M.H. Mendenhall

Vanderbilt University, Нашвилл, Michigan, United States

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Publications (112)139.9 Total impact

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    ABSTRACT: Single-event upsets in HfO2/Hf 1T1R Resistive Random Access Memory (RRAM) structures are experimentally demonstrated by generating current transients in the access transistors of the memory cells. The relationship between the single-event upset threshold of the RRAM and the applied voltage is exponential, which is verified using TPA laser analysis and heavy-ion irradiation. Multiple-Event Upsets (MEUs) also occur, where individual ions incrementally change the RRAM’s resistance until their cumulative effect causes an upset. Single-event models are presented that allow direct correlation of the voltage across the RRAM, caused by the ion-generated current transient, and the change in RRAM resistance. The RRAM is vulnerable only in the high resistance state, when a voltage capable of writing to the cell is applied to the bit line. This is approximately 0.5% of the memory element’s operation time, leading to relatively low projected upset rates.
    IEEE Transactions on Nuclear Science 08/2014; 61(4):1717-1725. DOI:10.1109/TNS.2014.2321833 · 1.46 Impact Factor
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    ABSTRACT: We present experimental evidence of single-event upsets in 28 and 45 nm CMOS SRAMs produced by single energetic electrons. Upsets are observed within 10% of nominal supply voltage for devices built in the 28 nm technology node. Simulation results provide supporting evidence that upsets are produced by energetic electrons generated by incident X-rays. The observed errors are shown not to be the result of “weak bits” or photocurrents resulting from the collective energy deposition from X-rays. Experimental results are consistent with the bias sensitivity of critical charge for direct ionization effects caused by low-energy protons and muons in these technologies. Monte Carlo simulations show that the contributions of electron-induced SEU to error rates in the GEO environment depend exponentially on critical charge.
    IEEE Transactions on Nuclear Science 12/2013; 60(6):4122-4129. DOI:10.1109/TNS.2013.2286523 · 1.46 Impact Factor
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    ABSTRACT: Charge collection by multiple junctions is investigated using broadbeam heavy-ion and backside laser current transient measurements. The probability that significant charge is collected by more than one junction is greater for laser-generated events compared to heavy-ion measurements, which is attributed to the larger carrier generation track radius for the laser. With both sources, the probability of collecting charge on multiple junctions saturates at high charge generation levels. Effects caused by the interaction between junctions on the transient current waveforms is determined using position-correlated two-photon absorption laser analysis. The total charge collected for ion strikes between four adjacent junctions is shown to be approximately the same as for a direct strikes on a single junction, even though the incident ion does not pass through the depletion region of a biased junction.
    IEEE Transactions on Nuclear Science 12/2013; 60(6):4159-4165. DOI:10.1109/TNS.2013.2286701 · 1.46 Impact Factor
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    ABSTRACT: Measurements of single particle displacement damage are presented as discrete increases in reverse-biased diode leakage current, or current steps, caused by individual heavy ions in $^{252}{rm Cf}$-irradiated JFET diodes. The maximum size of measured current steps agrees with calculations obtained from the expression for Shockley-Read-Hall generation when the radiation-induced defect density is derived from Monte Carlo simulations of atomic displacements and the electric field enhancement of defect emission is taken into account. The distribution of the current steps shows good agreement with experimental data.
    IEEE Transactions on Nuclear Science 12/2013; 60(6):4094-4102. DOI:10.1109/TNS.2013.2289737 · 1.46 Impact Factor
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    ABSTRACT: This anthology contains contributions from eleven different groups, each developing and/or applying Monte Carlo-based radiation transport tools to simulate a variety of effects that result from energy transferred to a semiconductor material by a single particle event. The topics span from basic mechanisms for single-particle induced failures to applied tasks like developing websites to predict on-orbit single event failure rates using Monte Carlo radiation transport tools.
    IEEE Transactions on Nuclear Science 06/2013; 60(3):1876-1911. DOI:10.1109/TNS.2013.2262101 · 1.46 Impact Factor
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    ABSTRACT: Single particle displacement damage events are reported in silicon diodes irradiated with 252Cf and 241Am. In situ measurements of reverse current show the result of displacement damage incurred from individual fission fragments in 252Cf irradiated diodes. Discrete increases in reverse current exceeding 20 fA are measured. The increases are temporally correlated with fission fragment-induced ionization events. The ratio of the damage factor associated with fission fragments to the damage factor associated with alpha particles is in good agreement with the ratio of non-ionizing energy loss calculated for fission fragments to NIEL calculated for alpha particles.
    IEEE Transactions on Nuclear Science 12/2012; 59(6):3054-3061. DOI:10.1109/TNS.2012.2224131 · 1.46 Impact Factor
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    ABSTRACT: We describe a tool suite, CRÈME, which combines existing capabilities of CREME96 and CREME86 with new radiation environment models and new Monte Carlo computational capabilities for single event effects and total ionizing dose.
    IEEE Transactions on Nuclear Science 12/2012; 59(6):3141. DOI:10.1109/TNS.2012.2218831 · 1.46 Impact Factor
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    ABSTRACT: An efficient method for estimating the characteristics of ion-induced current pulse transients is presented and related to the corresponding mechanisms of single-event charge collection. The method is focused on characterizing the prompt response of a reverse biased p-n junction under relatively low level conditions (LET <; 10 MeV-cm2/mg). This method is shown to be accurate when compared to 3D finite element simulations, while reducing solution time such that current pulse calculations can be run in series with both energy deposition and circuit simulations.
    IEEE Transactions on Nuclear Science 12/2012; 59(6):2704-2709. DOI:10.1109/TNS.2012.2218830 · 1.46 Impact Factor
  • IEEE Transactions on Nuclear Science 12/2012; 59(6):3054-3061. · 1.46 Impact Factor
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    ABSTRACT: Spin-transfer torque film stacks and devices having in-plane magnetization were irradiated using a cobalt-60 gamma source. Samples were also exposed to 2 MeV and 220 MeV protons. Measurements of magnetization vs. field, ferromagnetic resonance, and tunnel magnetoresistance were performed on the film stacks before and after exposure to these sources and no changes were observed in the associated material properties. Spin-transfer torque devices were exposed to the same sources and show no changes in bit-state or write performance.
    IEEE Transactions on Nuclear Science 12/2012; 59(6):3027-3033. DOI:10.1109/TNS.2012.2223487 · 1.46 Impact Factor
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    ABSTRACT: Monte-Carlo radiation transport simulations are used to evaluate the implications of track structure on the response of microelectronics to energy deposition from ionizing radiation events. Results show that average track structure models cannot fully account for effects on microelectronics devices from energy deposition by δ-rays. Additionally, results indicate that δ-ray energy deposition events are capable of depositing up to 10 keV of energy within a 50 nm cube at radial distances greater than 10 μm from an ionizing particle event.
    Applied Physics Letters 08/2012; 101(5). DOI:10.1063/1.4742163 · 3.52 Impact Factor
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    ABSTRACT: The effects of 10-keV and 400-keV endpoint-energy bremsstrahlung x-rays have been studied using the Monte Carlo simulator, MRED, for MOS capacitors with HfO2 gate dielectrics and TiN and TaN metal gates. We compute the reduction in dose that occurs for 10-keV x-ray irradiation of thin HfO2 gate dielectrics sandwiched between the metal gate and the Si substrate. We quantify the effects of back-end-of-line metallization layers, including copper interconnects, W vias, and borophosphosilicate glass (BPSG) and SiO2 passivation layers for low and medium energy x-rays. For thick metallization stacks irradiated by 10-keV x-rays, dose enhancement or attenuation can occur, depending on material type and overlayer thicknesses. For similar stacks irradiated with 400-keV endpoint-energy bremsstrahlung x-rays, significant dose enhancement is observed.
    IEEE Transactions on Nuclear Science 12/2011; 58(6):3139-3144. DOI:10.1109/TNS.2011.2169279 · 1.46 Impact Factor
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    ABSTRACT: Experimental cross-section data for the interaction of protons with Al, Co, and Au at intermediate energies are compared with the predictions of the nuclear reaction models CEM03, BIC, Bertini INC, and INCL-ABLA. Fission cross-section data for the interaction of protons with W and Au in the energy range 50 MeV-3 GeV are also compared with the considered models. The study reveals that all of the models are satisfactory in limited ranges. However, of these, the CEM03 code from Los Alamos exhibits the broadest applicability for radiation effects computations.
    IEEE Transactions on Nuclear Science 12/2011; 58(6):3134-3138. DOI:10.1109/TNS.2011.2169989 · 1.46 Impact Factor
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    ABSTRACT: Neutron-induced charge collection data and computer simulations presented here show that the presence of high-Z materials, like tungsten, can increase the single event upset (SEU) and multiple cell upset (MCU)cross sections of high critical charge $({\rm Q}_{\rm crit})$ devices exposed to the terrestrial neutron environment because of interactions with high energy $(> {100}~{\hbox {MeV}})$ neutrons. Time-of-flight data and computer simulations presented here demonstrate that 14 MeV neutrons do not produce highly ionizing secondary particles. Thus, 14 MeV neutrons can only simulate the SEU response of 65 nm SRAM devices in the terrestrial neutron environment for devices with a ${\rm Q}_{\rm crit} < 27~{\rm fC}$, and can simulate the 2-bit MCU response to within a factor of two only for very low ${\rm Q}_{\rm crit}$ devices, $< 1.2~{\rm fC}$.Additionally, it is shown that 14 MeV neutrons cannot adequately simulate the 3 or more bit MCU response for typical 65 nm SRAM devices.
    IEEE Transactions on Nuclear Science 12/2011; 58(6):2591-2598. DOI:10.1109/TNS.2011.2171716 · 1.46 Impact Factor
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    ABSTRACT: Kinetic energy, angular distribution, and isobaric cross section data for A = 7–25 fragments formed in p + 27Al reaction at bombarding energy of 180 MeV are compared with the calculations of the Binary Cascade Model (BIC), the Cascade Exciton Model (CEM), JQMD/PHITS, as well as the Statistical Model with Final State Interaction (SMFSI). For completeness, the kinetic energy spectra of light particles (n, p, α) formed in p + 27Al reaction at bombarding energy of 156 MeV are also presented. A general agreement between the data and predictions of these models is found. However, disagreement with the data for the yields of light-mass fragments as well as near-target fragments is also found and discussed. The importance of this comparative study to simulation and analysis of radiation effects on microscopic electrical components operating in space is also discussed.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 11/2011; 269(21):2463-2468. DOI:10.1016/j.nimb.2011.07.098 · 1.19 Impact Factor
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    ABSTRACT: Silicon-On-lnsulator (SOI) has long been recognized to provide inherent resistance to transient ionizing radiation effects due to the isolation from the substrate. The buried insulating layer (buried oxide BOX) is also known to introduce problematic considerations for total ionizing dose (TID) radiation effects, particularly for fully-depleted (FD) SOI. Recent work in characterization of TID effects in partially depleted (PD) SOI indicates that the inherently high doping levels of the body region result in insensitivity to TID. The pros and cons generally apply to all SOI-based technologies, including thin-film CMOS as well as thick film bipolar, LDMOS, and power MOSFETs. Space and military devices continue to be an opportunity for thin and thick SOI devices where the BOX limits global photocurrents in high dose-rate environments, and local photocurrents in heavy-ion space environments. At the same time, single-event effects (SEE) have become an increasing reliability concern in terrestrial electronics, particularly in sub-65 nm CMOS circuits. Small amounts of charge representing each bit of information, high clock speeds, low operating voltages, and high packing densities all exacerbate the sensitivity to ionizing particles. Terrestrial neutron effects, and more recently direct ionization by protons and muons, are significant considerations in present and emerging electronic devices, motivating a closer look at SEE in ultra-thin (UT) FDSOI.
    2011 IEEE International SOI Conference; 10/2011
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    ABSTRACT: Gold nanoparticles (GNPs) are of considerable interest for use as a radiosensitizer, because of their biocompatibility and their ability to increase dose deposited because of their high mass energy absorption coefficient. Their sensitizing properties have been verified experimentally, but a discrepancy between the experimental results and theoretical predictions suggests that the sensitizing effect does not depend solely on gold’s superior absorption of energetic photons. This work presents the results of three sets of experiments that independently mapped out the energy dependence of the radiosensitizing effects of GNPs on plasmid DNA suspended in water. Incident photon energy was varied from 11.8 to 80 keV through the use of monochromatic synchrotron and broadband X-rays. These results depart significantly from the theoretical predictions in two ways: First, the sensitization is significantly larger than would be predicted; second, it does not vary with energy as would be predicted from energy absorption coefficients. These results clearly demonstrate that the effects of GNP-enhanced therapies cannot be predicted by considering additional dose alone and that a greater understanding of the processes involved is necessary for the development of future therapeutics.
    The Journal of Physical Chemistry C 09/2011; DOI:10.1021/jp206854s · 4.84 Impact Factor
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    Marcus H. Mendenhall, Robert A. Weller
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    ABSTRACT: In Monte Carlo particle transport codes, it is often important to adjust reaction cross sections to reduce the variance of calculations of relatively rare events, in a technique known as non-analogous Monte Carlo. We present the theory and sample code for a Geant4 process which allows the cross section of a G4VDiscreteProcess to be scaled, while adjusting track weights so as to mitigate the effects of altered primary beam depletion induced by the cross section change. This makes it possible to increase the cross section of nuclear reactions by factors exceeding 10^4 (in appropriate cases), without distorting the results of energy deposition calculations or coincidence rates. The procedure is also valid for bias factors less than unity, which is useful, for example, in problems that involve computation of particle penetration deep into a target, such as occurs in atmospheric showers or in shielding.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 09/2011; 667. DOI:10.1016/j.nima.2011.11.084 · 1.32 Impact Factor
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    ABSTRACT: Monte Carlo simulations demonstrate that electrons in a Europa-like radiation environment produce single events capable of depositing more than 100 keV in a shielded focal plane array (FPA). Aluminum shielding slows down high energy free space electrons through collisions. Incident electrons can also generate secondary particles within shielding through electromagnetic cascades, nuclear interactions, and other mechanisms. When incident electrons and secondary particles deposit energy in FPA pixels, the result is transient increases in background noise. We compare the energy deposition integral cross sections and estimate the single event effect rate for a range of electron energies incident upon an FPA shielded with 1, 5, and 10 cm of aluminum.
    IEEE Transactions on Nuclear Science 07/2011; DOI:10.1109/TNS.2011.2129531 · 1.46 Impact Factor
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    ABSTRACT: SEU enhancements were introduced into a radiation hardened 90 nm CMOS technology to achieve upset immunity. An incremental enhancement approach that enables various SEU/performance trade-off was demonstrated on the same basic SRAM cell to achieve various degrees of hardness, by the selective utilization of enhancement features. Single event upset testing, as well as MRED simulation, have demonstrated a significant enhancements achieved with a minimal performance penalty.
    IEEE Transactions on Nuclear Science 06/2011; 58(3):975-980. DOI:10.1109/TNS.2011.2128882 · 1.46 Impact Factor