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Final report on LDRD project 105967 : exploring the increase in GaAs photodiode responsivity with increased neutron fluence

Blansett, Ethan B.; Serkland, Darwin K.; Geib, K.M.; Peake, Gregory M.; Fleming, Robert M.; Wrobel, Diana L.

A previous LDRD studying radiation hardened optoelectronic components for space-based applications led to the result that increased neutron irradiation from a fast-burst reactor caused increased responsivity in GaAs photodiodes up to a total fluence of 4.4 x 10{sup 13} neutrons/cm{sup 2} (1 MeV Eq., Si). The silicon photodiodes experienced significant degradation. Scientific literature shows that neutrons can both cause defects as well as potentially remove defects in an annealing-like process in GaAs. Though there has been some modeling that suggests how fabrication and radiation-induced defects can migrate to surfaces and interfaces in GaAs and lead to an ordering effect, it is important to consider how these processes affect the performance of devices, such as the basic GaAs p-i-n photodiode. In this LDRD, we manufactured GaAs photodiodes at the MESA facility, irradiated them with electrons and neutrons at the White Sands Missile Range Linac and Fast Burst Reactor, and performed measurements to show the effect of irradiation on dark current, responsivity and high-speed bandwidth.

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TYPE SAND Report YEAR 2008
DOIOSTI

Simulation of neutron displacement damage in bipolar junction transistors using high-energy heavy ion beams

Vizkelethy, Gyorgy V.; Bielejec, Edward S.; Doyle, Barney L.; Buller, Daniel L.; Fleming, Robert M.; Hjalmarson, Harold P.

Electronic components such as bipolar junction transistors (BJTs) are damaged when they are exposed to radiation and, as a result, their performance can significantly degrade. In certain environments the radiation consists of short, high flux pulses of neutrons. Electronics components have traditionally been tested against short neutron pulses in pulsed nuclear reactors. These reactors are becoming less and less available; many of them were shut down permanently in the past few years. Therefore, new methods using radiation sources other than pulsed nuclear reactors needed to be developed. Neutrons affect semiconductors such as Si by causing atomic displacements of Si atoms. The recoiled Si atom creates a collision cascade which leads to displacements in Si. Since heavy ions create similar cascades in Si we can use them to create similar damage to what neutrons create. This LDRD successfully developed a new technique using easily available particle accelerators to provide an alternative to pulsed nuclear reactors to study the displacement damage and subsequent transient annealing that occurs in various transistor devices and potentially qualify them against radiation effects caused by pulsed neutrons.

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TYPE SAND Report YEAR 2006
DOIOSTI

Measurement of temperature-dependent defect diffusion in proton-irradiated GaN(Mg, H)

Journal of Applied Physics

Fleming, Robert M.; Myers, S.M.

Deuterated p-type GaN(Mg, 2H) films were irradiated at room temperature with 1 MeV protons to create native point defects with a concentration approximately equal to the Mg doping (5 × 10 19 cm -3). The samples were then annealed isothermally at a succession of temperatures while monitoring the infrared absorption due to the H local mode of the MgH defect. As the samples were annealed, the MgH absorption signal decreased and a new mode at slightly higher frequency appeared, which has been associated with the approach of a mobile nitrogen interstitial. We used the time dependence of the MgH absorption to obtain a diffusion barrier of the nitrogen interstitial in p-type GaN of 1.99 eV. This is in good agreement with theoretical calculations of nitrogen interstitial motion in GaN. © 2000 American Institute of Physics.

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TYPE Journal Article YEAR 2006
ScopusOSTIDOI
Results 26–42 of 42
Results 26–42 of 42