Heterojunction Bipolar Transistor

Patent metadata

Field	Value
Publication number	US-2024030288-A1
Application number	US-202018255280-A
Country	US
Kind code	A1
Filing date	Dec 17, 2020
Priority date	Dec 17, 2020
Publication date	Jan 25, 2024
Grant date	—

Abstract

A hetero-junction bipolar transistor includes a substrate made of InP, and a sub-collector layer, a collector layer, a base layer, an emitter layer, and an emitter cap layer formed on the substrate. The base layer is made up of a first base layer on the collector layer side and a second base layer on the emitter layer side. The first base layer has a constant Sb molar composition ratio in the thickness direction. In the second base layer, the Sb molar composition ratio increases in the thickness direction toward the emitter layer.

First claim

1 .- 3 . (canceled)

4 . A hetero-junction bipolar transistor comprising:
a substrate comprising InP; a collector layer on the substrate and comprising a first group III-V compound semiconductor; a base layer on the collector layer and comprising a second group III-V compound semiconductor comprising Ga, As, and Sb; and an emitter layer on the base layer and comprising a third group III-V compound semiconductor different from the second group III-V compound semiconductor; wherein an Sb molar composition ratio of the base layer decreases from a side closest to the emitter layer to a middle of the base layer in a thickness direction; and wherein the Sb molar composition ratio of the base layer is constant from the middle of the base layer to a side closest to the collector layer in the thickness direction.

5 . The hetero-junction bipolar transistor according to claim 4 , wherein:
the Sb molar composition ratio of the base layer is in a range from 0.49 to 0.53 in a vicinity of an interface with the emitter layer; the Sb molar composition ratio of the base layer is in a range from 0.3 to 0.4 in a vicinity of an interface with the collector layer; and the base layer has a thickness of 35 nm or less.

6 . The hetero-junction bipolar transistor according to claim 5 , wherein:
the emitter layer comprises an InGaP layer comprising InGaP in a part in the thickness direction; and a Ga molar composition ratio of the InGaP layer increases toward the base layer in a range from greater than 0 to 0.25.

7 . The hetero-junction bipolar transistor according to claim 4 , wherein:
the emitter layer comprises an InGaP layer comprising InGaP in a part in the thickness direction; and a Ga molar composition ratio of the InGaP layer increases toward the base layer in a range from greater than 0 to 0.25.

8 . A method of forming a hetero-junction bipolar transistor, the method comprising:
forming a collector layer on a substrate, wherein the collector layer comprises a first group III-V compound semiconductor and the substrate comprises InP; forming a base layer on the collector layer, wherein the base layer comprises a second group III-V compound semiconductor comprising Ga, As, and Sb; and forming an emitter layer on the base layer, wherein the emitter layer comprises a third group III-V compound semiconductor different from the second group III-V compound semiconductor; wherein an Sb molar composition ratio of the base layer decreases from a side closest to the emitter layer to a middle of the base layer in a thickness direction; and wherein the Sb molar composition ratio of the base layer is constant from the middle of the base layer to a side closest to the collector layer in the thickness direction.

9 . The method according to claim 8 , wherein:
the Sb molar composition ratio of the base layer is in a range from 0.49 to 0.53 in a vicinity of an interface with the emitter layer; the Sb molar composition ratio of the base layer is in a range from 0.3 to 0.4 in a vicinity of an interface with the collector layer; and the base layer has a thickness of 35 nm or less.

10 . The method according to claim 9 , wherein:
the emitter layer comprises an InGaP layer comprising InGaP in a part in the thickness direction; and a Ga molar composition ratio of the InGaP layer increases toward the base layer in a range from greater than 0 to 0.25.

11 . The method according to claim 8 , wherein:
the emitter layer comprises an InGaP layer comprising InGaP in a part in the thickness direction; and a Ga molar composition ratio of the InGaP layer increases toward the base layer in a range from greater than 0 to 0.25.

Assignees

• Nippon Telegraph & Telephone

Inventors

• Mitsuhara Manabu
• Shiratori Yuta

Classifications

• H10D62/137

  Collector regions of BJTs · CPC title

• H10D62/136

  of heterojunction BJTs  (vertical heterojunction BJTs having one or more non-monocrystalline Group IV elements H10D10/861) · CPC title

• H10D10/021

  of heterojunction BJTs [HBT] · CPC title

• H10D62/824

  comprising only Group III-V materials heterojunctions, e.g. GaN/AlGaN heterojunctions · CPC title

• H10D62/177 Primary

  Base regions of bipolar transistors, e.g. BJTs or IGBTs · CPC title