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 for 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. Since this is a design theory, rigor is sacrificed in some cases for simplicity. Despite this, comparison of the theoretical predictions with experimental results usually shows good agreement. The possibility of applying the results to other hemispherical geometries, such as point contact diodes, is considered briefly.