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Understanding the Implications of a LINAC's Microstructure on Devices and Photocurrent Models

IEEE Transactions on Nuclear Science

McLain, Michael L.; McDonald, Joseph K.; Hembree, Charles E.; Sheridan, Timothy J.; Weingartner, Thomas A.; Dodd, Paul E.; Shaneyfelt, Marty R.; Hartman, Elmer F.; Black, Dolores A.

The effect of a linear accelerator's (LINAC's) microstructure (i.e., train of narrow pulses) on devices and the associated transient photocurrent models are investigated. The data indicate that the photocurrent response of Si-based RF bipolar junction transistors and RF p-i-n diodes is considerably higher when taking into account the microstructure effects. Similarly, the response of diamond, SiO2, and GaAs photoconductive detectors (standard radiation diagnostics) is higher when taking into account the microstructure. This has obvious hardness assurance implications when assessing the transient response of devices because the measured photocurrent and dose rate levels could be underestimated if microstructure effects are not captured. Indeed, the rate the energy is deposited in a material during the microstructure peaks is much higher than the filtered rate which is traditionally measured. In addition, photocurrent models developed with filtered LINAC data may be inherently inaccurate if a device is able to respond to the microstructure.

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Temperature Effects on the Total Ionizing Dose Response of TaOx-based Memristive Bit Cells

2017 17th European Conference on Radiation and Its Effects on Components and Systems, RADECS 2017

McLain, Michael L.; McDonald, Joseph K.; Hjalmarson, Harold P.; Serrano, Jason D.; Cuoco, Roy P.; Hanson, Donald J.; Hughart, David R.; Marinella, Matthew J.; Hartman, E.F.

The effects of temperature on the total ionizing dose (TID) response of tantalum oxide (TaOx) memristive bit cells are investigated. The TaOx devices were manufactured by Sandia National Laboratories (SNL). In-situ data were obtained as a function of temperature, accumulated dose, and bias at the Gamma Irradiation Facility (GIF). The data indicate that devices reset into the high resistance off-state exhibit decreases in resistance when the temperature is increased. However, an increased susceptibility to TID at elevated temperatures was not observed.

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The susceptibility of TaOx-based memristors to high dose rate ionizing radiation and total ionizing dose

IEEE Transactions on Nuclear Science

McLain, Michael L.; Hjalmarson, Harold P.; Sheridan, Timothy J.; Mickel, Patrick R.; Hanson, Donald J.; McDonald, Joseph K.; Hughart, David R.; Marinella, Matthew J.

This paper investigates the effects of high dose rate ionizing radiation and total ionizing dose (TID) on tantalum oxide (TaOx) memristors. Transient data were obtained during the pulsed exposures for dose rates ranging from approximately 5.0 × 107rad(Si)/s to 4.7 × 108rad(Si)/s and for pulse widths ranging from 50 ns to 50 μs. The cumulative dose in these tests did not appear to impact the observed dose rate response. Static dose rate upset tests were also performed at a dose rate of ∼3.0 × 108rad(Si)/s. This is the first dose rate study on any type of memristive memory technology. In addition to assessing the tolerance of TaOx memristors to high dose rate ionizing radiation, we also evaluated their susceptibility to TID. The data indicate that it is possible for the devices to switch from a high resistance off-state to a low resistance on-state in both dose rate and TID environments. The observed radiation-induced switching is dependent on the irradiation conditions and bias configuration. Furthermore, the dose rate or ionizing dose level at which a device switches resistance states varies from device to device; the enhanced susceptibility observed in some devices is still under investigation. Numerical simulations are used to qualitatively capture the observed transient radiation response and provide insight into the physics of the induced current/voltages.

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21 Results
21 Results