HF switching transistor with low collector resistance - has high cut=off current with doping concentration in substrate zone between prescribed limits

摘要

The transistor for high-frequency switching in an aerial system which has a low collector resistance and maximum cut-off frequency when the current is at a high level. It consists of a silicon substrate of one type of conductivity and high impurity doping. There is an epitaxial layer on the substrate with a lower degree of doping (2 x 1012) and of the same type of conductivity. The epitaxial layer forms a collector-base junction with the base region in the surface of the substrate. The emitter zone is in the same surface and is surrounded by the base zone. The doping concentration of the substrate lies between an upper and a lower limit of atoms per cubic centimetre, viz 8 x 1017 and 8 x 1016. The distance between the collector-base junction and the junction between substrate and epitaxial layer is a maximum of 5 microns. The substrate is of n-type conductivity.