| 摘要 |
PURPOSE:To enable operation at high speed by dividing a base region into a plurality of sections and increasing electron affinity in the sections separate from an emitter. CONSTITUTION:A base region having electron affinity larger than an N-type wide band gap-emitter region formed by an emitter layer 16 consisting of N- Al0.3Ga0.7As (a dopant:Si and concentration: 1X10<19> cm<-3>) in a thickness of 200nm is divided into two sections of a first base layer 17 and a second base layer 18 having the section length of approximately the mean free path of electrons. The title bipolar transistor is composed of a semiconductor material having electron affinity which is kept constant in each section but is reduced in sections nearer to the emitter region. Ballistic electrons 1 injected through deltaEc fly only in a mean free path lambda and lose kinetic energy, diffuse and travel slightly, and start ballistic flight again by the conduction-band bottom discontinuity deltaE'c of the abrupt hetero-junction interface of P<+>-Al15Ga0.85As and P<+>-GaAs, thus flying only in a mean free path lambda' and reaching to a collector region.
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