Publications

IEEE Transactions on Nuclear Science

Hjalmarson, Harold P.; Witczak, Steven C.; Schultz, Peter A.; Bowman, Duane J.

Abstract not provided.

IEEE Transactions on Nuclear Science

Witczak, Steven C.; Shaneyfelt, Marty R.; Schwank, James R.; Winokur, Peter S.

Metal-oxide-silicon capacitors fabricated in a bi-polar process were examined for densities of oxide trapped charge, interface traps and deactivated substrate acceptors following high-dose-rate irradiation at 100 C. Acceptor neutralization near the Si surface occurs most efficiently for small irradiation biases in depletion. The bias dependence is consistent with compensation and passivation mechanisms involving the drift of H{sup +} ions in the oxide and Si layers and the availability of holes in the Si depletion region. Capacitor data from unbiased irradiations were used to simulate the impact of acceptor neutralization on the current gain of an npn bipolar transistor. Neutralized acceptors near the base surface enhance current gain degradation associated with radiation-induced oxide trapped charge and interface traps by increasing base recombination. The additional recombination results from the convergence of carrier concentrations in the base and increased sensitivity of the base to oxide trapped charge. The enhanced gain degradation is moderated by increased electron injection from the emitter. These results suggest that acceptor neutralization may enhance radiation-induced degradation of linear circuits at elevated temperatures.

IEEE Transactions on Nuclear Science

Schwank, James R.; Witczak, Steven C.; Riewe, Leonard C.; Shaneyfelt, Marty R.; Shaneyfelt, Marty R.; Dodd, Paul E.; Jones, Rhonda L.; Draper, Bruce L.

Abstract not provided.

IEEE Transactions on Nuclear Science

Shaneyfelt, Marty R.; Schwank, James R.; Witczak, Steven C.; Winokur, Peter S.; Riewe, Leonard C.; Hash, Gerald L.

Abstract not provided.

Journal of Applied Physics

Witczak, Steven C.; Winokur, Peter S.; Lacoe, Ronald C.; Mayer, Donald C.

An improved charge separation technique for metal-oxide-silicon (MOS) capacitors is presented which accounts for the deactivation of substrate dopants by hydrogen at elevated irradiation temperatures or small irradiation biases. Using high-frequency capacitance-voltage measurements, radiation-induced inversion voltage shifts are separated into components due to oxide trapped charge, interface traps, and deactivated dopants, where the latter is computed from a reduction in Si capacitance. In the limit of no radiation-induced dopant deactivation, this approach reduces to the standard midgap charge separation technique used widely for the analysis of room-temperature irradiations. The technique is demonstrated on a p-type MOS capacitor irradiated with 60Co γ rays at 100°C and zero bias, where the dopant deactivation is significant. © 2000 American Institute of Physics.

Witczak, Steven C.; Schwank, James R.; Shaneyfelt, Marty R.; Winokur, Peter S.

Dopant deactivation at 100 C is measured in bipolar Si-SiO{sub 2} structures as a function of irradiation bias. The deactivation occurs most efficiently at small biases in depletion and is consistent with passivation and compensation mechanisms involving hydrogen.

Schwank, James R.; Shaneyfelt, Marty R.; Jones, Rhonda L.; Draper, Bruce L.; Dodd, Paul E.; Witczak, Steven C.; Riewe, Leonard C.

Large differences in charge buildup in SOI buried oxides can result between x-ray and Co-60 irradiations. The effects of bias configuration and substrate type on charge buildup and hardness assurance issues are explored.

Shaneyfelt, Marty R.; Schwank, James R.; Witczak, Steven C.; Riewe, Leonard C.; Winokur, Peter S.; Hash, Gerald L.

Thermal-stress effects are shown to have a significant impact on the enhanced low-dose-rate sensitivity of linear bipolar circuits. Implications of these results on hardness assurance testing and mechanisms are discussed.