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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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The photoluminescence emission from InGaAs/GaAs quantum-well and quantum-dot (QD) structures are compared after controlled irradiation with 1.5 MeV proton fluxes. Results presented here show a significant enhancement in radiation tolerance with three-dimensional quantum confinement.
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Heavy ion irradiations of two types of commercial DRAMs reveal unexpected angular responses. One device's cross section varied by two orders of magnitude with azimuthal angle. Accurate prediction of space rates requires accommodating this effect.
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Advanced commercial DRAMs are particularly attractive to designers for space applications needing large memory arrays due to resulting savings in mass, volume, and power.
In this paper we describe observed failures of optocouplers on the TOPEX/Poseidon (T/P) ocean measuring satellite. An indirect assessment is made of proton doses by the spacecraft, and these data are compared with laboratory proton irradiations of optocouplers. It is shown that the T/P failures occur at expected doses for proton-induced displacement damage.
A seventh set of heavy ion single event effects (SEE) test data have been collected since the last IEEE publications. SEE trends are indicated for several functional classes of ICs.
The state of understanding of the destructive SEGR event in power MOSFETs is relatively mature with large published efforts, both experimental and theoretical. However, gasps remain in the uderstanding of the phenomenon, including unexplained anomalies, emperical-only dependencies on some important device and incident ion physical parameters, and limited insight into latent effets.
The sixth set of heavy ion single event effects (SEE) test data have been collected since the last IEEE publications in December issues of IEEE - Nuclear Science Transactions for 1985, 1987, 1989, 1991, and the IEEE Workshop Record, 1993. Trends in SEE susceptibility (including soft errors and latchup) for state-of- are evaluated.
The effects of radiation on fused biconical taper wavelength division multiplexers are presented. A theoretical model indicates that index changes in the fiber are primarily responsible for the degradation of these devices.
This paper examines various factors in bipolar device construction and design, and discusses their impact on radiation hardness. The intent of the paper is to improve understanding of the underlying mechanisms for practical devices without special test structures, and to provide (1) guidance in ways to select transistor designs that are more resistant to radiation damage, and (2) methods to estimate the maximum amount of damage that might be expected from a basic transistor design. The latter factor is extremely important in assessing the risk that future lots of devices will be substantially below design limits, which are usually based on test data for older devices.
This paper reports on hard errors induced by single ions in dynamic memories. For ions with atomic number below 80, hard errors in DRAMs appear to be similar to the hard errors reported in previous work on SRAMs. One feature of these hard errors is that they tend to recover gradually with time, because of annealing, and are thus partially recoverable. However, for gold ions, a second type of hard error was discovered which is not recoverable, and appears to be due to catastrophic internal shorting rather than small changes in leakage current. Thus, nonrecoverable errors will likely occur even in devices which eliminate the extreme sensitivity to leakage current that is inherent in 4-T SRAMs and DRAMs. It is important to understand the mechanism that is responsible for nonrecoverable errors, and investigate the effect of device scaling.
This paper presents an evaluation of trends in SEE susceptibility (including soft errors and latchup) for state-of-the-art parts.
JPL's X2000 avionics design pioneers new territory by specifying a non-volatile memory (NVM) board based on flash memories. The Samsung 128Mb device chosen was found to demonstrate bit errors (mostly program disturbs) and block-erase failures that increase with cycling. Low temperature, certain pseudo- random patterns, and, probably, higher bias increase the observable bit errors. An experiment was conducted to determine the wearout dependence of the bit errors to 100k cycles at cold temperature using flight-lot devices (some pre-irradiated). The results show an exponential growth rate, a wide part-to-part variation, and some annealing behavior.