High-voltage thyristors and diodes made of neutron-irradiated silicon

Neutron irradiation is a way to produce homogeneous and well-defined phosphorus doping in large diameter silicon crystals. One major application of such silicon is in the field of high-voltage power devices. The relation between resistivity and breakdown voltage determined for neutron-irradiated silicon is in good agreement with the theory of Sze and Gibbons. It is shown that by changing from conventionally doped silicon to neutron-irradiated silicon noticeable increases in the blocking capability of thyristors can be achieved without an increase of the n-base width. Production of power thyristors with blocking voltages of 3 to 5 kV has been successful, indicating that applications of neutron-irradiated silicon have already left the laboratory stage.