Dynamic avalanche in diodes with local lifetime control by means of palladium

The increase of the static breakdown voltage and the reduction of dynamic avalanche in a fast recovery 2.5 kV/150 A P-i-N diode subjected to the radiation enhanced diffusion of a palladium are discussed. The in-diffusing palladium compensates the doping profile in a lightly doped N-base close to the anode junction. Using a device simulation, the increase of the breakdown voltage and the reduction of the dynamic avalanche are explained by the reduction of peak electric field in the additional low-doped P-type layer created by the compensation effect. This is presented for both a dc and transient device operation and confirmed experimentally as well. An improved technology curve for the static versus recovery losses at a high line voltage has been obtained. A high thermal budget of deep levels and a low leakage current are additional benefits of the method.