Fast soft recovery thyristors with axial lifetime profile fabricated using iridium diffusion

The paper presents experimental results on samples of fast soft reverse recovery thyristors with axial carrier lifetime gradient in the wide base, realised using combination of iridium diffusion with low dose of electron irradiation. Using this technique, fast thyristors of ITAV=960 A, VDRM=3 kV, turn-off time tq≈110 μs and reverse recovery charge Qrr≈700 μC, were fabricated. The softness factor tf/ts≈1 at −dIT/dt=50 A/μs. Devices can be used in e.g. frequency converters based on the current source inverter.