Suchergebnisse

Framing the new START Treaty -- The talks take shape -- Rome - the red ballroom -- The run to Moscow -- October breakthrough on verification -- Senate Observer Group in Geneva -- Losing the race to December -- Copenhagen - the presidents meet -- January regroup in Moscow -- Long winter slog -- April glitter in Prague castle -- Up to the Senate -- The last votes -- The gold standard treaty - lessons learned.

Due to commercial and government interest in devices capable of functioning in high-power, high-frequency space applications, radiation tolerant AlGaN/GaN devices have been under study in recent years. Passivation of the AlGaN surface by (Si3N4) prevents electron trapping and enhances the 2DEG, but it also increases gate leakage currents, which can lead to device failure. This study sought information about current leakage mechanisms by introducing displacement damage close to the Si3N4/AlGaN interface. The effects of irradiation damage around the Si3N4/AlGaN interface on irradiation-induced leakage current were investigated for three thicknesses of a Si3N4 passivation layer in addition to an unpassivated sample. AlGaN/GaN samples were irradiated at room temperature with 15-50keV nitrogen ions. Hall measurements determined mobility and 2DEG carrier density. C-V measurements provided insight into charge location and effects of the band structure. Pre-irradiation measurements were compared to the irradiation results to determine the types and amounts of damage done in the devices. Post-irradiation C-V measurements showed greater than 50% decrease in capacitance and an average -3V shift in Vth which persisted in the passivated samples. Post-irradiation Hall measurements showed decreases in mobility for both passivated and unpassivated samples. Carrier concentration decreased for passivated samples but increased for the unpassivated sample.

The United States has come full circle from its harsh criticism of the 1990s sanctions regime against Iraq, relying on UN Security Council sanctions as the major means of pressuring Tehran over its nuclear programme. Other members of the Security Council, especially Russia, have been less enthusiastic. Experience with North Korea indicates that the major powers might be placing too much emphasis on the Security Council process and not enough on improved instruments of sanctions policy represented by new US financial laws and procedures after rr September, which have done much to improve banking due diligence and other measures in pursuit of the fight against terrorism. The United States and Russia might be more willing to work together in the realm of anti-terrorism financial measures to pressure Iran than they have been at the UN Security Council. (Survival / SWP)