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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Lead sulfide - Silicon MOSFET infrared focal plane development

A process for directly integrating photoconductive lead sulfide (PbS) infrared detector material with silicon MOS integrated circuits has been developed primarily for application in long (greater than 10,000 detector elements) linear arrays for pushbroom scanning applications. The processing technology is based on the conventional PMOS and CMOS technologies with a variation in the metallization. Results and measurements on a fully integrated eight-element multiplexer are shown.

Barrett, J. R.↗
NASA NTRS1977

Photo sensor array technology development

The development of an improved capability photo sensor array imager for use in a Viking '75 type facsimile camera is presented. This imager consists of silicon photodiodes and lead sulfide detectors to cover a spectral range from 0.4 to 2.7 microns. An optical design specifying filter configurations and convergence angles is described. Three electronics design approaches: AC-chopped light, DC-dual detector, and DC-single detector, are investigated. Experimental and calculated results are compared whenever possible using breadboard testing and tolerance analysis techniques. Results show that any design used must be forgiving of the relative instability of lead sulfide detectors. A final design using lead sulfide detectors and associated electronics is implemented by fabrication of a hybrid prototype device. Test results of this device show a good agreement with calculated values.

Rossman, M. W.↗
NASA NTRS1983

The application of remote sensing in geobotanical exploration for metal sulfides

A field study was conducted in Mineral, VA in 1980-82 to test the suitability of remote sensing techniques for geobotanical exploration. It was found that on trees growing over lead sulfide deposits, buds opened later and leaves were smaller than on trees growing on soils with background levels of lead and copper. This difference in leaf growth could be detected in remotely sensed data. In the spring, the smaller leaf size of metal-stressed trees resulted in a greater contribution from the soil and bark to the total reflectance imaged by the sensor. In the fall, the leaves of metal-stressed oaks sensed earlier than surrounding vegetation, which was also detected in remotely sensed data. It is concluded that vegetation growing on lead sulfide deposits has a shorter growing season than surrounding vegetation on unmineralized soil and that remotely sensed data collected at either end of the growing season can be used to locate geobotanical anomalies associated with these deposits.

Masuoka, E. J.↗
NASA NTRS1987

Method of fabricating a PbS-PbSe IR detector array

A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chiping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

Barrett, John R.↗
NASA NTRS1986

PbS-PbSe IR detector arrays

A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chipping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

Barrett, John R.↗
NASA NTRS1982

A monolithic lead sulfide-silicon MOS integrated-circuit structure

A technique is developed for directly integrating infrared photoconductive PbS detector material with MOS transistors. A layer of chromium, instead of aluminum, is deposited followed by a gold deposition in order to ensure device survival during the chemical deposition of the PbS. Among other devices, a structure was fabricated and evaluated in which the PbS was directly coupled to the gate of a PMOS. The external bias, load, and source resistors were connected and the circuit was operated as a source-follower amplifier. Radiometric evaluations were performed on a variety of different MOSFETs of different geometry. In addition, various detector elements were simultaneously fabricated to demonstrate small element capability, and it was shown that elements of 25 x 25 microns could easily be fabricated. Results of room temperature evaluations using a filtered 700 K black body source yielded a detectivity at peak wavelength of 10 to the 11th cm (root Hz)/W at 100 Hz chopping frequency.

Jhabvala, M. D.↗
NASA NTRS1986

Growth of lead tin telluride crystals in gels

Improved gels and several geometries were investigated for use in growing crystals. The use of lead sulfide test crystals proved workable, but it was impossible to obtain and maintain a sufficiently concentrated telluride ion solution to successfully grow lead telluride crystals. It appears that oxygen in the solution is capable of oxidizing the telluride ion up to tellurium metal. The method may still be successful, but only if precautions are taken to eliminate dissolved oxygen from the gels and aqueous solutions and to maintain a suitable concentration of telluride, Te(2)-(aq.).

Barber, Patrick G.↗
NASA NTRS2008

Comparison of Carbon XANES Spectra from an Iron Sulfide from Comet Wild 2 with an Iron Sulfide Interplanetary Dust Particle

Among one of the first particles removed from the aerogel collector from the Stardust sample return mission was an approx. 5 micron sized iron sulfide. The majority of the spectra from 5 different sections of this particle suggests the presence of aliphatic compounds. Due to the heat of capture in the aerogel we initially assumed these aliphatic compounds were not cometary but after comparing these results to a heated iron sulfide interplanetary dust particle (IDP) we believe our initial interpretation of these spectra was not correct. It has been suggested that ice coating on iron sulfides leads to aqueous alteration in IDP clusters which can then lead to the formation of complex organic compounds from unprocessed organics in the IDPs similar to unprocessed organics found in comets [1]. Iron sulfides have been demonstrated to not only transform halogenated aliphatic hydrocarbons but also enhance the bonding of rubber to steel [2,3]. Bromfield and Coville (1997) demonstrated using Xray photoelectron spectroscopy that "the surface enhancement of segregated sulfur to the surface of sulfided precipitated iron catalysts facilitates the formation of a low-dimensional structure of extraordinary properties" [4]. It may be that the iron sulfide acts in some way to protect aliphatic compounds from alteration due to heat.

Wirick, S.↗
NASA NTRS1973

Interpretation of the Jupiter red spot. I.

The LPL research programs on Jupiter include continuing photographic coverage of the planet in color and in several wavelength bands; IR image scans especially around 5 microns; medium and high-resolution spectral studies in the photographic and the lead-sulfide regions, with laboratory comparisons; photometric and polarimetric studies; far-IR measurements at high altitudes; chemical studies designed to match formation of Jovian cloud particles; and participation in the NASA Pioneer missions. Some preliminary interpretative remarks are given which are in part suggested by the remarkable IR spectra and IR images of the earth and Mars obtained at NASA-Goddard. This leads to a discussion of the Red Spot and the White Ovals.

Kuiper, G. P.↗
NASA NTRS1972

First spectra of chlorine, bromine, and iodine in the 1.8- to 4.0-micron region.

Use of liquid-nitrogen-cooled lead sulfide detectors to extend observations of the first spectra of the halogens in the infrared region as far as 4.0 microns. Descriptions, comprising wavelengths, wave numbers, intensities, and classifications, are presented that serve to close the gap between the upper wavelength limit of the detailed published analyses of these spectra at about 2.5 microns and the groups of recently classified lines near 4 microns, and also to report newly observed lines in the 1.8- to 2.5-micron region made accessible by detectors of improved response characteristics. Listed wavelengths of observed and identified lines are calculated from established values of the energy levels. The descriptions should facilitate the identification of halogen lines in mixed spectra excited in electrodeless tubes containing halogen compounds.

Humphreys, C. J.↗