Influence of Electric Field in Diffusion Region upon Breakdown in Germanium n-p Junctions

Abstract

The high current density existing at near‐breakdown reverse bias of an n‐p junction produces, by Ohm's law, an electric field. If the effect of this field is included in the solution for diode current, it is found that it can significantly affect the breakdown characteristic. It can, for example, produce an increase in injected photocurrent resembling multiplication, even though multiplication is not occurring in the junction itself. Alternatively, if multiplication is present, it can produce instability and breakdown before the avalanche in the space‐charge region itself becomes unstable (i.e., before the multiplication factor becomes infinite). These predicted phenomena have been observed in a series of germanium n‐p junctions. Closely allied with these phenomena is the observation of a region of ``soft breakdown'' in many germanium junctions, which appears to be a bulk effect.