Reduction of turn-off time in silicon pn diodes by low energy (270 keV) electron irradiation

Abstract

We developed a new method for lifetime control in silicon power devices, which employs low energy (270 keV) electron irradiation and hydrogen annealing. This method can reduce irradiation cost significantly compared to a conventional method using high energy (2 MeV) protons or electrons. In our measurements, electron-irradiated silicon pn diodes show different turn-off characteristics, after they are annealed in nitrogen or hydrogen atmosphere. Hydrogen-annealed diodes show higher forward voltages and smaller turn-off charges. These results suggest that the defects introduced by low energy electron irradiation are converted to different defects by hydrogen annealing, and that the minority carrier lifetime is reduced due to the new defects.