Reverse recovery time measurements of epitaxial silicon p- n junctions at low temperatures

Abstract

Reverse recovery times of epitaxial Si p- n junctions with approximately linear impurity gradient were measured as a function of current and breakdown voltage between room temperature and 2°K. Diodes with a breakdown voltage, V B , of larger than about 11 V (at 300°K) have a constant current period of time interval t 1 which decreases approximately linearly with temperature until all the mobile charges are frozen out. For V B between about 6·2 V and 11 V the time interval t 1 decreases linearly with temperature when cooled from room temperature, but below a certain temperature, t 1 varies only slightly. For V B smaller than about 6·2 V the time interval t 1 increases linearly for decreasing temperatures, but below a certain temperature, t 1 varies only slightly. The diodes with V B < 11 V have a finite storage time when extrapolated to absolute zero which is believed to be related to impurity band and metallic conduction of doped silicon.