# US 7,612,390 B2 · Heterojunction transistors including energy barriers

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 7,612,390 B2
- Document ID: US7612390B2
- Status: Granted
- Kind: B2
- Application number: 11/357,752
- Filed: 2006-02-17
- Published: 2006-11-16
- Granted: 2009-11-03
- Earliest claimed: 2004-02-05
- Assignees: Cree, Inc.
- Inventors: Adam William Saxler; Yifeng Wu; Primit Parikh
- Web page: https://patentgrep.com/patent/US7612390B2

## CPC

- H10D 30/4738: {having multiple donor layers}
- H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT}
- H10D 30/4732: {using Group III-V semiconductor material}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 30/4735: {having delta-doped or planar-doped donor layers}
- H10D 30/801: {FETs having heterojunction gate electrodes}
- H10D 62/854: further characterised by the dopants
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A heterojunction transistor may include a channel layer comprising a Group III nitride, a barrier layer comprising a Group III nitride on the channel layer, and an energy barrier comprising a layer of a Group III nitride including indium on the channel layer such that the channel layer is between the barrier layer and the energy barrier. The barrier layer may have a bandgap greater than a bandgap of the channel layer, and a concentration of indium (In) in the energy barrier may be greater than a concentration of indium (In) in the channel layer. Related methods are also discussed.

## Claims

### Claim 1

A heterojunction transistor comprising:
a channel layer comprising a Group III nitride;
a barrier layer comprising a Group III nitride adjacent the channel layer wherein the barrier layer has a bandgap greater than a bandgap of the channel layer;
an energy barrier comprising a layer of a Group III nitride including indium adjacent the channel layer such that the channel layer is between the barrier layer and the energy barrier wherein the energy barrier has a narrower bandgap than the channel layer; and
a hole source layer comprising a Group III nitride adjacent the energy barrier such that the energy barrier is between the channel layer and the hole source layer and a hole source region is induced at an interface between the hole source layer and the energy barrier.

### Claim 2 (depends on 1)

A heterojunction transistor according to claim 1 wherein the channel layer and the barrier layer cooperatively induce a two-dimensional electron gas at an interface between the channel layer and the barrier layer.

### Claim 3 (depends on 1)

A heterojunction transistor according to claim 1 wherein the energy barrier comprises a layer of InxGa1-xN (0<x≦1).

### Claim 4 (depends on 3)

A heterojunction transistor according to claim 3 wherein the energy barrier comprises a layer of InN.

### Claim 5 (depends on 3)

A heterojunction transistor according to claim 3 wherein the energy barrier comprises a layer of InxGa1-xN (0<x<1).

### Claim 6 (depends on 5)

A heterojunction transistor according to claim 5 wherein a mole fraction of InN (indium nitride) in an InN/GaN alloy of the energy barrier is at least about 1%.

### Claim 7 (depends on 6)

A heterojunction transistor according to claim 6 wherein a mole fraction of InN (indium nitride) in an InN/GaN alloy of the energy barrier is in the range of about 1% to about 50%.

### Claim 8 (depends on 7)

A heterojunction transistor according to claim 7 wherein a mole fraction of InN (indium nitride) in an InN/GaN alloy of the energy barrier is in the range of about 4% to about 16%.

### Claim 9 (depends on 1)

A heterojunction transistor according to claim 1 wherein the energy barrier opposes movement of carriers away from the channel layer.

### Claim 10 (depends on 1)

A heterojunction transistor according to claim 1 wherein the energy barrier comprises a quantum well.

### Claim 11 (depends on 1)

A heterojunction transistor according to claim 1 further comprising:
source, drain, and gate contacts adjacent the barrier layer such that the barrier layer is between the channel layer and the source, drain, and gate contacts; and
a substrate adjacent the energy barrier such that the energy barrier is between the substrate and the channel layer.

### Claim 12 (depends on 1)

A heterojunction transistor according to claim 1 wherein the barrier layer has a thickness in the range of about 0.1 nm to about 10 nm.

### Claim 13 (depends on 1)

A heterojunction transistor according to claim 1 wherein the barrier layer and the energy barrier are separated by a distance in the range of about 5 nm to about 30 nm.

### Claim 14 (depends on 1)

A heterojunction transistor according to claim 1 wherein the channel layer comprises a layer of AlyGa1-yN (0≦y<1), the barrier layer comprises a layer of AlzGa1-zN (0<z≦1), and y and z are different.

### Claim 15 (depends on 1)

A heterojunction transistor according to claim 1 wherein a concentration of Al in the barrier layer is greater than a concentration of Al in the channel layer.

### Claim 16

A heterojunction transistor comprising:
a channel layer;
a barrier layer adjacent the channel layer wherein the barrier layer and the channel layer cooperatively induce a two-dimensional electron gas at an interface between the channel layer and the barrier layer;
an energy barrier adjacent the channel layer such that the channel layer is between the barrier layer and the energy barrier wherein the energy barrier opposes movement of carriers away from the channel layer wherein the energy barrier has a narrower bandgap than the channel layer; and
a hole source layer adjacent the enemy barrier such that the energy barrier is between the channel layer and the hole source layer wherein a hole source region is induced at an interface between the hole source layer and the energy barrier.

### Claim 17 (depends on 16)

A heterojunction transistor according to claim 16 wherein the channel layer comprises a first layer of a Group III nitride, wherein the barrier layer comprises a second layer of a Group III nitride, and wherein the energy barrier comprises a third layer of a Group III nitride.

### Claim 18 (depends on 16)

A heterojunction transistor according to claim 16 wherein the energy barrier comprises a quantum well.

### Claim 19 (depends on 16)

A heterojunction transistor according to claim 16 wherein the energy barrier comprises a layer of InxGa1-xN (0<x≦1).

### Claim 20 (depends on 19)

A heterojunction transistor according to claim 19 wherein the energy barrier comprises a layer of InN.

### Claim 21 (depends on 19)

A heterojunction transistor according to claim 19 wherein the energy barrier comprises a layer of InxGa1-xN (0<x<1).

### Claim 22 (depends on 21)

A heterojunction transistor according to claim 21 wherein a mole fraction of InN (indium nitride) in an InN/GaN alloy of the energy barrier is at least about 1%.

### Claim 23 (depends on 22)

A heterojunction transistor according to claim 22 wherein a mole fraction of InN (indium nitride) in an InN/GaN alloy of the energy barrier is in the range of about 1% to about 50%.

### Claim 24 (depends on 23)

A heterojunction transistor according to claim 23 wherein a mole fraction of InN (indium nitride) in an InN/GaN alloy of the energy barrier is in the range of about 4% to about 16%.

### Claim 25 (depends on 16)

A heterojunction transistor according to claim 16 wherein the energy barrier has a thickness in the range of no more than about 50 Angstroms.

### Claim 26 (depends on 16)

A heterojunction transistor according to claim 16 further comprising:
source, drain, and gate contacts adjacent the barrier layer such that the barrier layer is between the channel layer and the source, drain, and gate contacts; and
a substrate adjacent the energy barrier such that the energy barrier is between the substrate and the channel layer.

### Claim 27 (depends on 16)

A heterojunction transistor according to claim 16 wherein the channel layer comprises a Group III nitride, wherein the barrier comprises a Group III nitride, and wherein the barrier layer has a bandgap greater than a bandgap of the channel layer.

### Claim 28 (depends on 16)

A heterojunction transistor according to claim 16 wherein the channel layer comprises a layer of AlyGa1-yN (0≦y<1), the barrier layer comprises a layer of AlzGa1-zN (0<z≦1), and y and z are different.

### Claim 29 (depends on 16)

A heterojunction transistor according to claim 16 further comprising:
a cap layer comprising a Group III nitride adjacent the barrier layer such that the barrier layer is between the cap layer and the channel layer, wherein a concentration of Ga in the cap layer is greater than a concentration of Ga in the barrier layer.

### Claim 30 (depends on 16)

A heterojunction transistor according to claim 16 wherein the barrier layer comprises a Group III nitride and the channel layer comprises a Group III nitride, and wherein a concentration of Al in the barrier layer is greater than a concentration of Al in the channel layer.

### Claim 31 (depends on 1)

A heterojunction transistor according to claim 1 wherein the energy barrier has a thickness of no more than about 50 Angstroms.

### Claim 32 (depends on 1)

A heterojunction transistor according to claim 1 further comprising:
a cap layer comprising a Group III nitride adjacent the barrier layer such that the barrier layer is between the cap layer and the channel layer, wherein a concentration of Ga in the cap layer is greater than a concentration of Ga in the barrier layer.

### Claim 33 (depends on 1)

A heterojunction transistor according to claim 1 wherein the hole source layer has a higher bandgap than the energy barrier.

### Claim 34 (depends on 1)

A heterojunction transistor according to claim 1 wherein the hole source layer is undoped.

### Claim 35 (depends on 1)

A heterojunction transistor according to claim 1 wherein the hole source layer is doped with p-type dopants.

### Claim 36 (depends on 1)

A heterojunction transistor according to claim 1 wherein the energy barrier has a first conductivity type and the hole source layer has a second conductivity type opposite the first conductivity type.

### Claim 37 (depends on 16)

A heterojunction transistor according to claim 16 wherein the hole source layer has a higher bandgap than the energy barrier.

### Claim 38 (depends on 16)

A heterojunction transistor according to claim 16 wherein the hole source layer is undoped.

### Claim 39 (depends on 16)

A heterojunction transistor according to claim 16 wherein the hole source layer is doped with p-type dopants.

### Claim 40 (depends on 16)

A heterojunction transistor according to claim 16 wherein the energy barrier has a first conductivity type and the hole source layer has a second conductivity type opposite the first conductivity type.

### Claim 41 (depends on 1)

A heterojunction transistor according to claim 1 wherein a concentration of indium (In) in the energy barrier is greater than a concentration of indium (In) in the channel layer.

### Claim 42 (depends on 41)

A heterojunction transistor according to claim 41 wherein the channel layer comprises a layer of AlyGa1-yN (0≦y<1).

### Claim 43 (depends on 1)

A heterojunction transistor according to claim 1 wherein the energy barrier has a larger lattice constant than the channel layer.

### Claim 44 (depends on 16)

A heterojunction transistor according to claim 16 wherein the energy barrier has a larger lattice constant than the channel layer.