Design theory and experiments for abrupt hemispherical P-N junction diodes

The gold bonded germanium diode offers a practical example of a hemispherical p-n junction. In this discussion, a theory is given for the parameters of interest in design of such a junction, i.e., the breakdown voltage, forward current, and transient effects. It is shown that voltage breakdown differs from that for a planar junction due to the concentration of the field by the geometry, this effect leading to lower breakdown voltages. The forward current and reverse transient dependence on the radius of the junction bulk properties, and the thickness of the semiconductor are shown. The nature of the back contact to the semiconductor is also discussed. The theoretical predictions are compared with experimental results for germanium gold bonded diodes, with good agreement. The theories presented also have some application to point contact welded diodes, especially those with heavily doped whiskers, but the scatter in results with these makes it much more difficult to verify the theory.