a comparable radiation tolerance while bringing new features such as high-resolution or Correlated Double Sampling.

CMOS Image Sensor (CIS)↗
DOE OSTI2023

On the Interplay between Size and Disorder in Suppressing Intercalation-Induced Phase Transitions in Pseudocapacitive Nanostructured MoS 2

Pseudocapacitors are an emerging class of energy storage materials that offer an attractive compromise between the energy density of batteries and power density of electric double-layer capacitors. Decreasing particle size and increasing surface area of battery materials is a common approach for introducing pseudocapacitive behavior and increasing power density. However, in many cases, as the crystal size is reduced, lattice disorder of unknown extent is also introduced, making it difficult to characterize the relative contribution of size and disorder to fast-charging performance. Here, in this work, a series of nanostructured MoS 2 materials are synthesized with different crystallite sizes and degrees of crystallinity to decouple the effects of size and disorder on charge/discharge kinetics. The extent and type of disorder in each material is quantified by total X-ray scattering experiments and pair distribution function analyses. Electrochemical characterization, including galvanostatic rate capability, cyclic voltammetry, and various kinetic analyses, are used to demonstrate that both decreasing particle size and introducing lattice disorder are effective strategies for increasing charge storage kinetics, and that the effects are additive. Finally, operando X-ray diffraction measurements show that both size and disorder can be used suppress first-order Li + intercalation-induced phase transitions, a key feature for enabling pseudocapacitive charge storage.

36 MATERIALS SCIENCE↗