Symmetrical silicon epitaxial transistors

A symmetrical silicon mesa transistor, which has high symmetry of current gains and low saturation resistance and is very useful in certain switching circuits, is fabricated by utilizing the latest techniques. A p-type wafer with very low resistivity is used as the collector of the transistor, an n-type epitaxial layer grown on the wafer as the base and a p-type region diffused into the layer as the emitter.