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The total ionizing dose (TID) effect of gamma-ray (γ-ray) irradiation on HfOx based resistive random access memory was investigated by electrical and material characterizations. The memory states can sustain TID level ~5.2 Mrad (HfO2) without significant change in the functionality or the switching characteristics under pulse cycling. However, the stability of the filament is weakened after irradiation as memory states are more vulnerable to flipping under the electrical stress. X-ray photoelectron spectroscopy was performed to ascertain the physical mechanism of the stability degradation, which is attributed to the Hf-O bond breaking by the high-energy γ-ray exposure. [ABSTRACT FROM AUTHOR]

With an increasingly complex worldwide nuclear environment, nuclear forensics provides a deterrent through proper attribution. Identifying the type of event is important in the attribution process, and the lithium battery has the potential to provide significant information for this purpose. The incident neutron spectral fluence is related to the type of nuclear event. The lithium battery is built using materials that can be used to assess the number of incident neutrons, as well as provide threshold detection dependant on the neutron energy. This study looks at correlating the production of various long-lived radioactive isotopes to the incident neutron spectrum. The analysis uses known nuclear cross sections and battery properties to calculate the number of long-lived radioactive elements that can be produced in the solid winding of the active battery elements, which include the cathode, separator, and anode. Some isotopes are only produced above a threshold energy, such as ^58Co, which requires 10.6 MeV neutrons. Other isotopes such as ^3H are produced through various reaction channels, mostly ^6Li(n,\alpha)^3H, which is an exothermic reaction, and is not associated with a threshold energy. [ABSTRACT FROM PUBLISHER]

A RHBD high performance cache fabricated on 90 nm bulk CMOS is presented. Test silicon cache data arrays can read and write at 1.02 GHz. Irradiation to 2 Mrad(Si) negligibly impacts standby current. The cache is write-through, and relies on error checking to allow cache invalidation when single event upsets or potential single event transients are detected. The write-through cache architectural state will then naturally be reloaded by the ensuing microprocessor operations. Single cycle invalidation is supported. Single event error ion beam test results are presented, as is a description of measured single event effects in array and peripheral circuits and their mitigation by the design. [ABSTRACT FROM PUBLISHER]

The design and electrical characterization of a total ionizing dose hardened by a design static random access memory (SRAM) cell using annular layout and guard rings are presented. Since foundry SRAM cells can be validated during process development and manufacturing ramp but radiation hardening by design cells cannot, we use a specialized test structure to validate the cell design here. Stability, manufacturability, and hardness are experimentally investigated using a 4 kbit SRAM structure, fabricated on one version of the foundry 90 nm process. The structure, combined with a novel test and simulation based extraction procedure, allows direct measurement of the as-fabricated cell electrical characteristics. Variation of the SRAM switching points due to irradiation as well as the individual transistor threshold voltage variability is measured in the SRAM array test structure. Irradiation tests show negligible impact on switching voltage and increase in the standby current less than 1.5% after 2 Mrad(Si). The effects on the cell margins are also analyzed. The specific SRAM cell layout, which uses a very low aspect ratio, is intended to minimize multibit upset of horizontally adjacent cells. This impact is also discussed with measured heavy ion results. [ABSTRACT FROM AUTHOR]

Complex interplay between hydrogen-related defect formation and passivation is observed in irradiated bipolar transistors. Hydrogen soaking experiments are performed to evaluate the dependence of defect buildup and annealing in gated lateral bipolar transistors on hydrogen exposure. Comparisons of the radiation responses of transistors tested in 2009 to identical devices from the same wafer tested in 2003 show that aging has reduced the amount of radiation-induced interface trap and oxide trapped charge formation in most cases. These results demonstrate that the way in which the radiation response of a hydrogen-sensitive device evolves with age depends on whether hydrogen is diffusing into or out of the device, and whether the initial defect concentration favors passivation or depassivation reactions. These results strongly suggest that hydrogen exposure cannot replace low-dose-rate irradiation in ELDRS tests for bipolar devices and ICs without extensive characterization testing. [ABSTRACT FROM AUTHOR]

The introduction of computer-equipped classrooms into engineering education has brought with it a host of opportunities and issues. Herein, some of the challenges and successes for creating an environment for active learning within computer-based classrooms are described. The particular teaching approach developed for undergraduate electrical engineering courses is presented. Longitudinal assessment data regarding in-class utilization of computers in the context of achieving program and course learning outcomes are shared. [ABSTRACT FROM AUTHOR]