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US 7,067,858 B2Granted
Heterojunction bipolar transistor with a base layer that contains bismuth
AssigneeSony Corporation
InventorIchiro Hase
Life of this patent
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Abstract
A heterojunction bipolar transistor (HBT) with improved characteristics is provided. A III–V compound semiconductor having Bi added thereto is used for a base layer of a GaAs-based or InP-based HBT. For example, a GaAs-based HBT is formed by successively stacking a subcollector layer made of n+-GaAs, a collector layer made of n−-GaAs, a base layer made of p+-GaAsBi, an emitter layer made of n-InGaP, a first cap layer made of n-GaAs, and a second cap layer made of n+-InGaAs on a substrate 1 made of single crystal GaAs.
Claims1
A semiconductor device comprising:
- an emitter layer;
- a base layer;
- and
- a collector layer, the sum of a band gap and electron affinity of said emitter layer being larger than the sum of a band gap and electron affinity of said base layer, wherein said base layer contains Bi in an amount which provides a potential gradient that increases movement speed of the electrons from the base layer to the collector layer.
1 more element
Dependencies are inferred from the claim text.