Patent ID: 9397204
Filing Date: 2016-07-19
CPC Classification: H01L

Claim Text:
1. A heterojunction bipolar transistor comprising: a collector layer composed of a semiconductor containing GaAs as a main component; a first base layer that forms a heterojunction with the collector layer, the first base layer being composed of a semiconductor containing a material as a main component, the material being lattice-mismatched to the main component of the collector layer, and the first base layer having a film thickness less than a critical thickness at which a misfit dislocation is introduced; a second base layer joined to the first base layer, the second base layer being composed of a semiconductor containing a material as a main component, the material being lattice-matched to the main component of the collector layer; an emitter layer that forms a heterojunction with the second base layer, and in a state before the first base layer and the second base layer are joined together, the energy of the bottom of the conduction band of the second base layer is equal to or higher than a value obtained by subtracting the thermal energy of a free electron at room temperature from the energy of the bottom of the conduction band of the first base layer.