Isotope effect for electron mobility in anthracene
Transient photoconductivity measurements of room temperature electron mobility in deuterated anthracene single crystals, discussing isotope effect
Hermann, A. M.↗
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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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An optical quality meter suitable for cryogenic liquids
Construction of instrument to measure ratio of liquid to gas of flowing transparent cryogenic fluid is described. Instrument consists of collimated light source and photoconductive cell. Operation of instrument is described and illustration of equipment is provided.
Hobart, H. F.↗
High field CdS detector for infrared radiation
New and highly sensitive method of detecting infrared irradiation makes possible solid state infrared detector which is more sensitive near room temperature than usual photoconductive low band gap semiconductor devices. Reconfiguration of high field domains in cadmium sulphide crystals provides basis for discovery.
Tyagi, R. C.↗
Silicon solar cells as a high-solar-intensity radiometer
The characteristics of a conventional, 1- by 2-cm, N/P, gridded silicon solar cell when used as a radiometer have been determined for solar intensity levels to 2800 mW/sq cm (20 solar constants). The short-circuit current was proportional to the radiant intensity for levels only to 700 mW/sq cm (5 solar constants). For intensity levels greater than 700 mW/sq cm, it was necessary to operate the cell in a photoconductive mode in order to obtain a linear relation between the measured current and the radiant intensity. When the solar cell was biased with a reverse voltage of -1 V, the measured current and radiant intensity were linearly related over the complete intensity range from 100 to 2800 mW/sq cm.
Spisz, E. W.↗
A space simulation test chamber development for the investigation of radiometric properties of materials
The design, fabrication, and preliminary utilization of a thermal vacuum space simulation facility are discussed. The facility was required to perform studies on the thermal radiation properties of materials. A test chamber was designed to provide high pumping speed, low pressure, a low photon level radiation background (via high emissivity, coated, finned cryopanels), internal heat sources for rapid warmup, and rotary and linear motion of the irradiated materials specimen. The radiation detection system consists of two wideband infrared photoconductive detectors, their cryogenic coolers, a cryogenic-cooled blackbody source, and a cryogenic-cooled optical radiation modulator.
Enlow, D. L.↗
Electron-beam-deposited thin polymer films - Electrical properties vs bombarding current.
Polymer films about 150 A thick, deposited on glass substrates by electron bombardment of tetramethyltetraphenyltrisiloxane, were studied, after being sandwiched between evaporated aluminum electrodes, the top one semitransparent. The capacitance, conductance, and photoconductance of the sandwiches were measured at room temperature as a function of the electron bombarding current which formed the polymer. The polymer thickness was obtained independently from Christy's (1960) empirical formula for the rate of formation. The obtained results indicate that, with increasing bombarding current, the polymer undergoes an increase in both crosslinking bonds and dangling bonds. Exposure to air drastically reduces the density of dangling bonds, but does not affect the crosslinking.
Babcock, L. E.↗
N-type mercury-cadmium-telluride photoconductors in optical heterodyne communication systems.
Discussion of the performance of a photoconductive (Hg,Cd)Te detector/mixer in a carbon dioxide laser heterodyne communication system. The utility of computer simulation of the performance of an optical heterodyne detector/mixer is demonstrated. Certain unusual properties of this device are pointed out that, while having a substantial impact on device performance, have received little previous attention.
Cohen, S. C.↗
Performance of S-192 /Hg,Cd/Te arrays.
Very high performance (Hg,Cd)Te photoconductive detectors have been fabricated for use on the S-192 experiment, which is a multispectral scanner being built by Honeywell for the NASA Manned Space Center's Skylab. The S-192 will scan the earth from Skylab and record data in twelve near infrared spectral bands and one long wavelength band. These detectors demonstrate good uniformity in performance across an array. State-of-the-art fabrication techniques have been used to make detectors with good definition that are 5-10 microns thick with 25-micron spacing between elements.
Aldrich, N. C.↗
N-Color /Hg,Cd/Te photodetectors.
N-color (Hg,Cd)Te photodetectors capable of spectral band analysis have been fabricated, tested, and delivered. This paper discusses the state of the art in (Hg,Cd)Te n-color photoconductive detectors. Included is a discussion of narrow band two-color devices responsive in the region of 8-14 microns. Preliminary results are also included for a unique three-color (Hg,Cd)Te device with cutoff wavelengths of 9.1, 10.8, and 13.8 microns.
Halpert, H.↗
Combined sun-acquisition and sun gate-sensor system for spacecraft attitude control
Arrangement combines acquisition and gate functions and reduces sensitivity so that attitude control is effective regardless of changes in solar intensity. There are five photoconductive detectors all electrically interconnected. Detectors are so positioned that, regardless of spacecraft orientation at any instant of interest, at least one detector is illuminated.
Schmidt, L. F.↗
High sensitivity infrared 10.6 micrometer heterodyne receiver development
The results are presented for a study on the design of an infrared 10.6-micrometer quantum-noise-limited optical receiver subsystem. Performance measurements of the HgCdTe photomixer preamplifier combination were carried out for photomixer temperatures up to 152 K and a photomixer frequency response of up to 420 MHz was obtained. Results of temperature and bias cycling of HgCdTe photomixers are reported. Design considerations for an operational 10.6 micrometer heterodyne receiver are presented. These consist of design data on required laser LO illumination, heat load levels for photomixer cooler, photomixer uniformity and the effects of photomixer impedance match on receiver sensitivity. Analysis and measurements of 10.6 micrometer heterodyne detection in an extrinsic photoconductive (p-type) HgCdTe photomixer are also presented.
Source record↗
Methods of measurement for semiconductor materials, process control, and devices
This progress report describes NBS activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices. Significant accomplishments during this reporting period include design of a plan to provide standard silicon wafers for four-probe resistivity measurements for the industry, publication of a summary report on the photoconductive decay method for measuring carrier lifetime, publication of a comprehensive review of the field of wire bond fabrication and testing, and successful completion of organizational activity leading to the establishment of a new group on quality and hardness assurance in ASTM Committee F-1 on Electronics. Work is continuing on measurement of resistivity of semiconductor crystals; characterization of generation-recombination-trapping centers in silicon; study of gold-doped silicon; development of the infrared response technique; evaluation of wire bonds and die attachment; and measurement of thermal properties of semiconductor devices, delay time and related carrier transport properties in junction devices, and noise properties of microwave diodes.
Bullis, W. M.↗
Photoconductor-metal contact at higher densities.
The formation of space charge in the barrier region is discussed. This region extends to a distance, x-sub o, equal to 200 A plus twice the mean free path of majority carriers. The conventional transport equation can be used only for x greater than x-sub o, and the carrier density at x-sub o represents a boundary condition for the bulk. Its change as a function of applied voltage, temperature, and light intensity in photoconducting CdS is discussed. The time dependence of the space-charge formation in the region between 0 and x-sub o is analyzed. It is shown under which conditions the individuality of the metal contact is observable.
Dussel, G. A.↗
Specific wavelength colorimeter
A self contained, specific wavelength, single beam colorimeter is described for direct spectrophotometric measurement of the concentration of a given solute in a test sample. An electrical circuit employing a photoconductive cell converts the optical output into a linear, directly readable meter output. The colorimeter is simple to operate and is adapted for use in zero gravity conditions. In a specific application, the colorimeter is designed to analyze the concentration of iodine in potable water carried aboard a space vehicle such as the 4B stage of Skylab.
Brawner, C. C.↗
Real-time incoherent-to-coherent optical converter
Description of a real-time incoherent-to-coherent optical converter designed for application in image processing systems. The converter utilizes the photoconductivity effect of the compound Bi(12)SiO(20) for spatial modulation of electrical polarization in the compound. An optically absorbed write-in image is stored as an image polarization pattern in the device. Readout is effectuated electrooptically by using phase retardation in a polarized coherent light beam during the passage through the crystal. The operating mode required for achieving continuous image conversion with a high-speed recyclability is discussed. The performance characteristics of the converter are given and the fabrication technology is described.
Vohl, P.↗
Read-only optical storage medium
Photosensitive recording medium consists of thin-film silicone resin deposited on photoconductive substrate. Medium is useful for holographic interferometry studies.
Gange, R. A.↗
LK21T1 S/N V-3 infrared detector
An infrared detector was fabricated to determine the feasibility of atmospheric sounding from synchronous orbit for water vapor and carbon dioxide. The device was extensively tested both before and after a 24-hour soak at 50 C and relative humidity of 95 percent. No degradation in performance as a result of the soak was observed. The device contains a single photoconductive HgCdTe element designed to operate in the six to fifteen micron region.
Source record↗
Detection of the O III 88.16-micron forbidden line in M17
This paper reports the detection of the fine-structure forbidden line of O III at 88.16 microns in emission from M 17 (the Omega Nebula), which is an optically bright galactic H II region and a strong thermal radio source. The observations were made using an airborne 30-cm telescope and a liquid helium-cooled grating spectrometer with Ge:Ga photoconductive detectors. The line intensity is found to be 2.2 (+1.0, -0.7) by 10 to the -15th power W/sq cm. The results are compared with those of a search for the present line in M 42 as well as with theoretical predictions of the line intensity.
Ward, D. B.↗