Reverse current instability of power silicon diodes (thyristors) at high temperature and the junction surface leakage current

Examples of reverse (blocking) I-V characteristics for PN junctions from available commercial power diodes and thyristors are shown. The surface leakage component of the junction reverse current is the primary component for standard recovery junctions. For fast recovery junctions, a secondary surface leakage current at lower applied voltage, may dominate the bulk component towards the maximum working reverse voltage. At high operation temperature, the dissipated power corresponding to the surface current component induces uncontrolled junction temperature peaks. Reverse current instability due to these temperature peaks, leads to device catastrophic failure if operation beyond the temperature and voltage ratings specified in the data sheets is permitted. Further reduction of the level of reverse current on behalf of the surface component, enables reliable operation at junction temperature higher than the maximum specified value in the data sheets. Higher working reverse voltage reaching the breakdown voltage is also possible.