Abstract: An exemplary embodiment of the invention is a semiconductor device comprising a substrate of a first conductivity type and a subcollector of a second conductivity type provided on the substrate. An intrinsic epitaxial layer is formed on the substrate. A collector region of the second conductivity type is adjacent the subcollector and a base region of the first conductivity type is adjacent the collector region. An emitter region of the second conductivity type is adjacent the base region and the emitter region has an emitter size. The subcollector and collector region both have a size not substantially greater than the emitter size. An alternate embodiment includes a spacer layer formed between the emitter region and the base region.

Abstract: An exemplary embodiment of the invention is a semiconductor device comprising a substrate of a first conductivity type and a subcollector of a second conductivity type provided on the substrate. An intrinsic epitaxial layer is formed on the substrate. A collector region of the second conductivity type is adjacent the subcollector and a base region of the first conductivity type is adjacent the collector region. An emitter region of the second conductivity type is adjacent the base region and the emitter region has an emitter size. The subcollector and collector region both have a size not substantially greater than the emitter size. An alternate embodiment includes a spacer layer formed between the emitter region and the base region.

Abstract: A kinetic energy modulated hot electron transistor (KEMHET) wherein the input voltage does not change the amplitude of the input current, but modulates the kinetic energy of the input electron beam and the probability of electron transition beyond the output collector barrier, thus controlling the current transit coefficient .alpha. and the output current. The transistor comprises two heterojunctions, each consisting of a thin barrier layer and a thick electron drift region. The thick drift regions essentially eliminate variation in barrier shape with bias voltage and reduce junction capacitance. Such a structure can overcome the main problems of a conventional hot electron transistor, such as low current gain and large input capacitance. It has the advantages of high input impedance, high current gain, short transit time, high current density and transconductance, and no feed back capacitance between output and input. In other words, it has the advantages of both FET and bipolar transistor.