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Impact of Surface Recombination on Single-Event Charge Collection in an SOI Technology

IEEE Transactions on Nuclear Science

Tonigan, Andrew M.; Ball, Dennis; Vizkelethy, Gyorgy V.; Black, Jeffrey B.; Black, Dolores A.; Trippe, James M.; Bielejec, Edward S.; Alles, Michael L.; Reed, Robert S.; Schrimpf, Ronald D.

Semiconductor-insulator interfaces play an important role in the reliability of integrated devices; however, the impact of these interfaces on the physical mechanisms related to single-event effects has not been previously reported. We present experimental data that demonstrate that single-event charge collection can be impacted by changes in interface quality. The experimental data, combined with simulations, show that single-event response may depend on surface recombination at interface defects. The effect depends on strike location and increases with increasing linear energy transfer (LET). Surface recombination can affect single-event charge collection for interfaces with a surface recombination velocity (SRV) of 1000 cm/s and is a dominant charge collection mechanism with SRV > 10^{5} cm/s.

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TYPE Journal Article YEAR 2021
DOIOSTIScopus

Optimization of target lifetime for production of 14 MeV neutrons

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Wampler, William R.; Doyle, B.L.; Cooper-Snow, Wendy S.; Vizkelethy, Gyorgy V.; Jasica, Matthew J.

Two methods are examined for extending the life of tritium targets for production of 14 MeV neutrons by the 3H(2H,n)4He nuclear reaction. With thick film targets the neutron production rate decreases with time due to isotope exchange of tritium in the film with implanted deuterium. In this case, the target life is maximized by operating the target at elevated temperature where the implanted deuterium mixes by thermal diffusion throughout the entire thickness of the film. The number of neutrons obtained from a target is then proportional to the initial tritium content of the film. A novel thin-film target design was also developed and tested. With these thin-film targets, the incident deuterium is implanted through the tritide into the underlying substrate material. A thin permeation barrier layer between the tritide film and substrate, reduces the rate of tritium loss from the tritide film. Good thin-film target performance was achieved using W and Fe for the barrier and substrate materials respectively. Thin-film targets were fabricated and tested and shown to produce similar number of neutrons as thick-film targets while using only a small fraction of the amount of tritium.

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TYPE Journal Article YEAR 2020
DOIOSTIScopus

Response of GaN-Based Semiconductor Devices to Ion and Gamma Irradiation

Aguirre, Brandon A.; King, Joseph K.; Manuel, Jack E.; Vizkelethy, Gyorgy V.; Bielejec, Edward S.; Griffin, Patrick J.

GaN has electronic properties that make it an excellent material for the next generation of power electronics; however, its radiation hardening still needs further understanding before it is used in radiation environments. In this work we explored the response of commercial InGaN LEDs to two different radiation environments: ion and gamma irradiations. For ion irradiations we performed two types of irradiations at the Ion Beam Lab (IBL) at Sandia National Laboratories (SNL): high energy and end of range (EOR) irradiations. For gamma irradiations we fielded devices at the gamma irradiation facility (GIF) at SNL. The response of the LEDs to radiation was investigated by IV, light output and light output vs frequency measurements. We found that dose levels up to 500 krads do not degrade the electrical properties of the devices and that devices exposed to ion irradiations exhibit a linear and non- linear dependence with fluence for two different ranges of fluence levels. We also performed current injection annealing studies to explore the annealing properties of InGaN LEDs.

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TYPE SAND Report YEAR 2020
DOIOSTI

Photocurrent from single collision 14-MeV neutrons in GaN and GaAs

IEEE Transactions on Nuclear Science

Jasica, Matthew J.; Wampler, William R.; Vizkelethy, Gyorgy V.; Hehr, Brian D.; Bielejec, Edward S.

Accurate predictions of device performance in 14-MeV neutron environments rely upon understanding the recoil cascades that may be produced. Recoils from 14-MeV neutrons impinging on both gallium nitride (GaN) and gallium arsenide (GaAs) devices were modeled and compared to the recoil spectra of devices exposed to 14-MeV neutrons. Recoil spectra were generated using nuclear reaction modeling programs and converted into an ionizing energy loss (IEL) spectrum. We measured the recoil IEL spectra by capturing the photocurrent pulses produced by single neutron interactions with the device. Good agreement, with a factor of two, was found between the model and the experiment under strongly depleted conditions. However, this range of agreement between the model and the experiment decreased significantly when the bias was removed, indicating partial energy deposition due to cascades that escape the active volume of the device not captured by the model. Consistent event rates across multiple detectors confirm the reliability of our neutron recoil detection method.

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TYPE Journal Article YEAR 2020
DOIOSTIScopus

14 MeV DT Neutron Test Facility at the Sandia Ion Beam Laboratory

Wampler, William R.; Doyle, Barney L.; Vizkelethy, Gyorgy V.; Bielejec, Edward S.; Snow, Clark S.; Styron, Jedediah D.; Jasica, Matthew J.

This report documents work done at the Sandia Ion Beam Laboratory to develop a capability to produce 14 Me neutrons at levels sufficient for testing radiation effects on electronic materials and components. The work was primarily enabled by a laboratory directed research and development (LDRD) project. The main elements of the work were to optimize target lifetime, test a new thin- film target design concept to reduce tritium usage, design and construct a new target chamber and beamline optimized for high-flux tests, and conduct tests of effects on electronic devices and components. These tasks were all successfully completed. The improvements in target performance and target chamber design have increased the flux and fluence of 14 MV neutrons available at the test location by several orders of magnitude. The outcome of the project is that a new capability for testing radiation-effects on electronic components from 14 MeV neutrons is now available at Sandia National Laboratories. This capability has already been extensively used for many qualification and component evaluation and development tests.

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TYPE SAND Report YEAR 2019
DOIOSTI
Results 26–50 of 175
Results 26–50 of 175