Calculations of Second Breakdown

A computer program based on an electrothermal model has been used to study the initiation of second breakdown in silicon diodes. Extensive calculations of temperature-dependent static characteristics have been made for a 12-¿m N-type diode doped to 3 × 1015 cm-3. These characteristics, together with the variation of the temporal rate of temperature increase with current, have been used to calculate both current and voltage versus time curves out to 100 ¿s. The resulting calculated power versus time-to-breakdown curve agrees well with published experimental data for 1N4148 diodes (similar doping and geometry) up to 1 ¿s, but the calculated power is lower at longer times for an infinite thermal time constant. Agreement is extended to 100 ¿s with a thermal time constant of 2 ¿s. Calculations have also been made of the temperature variation of current-voltage static characteristics for thin film silicon-on-sapphire diodes. Reasonable agreement is obtained with published measured curves.