On the Electron Extraction Mechanism in Punch-through NPN Fast Recovery Diodes

Electron extraction mechanism of the Punch-through (PT) NPN diode is fully investigated and experimentally demonstrated. Similar to the N-type Schottky barrier, the PT -NPN region in the PT -NPN diode features a unipolar structure for electron unidirectional conduction. The hole injection of the PT -NPN diode can be tuned to a level close to that of the N-Schottky implemented PT -NPN (N-Schottky PT - NPN) diode due to the electron extraction. Experimental results show that softness factor of the PT - NPN diode is increased by 20% compared with that of the N -Schottky PT-NPN diode. In addition, the PT -NPN diode attains a stable breakdown voltage of 1268 V with a low leakage current. However, the leakage current of the N -Schottky PT - NPN diode is increased by 10 times when the barrier height is changed by 0.3 eV.