Abstract: A bipolar transistor is provided with both high voltage and high frequency capabilities. A semiconductor body of a resistivity between 10 and 100 ohm-cm forms the collector region of the transistor and has an epitaxial semiconductor layer grown on a major surface thereof of a resistivity between about 0.5 and 10 ohm-cm and of a thickness between about 20 and 100 microns and of a conductivity type opposite from the body. At least one emitter region and integral emitter electrode are alloyed into the epitaxial layer preferably in annular rings. A base region is formed in the epitaxial layer between the emitter and semiconductor body and around the emitter region, said base region having a minimum thickness between the emitter region and the semiconductor body in the interior of the body of less than 20 and preferably between 5 and 10 microns.