535 research outputs found
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Total ionizing dose effects on MOS and bipolar devices in the natural space radiation environment
Mechanisms that control the response of MOS and bipolar devices to ionizing radiation in the natural space environment are briefly reviewed. Standard tests based on room-temperature irradiation and elevated temperature annealing are described for MOS devices to bound the effects of oxide and interface-trap charge in space. For bipolar devices that exhibit enhanced low-dose-rate sensitivity, a standard test equivalent to that developed for MOS devices is not available. However, screening techniques based on room temperature and/or elevated temperature irradiations are described which can minimize the risk to spacecraft and satellite electronics from this phenomenon
Optical Technologies for UV Remote Sensing Instruments
Over the last decade significant advances in technology have made possible development of instruments with substantially improved efficiency in the UV spectral region. In the area of optical coatings and materials, the importance of recent developments in chemical vapor deposited (CVD) silicon carbide (SiC) mirrors, SiC films, and multilayer coatings in the context of ultraviolet instrumentation design are discussed. For example, the development of chemically vapor deposited (CVD) silicon carbide (SiC) mirrors, with high ultraviolet (UV) reflectance and low scatter surfaces, provides the opportunity to extend higher spectral/spatial resolution capability into the 50-nm region. Optical coatings for normal incidence diffraction gratings are particularly important for the evolution of efficient extreme ultraviolet (EUV) spectrographs. SiC films are important for optimizing the spectrograph performance in the 90 nm spectral region. The performance evaluation of the flight optical components for the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument, a spectroscopic instrument to fly aboard the Solar and Heliospheric Observatory (SOHO) mission, designed to study dynamic processes, temperatures, and densities in the plasma of the upper atmosphere of the Sun in the wavelength range from 50 nm to 160 nm, is discussed. The optical components were evaluated for imaging and scatter in the UV. The performance evaluation of SOHO/CDS (Coronal Diagnostic Spectrometer) flight gratings tested for spectral resolution and scatter in the DGEF is reviewed and preliminary results on resolution and scatter testing of Space Telescope Imaging Spectrograph (STIS) technology development diffraction gratings are presented
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Radiation-induced charge trapping in bipolar base oxides
Capacitance-voltage and thermally stimulated current methods are used to investigate radiation induced charge trapping in bipolar base oxides. Results are compared with models of oxide and interface trap charge buildup at low electric fields
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Where constructionism and critical realism converge: interrogating the domain of epistemological relativism
The paper interrogates the status, nature and significance of epistemological relativism as a key element of constructionism and critical realism. It finds that epistemological relativism is espoused by authorities in critical realism and marginalized or displaced in the field of management and organization studies, resulting in forms of analysis that are empirically, but not fully critically, realist. This evaluation prompts reflection on the question of whether, how and with what implications epistemological relativism might be recast at the heart of critical realist studies of management and organization
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Mechanisms of heavy-ion induced gate rupture in thin oxides
Single event gate rupture (SEGR) is a catastrophic failure mode that occurs in dielectric materials that are struck by energetic heavy ions while biased under a high electric field condition. SEGR can reduce the critical electric field to breakdown to less than half the value observed in normal voltage ramp reliability tests. As electric fields in gate oxides increase to greater than 5 MV/cm in advanced MOS technologies, the impact of SEGR on the reliability of space based electronics must be assessed. In this summary, the authors explore the nature of SEGR in oxides with thickness from 7 nm to less than 5 nm, where soft breakdown is often observed during traditional reliability tests. They discuss the possible connection between the present understanding of SEGR and voltage stress breakdown models
Characterizing SRAM Single Event Upset in Terms of Single and Double Node Charge Collection
A well-collapse source-injection mode for SRAM SEU is demonstrated through TCAD modeling. The recovery of the SRAM s state is shown to be based upon the resistive path from the p+-sources in the SRAM to the well. Multiple cell upset patterns for direct charge collection and the well-collapse source-injection mechanisms are then predicted and compared to recent SRAM test data
A first-principles approach to closing the "10-100 eV gap" for charge-carrier thermalization in semiconductors
The present work is concerned with studying accurately the energy-loss
processes that control the thermalization of hot electrons and holes that are
generated by high-energy radiation in wurtzite GaN, using an ab initio
approach. Current physical models of the nuclear/particle physics community
cover thermalization in the high-energy range (kinetic energies exceeding ~100
eV), and the electronic-device community has studied extensively carrier
transport in the low-energy range (below ~10 eV). However, the processes that
control the energy losses and thermalization of electrons and holes in the
intermediate energy range of about 10-100 eV (the "10-100 eV gap") are poorly
known. The aim of this research is to close this gap, by utilizing density
functional theory (DFT) to obtain the band structure and dielectric function of
GaN for energies up to about 100 eV. We also calculate charge-carrier
scattering rates for the major charge-carrier interactions (phonon scattering,
impact ionization, and plasmon emission), using the DFT results and first-order
perturbation theory. With this information, we study the thermalization of
electrons starting at 100 eV using the Monte Carlo method to solve the
semiclassical Boltzmann transport equation. Full thermalization of electrons
and holes is complete within ~1 and 0.5 ps, respectively. Hot electrons
dissipate about 90% of their initial kinetic energy to the electron-hole gas
(90 eV) during the first ~0.1 fs, due to rapid plasmon emission and impact
ionization at high energies. The remaining energy is lost more slowly as phonon
emission dominates at lower energies (below ~10 eV). During the thermalization,
hot electrons generate pairs with an average energy of ~8.9 eV/pair (11-12
pairs per hot electron). Additionally, during the thermalization, the maximum
electron displacement from its original position is found to be on the order of
100 nm.Comment: 23 pages, 20 figures. This LaTex file uses RevTex4.2 from AP
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Effects on focused ion beam irradiation on MOS transistors
The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 {mu}m minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga{sup +} focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated
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Radiation-induced gain degradation in lateral PNP BJTs with lightly and heavily doped emitters
Ionizing radiation may cause failures in ICs due to gain degradation of individual devices. The base current of irradiated bipolar devices increases with total dose, while the collector current remains relatively constant. This results in a decrease in the current gain. Lateral PNP (LPNP) transistors typically exhibit more degradation than vertical PNP devices at the same total dose, and have been blamed as the cause of early IC failures at low dose rates. It is important to understand the differences in total-dose response between devices with heavily- and lightly-doped emitters in order to compare different technologies and evaluate the applicability of proposed low-dose-rate hardness-assurance methods. This paper addresses these differences by comparing two different LPNP devices from the same process: one with a heavily-doped emitter and one with a lightly-doped emitter. Experimental results demonstrate that the lightly-doped devices are more sensitive to ionizing radiation and simulations illustrate that increased recombination on the emitter side of the junction is responsible for the higher sensitivity
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