A highly interdigitated GTO power switch with recessed gate structure

A highly interdigitated power GTO has been realized with a new technology based on reactive ion etching. The characteristic feature of the device are 50 µm wide vertically walled cathode fingers 30 µm apart from each other. The gate level is recessed 20 µm. The gate metalization is contacted directly on the recessed p-base having a doping concentration ≤2 ċ 10¹⁶cm^-3. With an ohmic load the turn off dI/dt is about 250 A/µsec cm²(related to the shorted anode area). Storage and fall time are well below 1 µsec at turn off gains close to one. The critical current crowding effect observed in conventional GTOs does not occur in the presented highly interdigitated structure.