Application of radiation enhanced diffusion to microwave transistor fabrication

The use of preferential Radiation Enhanced Diffusion (RED) of impurities from an n
⁺
silicon substrate doped with antimony to an n
^-
silicon epitaxial layer by proton irradiation followed by the phosphorus atom implantation into an n
^-
epitaxial layer, again followed by the proton irradiation, has been successfully applied to microwave transistor fabrication. This increases the power gain by reducing collector capacitance, C
c
, while maintaining high f
T
, which is difficult to realize by conventional means.