Heterojunction bipolar transistor capable of restraining the conductivity modulation of the ballast layer

US6611008B2 · kind B2 · utility

Assignee

• SHARP KABUSHIKI KAISHA · JP

Inventors

• John Twynam · Regensburg, DE
• Yoshiteru Ishimaru · Tenri, JP

Key dates

• Filing date: Mar 10, 2000
• Grant date: Aug 26, 2003
• Expiry date: Mar 10, 2020

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D84/125

Abstract

A heterojunction bipolar transistor has a stack comprised of a base layer, an emitter layer and a ballast layer made of AlGaAs. The emitter layer is comprised of a single layer or a multiplicity of layers, and at least one of which is comprised of a material that prevents hole injection from the base layer into the ballast layer. Thus, the hole injection from the base layer into the emitter layer is prevented. Accordingly, it is able to prevent the conductivity modulation of the ballast layer that is the cause of a deterioration in temperature characteristics.