# US 7,465,967 B2 · Group III nitride field effect transistors (FETS) capable of withstanding high temperature reverse bias test conditions

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- Number: US 7,465,967 B2
- Document ID: US7465967B2
- Status: Granted
- Kind: B2
- Application number: 11/080,905
- Filed: 2005-03-15
- Published: 2006-09-21
- Granted: 2008-12-16
- Earliest claimed: 2005-03-15
- Assignees: Cree, Inc.
- Inventors: Richard Peter Smith; Scott T. Sheppard; Adam William Saxler; Yifeng Wu
- Web page: https://patentgrep.com/patent/US7465967B2

## CPC

- H10D 84/01: Manufacture or treatment
- H10D 30/4755: {having wide bandgap charge-carrier supplying layers, e.g. modulation doped HEMTs such as n-AlGaAs/GaAs HEMTs}
- H10D 84/05: using Group III-V technology
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 62/854: further characterised by the dopants
- H10D 64/411: {for FETs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Group III Nitride based field effect transistor (FETS) are provided having a power degradation of less than about 3.0 dB when operated at a drain-to-source voltage (VDS) of about 56 volts, a gate to source voltage (Vgs) of from about −8 to about −14 volts and a temperature of about 140° C. for at least about 10 hours.

## Claims

### Claim 1

A Group III Nitride based field effect transistor (FET) having a power degradation of less than about 3.0 dB when operated at a drain-to-source voltage (VDS) of about 56 volts, a gate to source voltage (Vgs)) of from about −8 to about −14 volts and a temperature of about 140° C. for at least about 10 hours.

### Claim 2 (depends on 1)

The FET of claim 1 having a power degradation of not greater than about 0.44 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts and a temperature of about 140° C. for about 20 hours.

### Claim 3 (depends on 2)

The FET of claim 2, comprising a GaN channel layer having a thickness of about 2.0 μm.

### Claim 4 (depends on 3)

The FET of claim 3, wherein the FET is a high electron mobility transistor (HEMT) and wherein the HEMT further comprises:
an ALN layer on the GaN channel layer;
an AlGaN layer on the AlN layer;
a T- gate contact on the AlGaN layer;
an insulating layer on a surface of the HEMT; and
source and drain contacts on the AlGaN layer.

### Claim 5 (depends on 4)

The FET of claim 4 having a power density of greater than about 3.0 W/mm operating at a frequency of from about 3.5 to about 4.0 GHz.

### Claim 6 (depends on 3)

The FET of claim 3, wherein a distance from the T-gate contact to the source contact is about 0.7 μm, wherein a distance from the T-gate contact to the drain contact is about 2.0 μm, wherein a length of a T portion of the gate contact is about 0.7 μm and wherein a length of a base of the T-gate contact is about 0.2 μm.

### Claim 7 (depends on 6)

The FET of claim 6, wherein a distance wings of the T-gate contact extend out from the base of the T-gate contact about 0.25 μm.

### Claim 8 (depends on 2)

The FET of claim 2, comprising a GaN channel layer having a thickness of from about 2.0 μm to about 8.0 μm and wherein all but about 1.0 μm of a surface of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2 ×1018 cm−3.

### Claim 9 (depends on 8)

The FET of claim 8, wherein the FET is a high electron mobility transistor (HEMT) and wherein the HEMT further comprises:
an AlN layer on the GaN channel layer;
an AlGaN layer on the AlN layer;
a T- gate contact on the AlGaN layer;
an insulating layer on a surface of the HEMT; and
source and drain contacts on the AlGaN layer.

### Claim 10 (depends on 9)

The FET of claim 9 having a power density of greater than about 3.0 W/mm operating at a frequency of from about 3.5 to about 4.0 GHz.

### Claim 11 (depends on 1)

The FET of claim 1 having a power degradation of not greater than about 1.3 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts and a temperature of about 140° C. for about 20 hours.

### Claim 12 (depends on 1)

The FET of claim 1 having a power degradation of not greater than about 0.25 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts and a temperature of about 140° C. for about 10 hours.

### Claim 13 (depends on 12)

The FET of claim 12, comprising a passivation layer on a surface of the FET, the passivation layer including silicon nitride (SiN).

### Claim 14 (depends on 13)

The FET of claim 13, wherein the FET is a high electron mobility transistor (HEMT) and wherein the HEMT further comprises:
a GaN channel layer;
an AlN layer on the GaN channel layer;
an AlGaN layer on the AlN layer;
a T- gate contact on the AlGaN layer; and
source and drain contacts on the AlGaN layer, wherein the passivation layer is provided on the T-gate contact, the AlGaN layer and the source and drain contacts.

### Claim 15 (depends on 14)

The FET of claim 14 having a power density of greater than about 3.0 W/mm operating at a frequency of from about 3.5 to about 4.0 GHz.

### Claim 16 (depends on 1)

The FET of claim 1 having a power degradation of not greater than about 0.40 dB when operated at a VDS of about 56 volts, a Vgs of from about −8 volts to about −14 volts and a temperature of about 140° C. for from about 10 to about 62 hours.

### Claim 17 (depends on 16)

The FET of claim 16, comprising a GaN channel layer having a thickness of about 6.0 μm and wherein all but about 1.0 μm of a surface of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2×1018 cm−3.

### Claim 18 (depends on 17)

The FET of claim 17, wherein the FET is a high electron mobility transistor (HEMT) and wherein the HEMT further comprises:
an AlN layer on the GaN channel layer;
an AlGaN layer on the AlN layer;
a T- gate contact on the AlGaN layer;
an insulating layer on a surface of the HEMT; and
source and drain contacts on the AlGaN layer.

### Claim 19 (depends on 18)

The FET of claim 18 having a power density of greater than about 3.0 W/mm operating at a frequency of from about 3.5 to about 4.0 GHz.

### Claim 20 (depends on 1)

The FET of claim 1 having a power degradation not greater than about 1.0 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts to and a temperature of about 140° C. for about 10 hours.

### Claim 21 (depends on 20)

The FET of claim 20, comprising:
a GaN channel layer having a thickness of about 6.0 μm; and
an AlGaN layer on the GaN channel layer, having from about 15 to about 30 percent Al and a thickness of from about 15 to about 40 nm.

### Claim 22 (depends on 21)

The FET of claim 21, wherein the FET is a high electron mobility transistor (HEMT) and wherein the HEMT further comprises:
an AlN layer between the GaN channel layer and the AlGaN;
a T- gate contact on the AlGaN layer;
an insulating layer on a surface of the HEMT; and
source and drain contacts on the AlGaN layer.

### Claim 23 (depends on 22)

The FET of claim 22 having a power density of greater than about 3.0 W/mm operating at a frequency of from about 3.5 to about 4.0 GHz.

### Claim 24 (depends on 1)

The FET of claim 1 having a power degradation of not greater than about 0.45 dB when operated at a VDS of from about 28 to about 70 volts, a Vgs of about −3.3 to about −14 and a temperature of about 140° C. for about 6 to about 100 hours.

### Claim 25 (depends on 24)

The FET of claim 24, comprising a GaN channel layer having a thickness of about 6.0 μm and wherein all but about 1.0 μm of a surface of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2×1018 cm−3.

### Claim 26 (depends on 25)

The FET of claim 25, wherein the FET is a high electron mobility transistor (HEMT) and wherein the HEMT further comprises:
an AlN layer on the GaN channel layer;
an AlGaN layer on the AlN layer;
a T- gate contact on the AlGaN layer;
an insulating layer on a surface of the HEMT; and
source and drain contacts on the AlGaN layer.

### Claim 27 (depends on 26)

The FET of claim 26 having a power density of greater than about 3.0 W/mm operating at a frequency of from about 3.5 to about 4.0 GHz.

### Claim 28

A Group III Nitride based field effect transistor (FET) capable of withstanding high temperature, reverse bias test conditions of a drain-to-source voltage (VDS) of about 56 volts, a gate to source voltage (Vgs)) of from about −8 to about −14 volts and a temperature of about 140° C. for at least about 10 hours.

### Claim 29 (depends on 28)

The FET of claim 28 having a power density of greater than about 3.0 W/mm operating at a frequency of from about 3.5 to about 4.0 GHz.

### Claim 30 (depends on 28)

The FET of claim 28, wherein the FET comprises a high electron mobility transistor (HEMT) and wherein the HEMT further comprises:
a GaN Channel layer;
an AlN layer on the GaN channel layer;
an AlGaN layer on the AlN layer;
a T- gate contact on the AlGaN layer;
an insulating layer on a surface of the HEMT; and
source and drain contacts on the AlGaN layer.

### Claim 31 (depends on 30)

The FET of claim 30, wherein the GaN channel layer has a thickness of about 2.0 μm.

### Claim 32 (depends on 30)

The FET of claim 30, wherein the GaN channel layer has a thickness of from about 2.0 μm to about 8.0 μm and wherein all but about 1.0 μm of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2×1018 cm−3.

### Claim 33 (depends on 30)

The FET of claim 30, wherein the insulating layer comprises a passivation layer including silicon nitride (SiN).

### Claim 34 (depends on 30)

The FET of claim 30, wherein the GaN channel layer has a thickness of about 6.0 μm and wherein about 5.0 μm of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2×1018 cm−3.

### Claim 35 (depends on 30)

The FET of claim 30, wherein the GaN channel layer has a thickness of about 6.0 μm and wherein the AlGaN layer has from about 15 to about 30 percent Al and a thickness of from about 15 to about 40 nm.

### Claim 36

A high electron mobility transistor (HEMT) having a power degradation of less than about 3.0 dB and a power density of greater than about 3.0 W/mm when operated at a drain-to-source voltage (VDS) of about 56 volts, a gate to source voltage (Vgs)) of from about −8 to about −14 volts and a temperature of about 140° C. for at least about 10 hours.

### Claim 37 (depends on 36)

The HEMT of claim 36 having a power degradation of not greater than about 0.44 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts and a temperature of about 140° C. for about 20 hours, wherein the HEMT comprises a GaN channel layer having a thickness of about 2.0 μm.

### Claim 38 (depends on 36)

The HEMT of claim 36 having a power degradation of not greater than about 1.3 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts and a temperature of about 140° C. for about 20 hours, wherein the HEMT comprises a GaN channel layer having a thickness of from about 2.0 μm to about 8 μm and wherein all but about 1.0 μm of a surface of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2×1018 cm−3.

### Claim 39 (depends on 36)

The HEMT of claim 36 having a power degradation of not greater than about 0.25 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts and a temperature of about 140° C. for about 10 hours, wherein the HEMT comprises a passivation layer on a surface of the HEMT, the passivation layer including silicon nitride (SiN).

### Claim 40 (depends on 36)

The HEMT of claim 36 having a power degradation of not greater than about 0.40 dB when operated at a VDS of about 56 volts, a Vgs of from about −8 volts to about −14 volts and a temperature of about 140° C. for from about 10 to about 62 hours, the HEMT comprising a GaN channel layer having a thickness of about 6.0 μm and wherein about but about 1.0 μm of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2×1018 cm−3.

### Claim 41 (depends on 36)

The HEMT of claim 36, having a power degradation of not greater than about 0.25 dB when operated at a VDS of about 56 volts, a Vgs of about −8 volts to and a temperature of about 140° C. for about 10 hours, wherein the HEMT comprises:
a GaN channel layer having a thickness of about 6.0 μm; and
an AlGaN layer on the GaN channel layer, having from about 15 to about 30 percent Al and a thickness of from about 15 to about 40 nm.

### Claim 42 (depends on 36)

The HEMT of claim 36 having a power degradation of not greater than about 0.45 dB when operated at a VDS of from about 28 to about 70 volts, a Vgs of about −3.3 to about −14 and a temperature of about 140° C. for about 6 to about 100 hours, wherein the HEMT comprises a GaN channel layer having a thickness of about 6.0 μm and wherein all but about 1.0 μm of the GaN channel layer is doped with Fe to a concentration of from about 2×1016 cm−3 to about 2×1018 cm−3.