MULTIPLE PROTON ENERGY IRRADIATION FOR IMPROVED GTO THYRISTORS

Proton irradiation using three proton energies and a variety of fluence combinations has been used to improve the trade-off between steady-state and turn-off losses for Gate Turn-Off (GTO) thyristors. Using a fluence of 9 . 10(10) cm-2 near the anode, 4 . 10(10) cm-2 in the middle of the device and 1 . 10(10) cm-2 close to the blocking junction, the tum-off energy is reduced by 50% relative to electron-irradiated standard components. The electrical results are consistent with the results of infrared free carrier absorption measurements performed on single GTO thyristor cells during both steady state and turn-off. The charge dynamics in selected regions of the thyristor is discussed and charge carrier lifetime is deduced by analytical methods for various proton fluence and energy combinations.