# US 2018/0026097 A1 · N-channel gallium nitride transistors

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- Number: US 2018/0026097 A1
- Document ID: US20180026097A1
- Status: Published application
- Kind: A1
- Application number: 15/526,735
- Filed: 2014-12-18
- Published: 2018-01-25
- Earliest claimed: 2014-12-18
- Assignees: Intel Corporation
- Applicants: Intel Corporation
- Inventors: Han Wui Then; Sansaptak Dasgupta; Marko Radosavljevic; Seung Hoon Sung; Sanaz K. Gardner; Robert S. Chau
- Web page: https://patentgrep.com/patent/US20180026097A1

## CPC

- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT}
- H10D 30/475: {having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 64/513: {within recesses in the substrate, e.g. trench gates, groove gates or buried gates}
- H10D 64/518: {characterised by their lengths or sectional shapes}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

The present description relates to n-channel gallium nitride transistors which include a recessed gate electrode, wherein the polarization layer between the gate electrode and the gallium nitride layer is less than about 1 nm. In additional embodiments, the n-channel gallium nitride transistors may have an asymmetric configuration, wherein a gate-to drain length is greater than a gate-to-source length. In further embodiment, the n-channel gallium nitride transistors may be utilized in wireless power/charging devices for improved efficiencies, longer transmission distances, and smaller form factors, when compared with wireless power/charging devices using silicon-based transistors.

## Claims

### Claim 1

An n-channel gallium nitride transistor, comprising:
a gallium nitride layer;
a source structure and a drain structure formed in the gallium nitride layer;
a charge inducing layer comprising a polarization layer extending between the source structure and the drain structure;
a 2D electron gas within the gallium nitride layer; and
a gate electrode extending at least partially into the polarization layer, wherein a thickness of a portion of the polarization layer which is between the gate electrode and the gallium nitride layer is less than about 1 nm.

### Claim 2 (depends on 1)

The n-channel gallium nitride transistor of claim 1, further comprising a gate dielectric disposed between the gate electrode and the polarization layer.

### Claim 3 (depends on 1)

The n-channel gallium nitride transistor of claim 1, further comprising a portion of the polarization layer which is not between the gate electrode and the gallium nitride layer is between about 5 nm and 10 nm.

### Claim 4 (depends on 1)

The n-channel gallium nitride transistor of claim 1, wherein the polarization layer is selected from the group consisting of aluminum gallium nitride, aluminum indium nitride, and indium gallium nitride.

### Claim 5 (depends on 1)

The n-channel gallium nitride transistor of claim 1, further including a crystal transition layer disposed between the gallium nitride layer and the polarization layer.

### Claim 6 (depends on 5)

The n-channel gallium nitride transistor of claim 5, wherein the crystal transition layer is selected from the group consisting of indium nitride and aluminum nitride.

### Claim 7 (depends on 1)

The n-channel gallium nitride transistor of claim 1, further including a gate-to-drain length between about 120 nm to about 400 nm and a gate-to-source length between about 5 nm to about 400 nm.

### Claim 8 (depends on 7)

The n-channel gallium nitride transistor of claim 7, wherein the gate-to drain length is greater than the gate-to-source length.

### Claim 9

A method of forming an n-channel gallium nitride transistor, comprising:
forming a gallium nitride layer;
forming a charge inducing layer comprising a polarization layer on the gallium nitride layer to form a 2D electron gas within the gallium nitride layer;
forming a source structure and a drain structure formed in the gallium nitride layer;
forming a recess within the polarization layer between the source structure and the drain structure, wherein a thickness of a portion of the polarization layer which is between the recess and the gallium nitride layer is less than about 1 nm;
forming asymmetrical dielectric spacers of different widths;
forming a gate dielectric within the recess; and
forming a gate electrode adjacent the gate dielectric.

### Claim 10 (depends on 9)

The method of claim 9, wherein forming the charge inducing layer comprising the polarization layer on the gallium nitride layer comprises forming the charge inducing layer comprising the polarization layer having a thickness of between about 5 nm and 10 nm.

### Claim 11 (depends on 9)

The method of claim 9, wherein forming the charge inducing layer comprises forming the polarization layer selected from the group consisting of aluminum gallium nitride, aluminum indium nitride, and indium gallium nitride.

### Claim 12 (depends on 9)

The method of claim 9, further including forming a crystal transition layer between the gallium nitride layer and the polarization layer.

### Claim 13 (depends on 12)

The method of claim 12, wherein forming the crystal transition layer comprises forming the crystal transition layer from a material selected from the group consisting of indium nitride and aluminum nitride.

### Claim 14 (depends on 9)

The method of claim 9, further including forming a gate-to-drain length between about 120 nm to about 400 nm and forming a gate-to-source length between about 5 nm to about 400 nm.

### Claim 15 (depends on 14)

The method of claim 14, wherein the gate-to-drain length is greater than the gate-to-source length.

### Claim 16

A wireless power/charging device transmission module, comprising:
a coil assembly; and
a transmitter, wherein the transmitter includes at least one n-channel gallium nitride transistor, comprising:
a gallium nitride layer;
a source structure and a drain structure formed in the gallium nitride layer;
a charge inducing layer comprising a polarization layer extending between the source structure and the drain structure;
a 2D electron gas within the gallium nitride layer; and
a gate electrode extending at least partially into the polarization layer.

### Claim 17 (depends on 16)

The wireless power/charging device transmission module of claim 16, wherein a thickness of a portion of the polarization layer which is between the gate electrode and the gallium nitride layer is less than about 1 nm.

### Claim 18 (depends on 16)

The wireless power/charging device transmission module of claim 16, further comprising a gate dielectric disposed between the gate electrode and the polarization layer.

### Claim 19 (depends on 16)

The wireless power/charging device transmission module of claim 16, further comprising a portion of the polarization layer which is between the gate electrode and the gallium nitride layer is between about 5 nm and 10 nm.

### Claim 20 (depends on 16)

The wireless power/charging device transmission module of claim 16, further including a crystal transition layer disposed between the gallium nitride layer and the polarization layer.

### Claim 21

A wireless power/charging device receiving module, comprising:
a coil assembly;
a rectifier; and
a load unit including a voltage regulator and a battery, wherein the voltage regulator includes at least one n-channel gallium nitride transistor, comprising:
a gallium nitride layer;
a source structure and a drain structure formed in the gallium nitride layer;
a charge inducing layer comprising a polarization layer extending between the source structure and the drain structure;
a 2D electron gas within the gallium nitride layer; and
a gate electrode extending at least partially into the polarization layer.

### Claim 22 (depends on 21)

The wireless power/charging device receiving module of claim 21, wherein a thickness of a portion of the polarization layer which is between the gate electrode and the gallium nitride layer is less than about 1 nm.

### Claim 23 (depends on 21)

The wireless power/charging device receiving module of claim 21, further comprising a gate dielectric disposed between the gate electrode and the polarization layer.

### Claim 24 (depends on 21)

The wireless power/charging device receiving module of claim 21, further comprising a portion of the polarization layer which is between the gate electrode and the gallium nitride layer is between about 5 nm and 10 nm.

### Claim 25 (depends on 21)

The wireless power/charging device receiving module of claim 21, further including a crystal transition layer disposed between the gallium nitride layer and the polarization layer.