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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Tailorable Doping-Spike PtSi Infrared Detectors Fabricated by Si Molecular Beam Epitaxy

By incorporating a 1-nm-thick p+ doping spike at the PtSi/Si interface, we have successfullydemonstrated extended cutoff wavelengths of PtSi Schottky infrared detectors. The extended cutoffwavelengths resulted from the reduced effective potential barriers due to the combined effects of anincreased electric field near the silicide/Si interface and the Schottky image force. The p+ dopingspikes were grown by molecular beam epitaxy at 450 degrees C using elemental boron as the dopantsource, with doping concentrations ranging from 5 x 10^(19) to 2 x 10^(20) cm^(-3). The cutoffwavelengths were shown to increase with increasing doping concentrations of the p+ spikes. Thermionic emission dark current characteristics were observed and photoresponse in the LWIRregime was demonstrated. Furthermore, the effective potential barriers determined by the Richardsonplots were used to study the electrically activated boron dopant concentrations of the thin (1-nm-thick) spikes.

del Castillo, H. M.↗
NASA NTRS2019

Improving the longest SI traceable hyperspectral infrared record from space from the AIRS

The Atmospheric Infrared Sounder (AIRS) is a “facility” instrument developed by NASA as an experimental demonstration of advanced technology for remote sensing and the benefits of high resolution infrared spectra to weather forecasting and science investigations . It was launched into a 1:30 am/pm polar orbit on May 4, 2002 on the EOS Aqua Spacecraft, and is expected to provide highly calibrated data beyond 2024. AIRS has 2378 infrared channels ranging from 3.7 um to 15.4 um and a 13.5 km footprint. The AIRS data are used for weather forecasting, climate process studies and validating climate models. AIRS is a vital IR reference sensor for GSICS and is used by JMA for comparison to Himawari AHI , KMA for comparison to COMS , NOAA for comparison to CrIS and GOES , and EUMETSAT for comparison to IASI .

Strow, Larrabee↗
NASA NTRSDate not supplied

Cold Conditions Promote Mg and Si Incorporation in Fe/Si-Rich and Al-Poor X-Ray Amorphous Material in Mars-Relevant Field Environments

X-ray amorphous material that is variably Fe/Si-rich, Al-poor, and volatile containing is prevalent (~15-73 wt.%) within ancient fluvial-lacustrine and eolian sediments examined by the CheMin instrument in Gale crater. Al-rich X-ray amorphous material within Mars-analog environments on Earth has previously been proposed to result from aqueous alteration under cold and icy conditions. However, to the best of our knowledge, no work to date has examined the effects of climate upon the formation of Al-poor and Fe/Si-rich X-ray amorphous material. This study therefore investigates the production of Al-poor and Fe-containing X-ray amorphous material and the chemical heterogeneity within that material under varying temperature conditions to better interpret the formation of Fe-containing X-ray amorphous material detected on Mars.

A D Feldman↗
NASA NTRSDate not supplied

Foreign Object Damage in Yb 2 Si 2 O 7 Environmental Barrier Coatings

Environmental Barrier Coatings (EBCs) have been developed as an enabling technology for silicon carbide based ceramic matrix composites in gas turbine engines. Two of the key failure mechanisms identified in EBC systems are foreign object damage (FOD) and the oxidative growth of a SiO 2 thermally grown oxide (TGO) layer that can lead to premature coating spallation. Previously the effects of FOD on NASA’s second generation Ytterbium Disilicate EBC were studied and recently it was shown that the addition of oxide modifiers resulted in improved oxidation resistance in the EBC. This work will compare FOD of the baseline Ytterbium Disilicate EBC to the that of the modified EBC. FOD was performed at room temperature using a 1.59 mm hardened steel ball with projectile velocities of 50-300 m/s. Additionally, the effects of oxidation via cyclic steam exposure prior to impact were investigated.

environmental barrier coatings (EBCs)↗
NASA NTRS2023

Total Ionizing Dose Test Report Microchip JANTXV2N6284 NPN Darlington Power Si Transistor

This study was undertaken to determine the effects of total ionizing dose (TID) on the JANTXV2N6284 NPN Darlington power bipolar junction transistor (BJT). The device was parametrically characterized prior to, at each incremental dose step, and after irradiation. Testing was at a low-dose rate using the NASA GSFC Radiation Effects Facility (REF).

Kaitlyn L Ryder↗