Heterojunction bipolar transistor with base electrode having Schottky barrier contact to the emitter

A semiconductor device comprising:

• a collector layer made of a first conductive type semiconductor;
• a base layer made of a second conductive type semiconductor;
• an emitter layer made of the first conductive type semiconductor, said collector layer, base layer and emitter layer being laminated successively on a substrate;
• a base electrode constituted of a metal layer or an intermetallic compound layer, said base electrode extending through said emitter layer and said base layer from a part of a surface of said emitter layer to said collector layer;
• and
• an emitter electrode disposed at another part of the surface of said emitter layer,
• wherein said emitter layer having a first forbidden band gap energy Eg1, said base layer having a second forbidden band gap energy Eg2, and a junction formed between said base electrode and said emitter layer having a Schottky barrier height .phi.MS;
• Eg1, Eg2 and .phi.MS satisfying the following equation:
• Eg1>.phi.MS>Eg2.

A semiconductor device comprising:

• a collector layer made of a first conductive type semiconductor;
• a base layer made of a second conductive type semiconductor;
• and
• an emitter layer made of the first conductive type semiconductor, said collector layer, base layer and emitter layer being laminated successively on a substrate,
• a base electrode being in contact with the base layer and the emitter layer,
• wherein said emitter layer having a first forbidden band gap energy Eg1, said base layer having a second forbidden band gap energy Eg2, and a junction formed between said base electrode and said emitter layer having a Schottky barrier height .phi.MS;
• Eg1, Eg2 and .phi.MS satisfying the following equation:
• Eg1>.phi.MS>Eg2.