Thick pseudomorphic nitride epitaxial layers

Patent metadata

Field	Value
Publication number	US-9437430-B2
Application number	US-2000608-A
Country	US
Kind code	B2
Filing date	Jan 25, 2008
Priority date	Jan 26, 2007
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

Semiconductor structures are fabricated to include strained epitaxial layers exceeding a predicted critical thickness thereof.

First claim

What is claimed is:

1. A semiconductor heterostructure comprising:
an aluminum nitride single-crystal substrate; and
at least one strained layer epitaxially grown thereover, the layer comprising at least one of AlN, GaN, InN, or any binary or tertiary alloy combination thereof,
wherein a thickness of the strained layer exceeds a predicted critical thickness associated therewith by at least a factor of 5, as calculated with the Matthews-Blakeslee theory,

h
c

=

b

8
⁢
π
⁢

⁢
f

⁢

(

1
-

v
⁢

⁢

cos
2

⁢
α

)

(

1
+
v

)

⁢
cos
⁢

⁢
λ

⁢

(

ln
⁡

(

h
c

b

)

+
1

)

,

where h c is the predicted critical thickness, b is the magnitude of the Burgers vector of a dislocation formed between the layer and the substrate, f is the lattice mismatch between the layer and the substrate, υ is the Poisson's ratio of the layer, λ is the angle between the slip direction of the layer and the direction in the plane of the layer perpendicular to the line of intersection of the slip plane of the layer and the interface between the layer and the substrate, and α is the angle between the dislocation and the Burgers vector of the dislocation.

2. The semiconductor heterostructure of claim 1 , wherein the thickness of the at least one strained layer exceeds the predicted critical thickness by at least a factor of 10.

3. The semiconductor heterostructure of claim 1 , wherein the at least one strained layer is substantially free of In.

4. The semiconductor heterostructure of claim 1 , wherein the at least one strained layer has a density of macroscopic defects less than approximately 1 mm −2 .

5. The semiconductor heterostructure of claim 1 , wherein a strain parallel to the at least one strained layer is greater than 80% of a difference between parallel lattice parameters of an unstrained alloy of the same composition as the at least one strained layer and a relaxed platform disposed beneath the at least one strained layer.

6. The semiconductor heterostructure of claim 5 , wherein the at least one strained layer comprises Al x Ga 1-x N, the thickness of the at least one strained layer is greater than approximately 200 nm, and x is less than approximately 0.65.

7. The semiconductor heterostructure of claim 1 , wherein the thickness of the at least one strained layer is greater than approximately 1 μm.

8. The semiconductor heterostructure of claim 1 , wherein the at least one strained layer has an average threading dislocation density less than approximately 10,000 cm −2 .

9. A method for forming a semiconductor heterostructure, the method comprising:
providing an aluminum nitride single-crystal substrate; and
epitaxially depositing over the substrate a strained layer comprising at east one of AlN, GaN, InN, or any binary or tertiary alloy combination thereof,
wherein a thickness of the strained layer exceeds a predicted critical thickness associated therewith by at least a factor of 5, as calculated with the Matthews-Blakeslee theory,

h
c

=

b

8
⁢
π
⁢

⁢
f

⁢

(

1
-

v
⁢

⁢

cos
2

⁢
α

)

(

1
+
v

)

⁢
cos
⁢

⁢
λ

⁢

(

ln
⁡

(

h
c

b

)

+
1

)

,

where h c is the predicted critical thickness, b is the magnitude of the Burgers vector of

Assignees

• Schowalter Leo J
• Smart Joseph A
• Grandusky James R
• Liu Shiwen
• Crystal Is Inc

Inventors

• Schowalter Leo J
• Smart Joseph A
• Grandusky James R
• Liu Shiwen

Classifications

• H10P14/3416

  Nitrides · CPC title

• H10P14/3254

  Graded layers · CPC title

• H10P14/3216

  Nitrides · CPC title

• H10P14/2926

  Crystal orientations · CPC title

• H10P14/2925

  Surface structures · CPC title