Patent ID: 7323725
Filing Date: 2008-01-29
Classification: B82Y,H01L

Abstract:
1. A semiconductor device comprising: a substrate; a semiconductor multi-layered structure formed on the substrate, the multi-layered structure comprising an emitter layer, a base layer and a collector layer composed of a group III-V n-type compound semiconductor, the base layer lying between the emitter layer and the collector layer; a quantum dot barrier layer lying between the emitter layer and the base layer; a collector electrode, a base electrode and an emitter electrode respectively connected to the collector layer, base layer and emitter layer; wherein the quantum dot barrier layer comprising a plurality of quantum dots and first and second barrier layers sandwiching the quantum dots from the emitter layer side and the base layer side, respectively, and the first and second barrier layers being composed of a semiconductor having a band gap greater than that of the semiconductor composing the quantum dots; each of the quantum dots having a convex portion that is convex to the base layer; a spacer layer being sandwiched between the quantum dot barrier layer and the base layer; a collector barrier layer being sandwiched between the base layer and the collector layer; the interface between the emitter layer and the quantum dot barrier layer being parallel to the surface of the substrate; the interface between the second barrier layer and the spacer layer having a curved portion convex to the collector layer; the base layer having a curved portion convex to the collector layer; the interface between the spacer layer and the base layer having a curved portion convex to the collector layer; and the interface between the base layer and the collector barrier layer having a curved portion convex to the collector layer.