Method for heteroepitaxial growth of high-quality N-face gallium nitride, indium nitride, and aluminum nitride and their alloys by metal organic chemical vapor deposition

• US 8,455,885 B2
• Filed: 04/11/2012
• Issued: 06/04/2013
• Est. Priority Date: 11/15/2006
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Keller, Stacia, Mishra, Umesh K., Fichtenbaum, Nicholas A.
• Primary Examiner(s): MULPURI, SAVITRI
• Application Number:
  US13/444,011
• Publication Number:
  US 20120193638A1
• Time in Patent Office: 419 Days
• Field of Search: 257/79, 257/103
• US Class Current: 257/79
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02538 Group 13/15 materials
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02573 Conductivity type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD

Abstract

Methods for the heteroepitaxial growth of smooth, high quality films of N-face GaN film grown by MOCVD are disclosed. Use of a misoriented substrate and possibly nitridizing the substrate allow for the growth of smooth N-face GaN and other Group III nitride films as disclosed herein. The present invention also avoids the typical large (μm sized) hexagonal features which make N-face GaN material unacceptable for device applications. The present invention allows for the growth of smooth, high quality films which makes the development of N-face devices possible.

Claims

1. A device structure, comprising:

a substrate having a growth surface, wherein the growth surface has a misorientation angle relative to a miller indexed crystallographic plane [h, i, k, l] of the substrate, where h, i, k, l are miller indices;

a Ga-polar Gallium Nitride (GaN) layer on the growth surface;

a transition layer on the Ga-polar GaN layer, wherein the transition layer sets an N-polar [000-1] orientation for one or more subsequent layers formed on the layer; and

one or more N-polar group III-nitride layers on the transition layer, wherein;

the N-polar group III-nitride layers include a GaN layer,

the N-polar group III-nitride layers have the N-polar [000-1] orientation set by the transition layer, and

the N-polar group III-nitride layers have a top surface that is smooth with a root mean square surface roughness of no more than 2 nanometers over an area of at least 10 micrometers by 10 micrometers.

2. The device structure of claim 1, wherein the misorientation angle is between 0.5 and 10 degrees.

3. The device structure of claim 1, wherein the transition layer is doped with magnesium.

4. The device structure of claim 1, wherein the miller indices are h=1, i=0, k=0 and l=−

1 and the substrate is silicon carbide.

5. The device structure of claim 1, wherein the miller indices are h=0, i=0, k=0 and l=1 and the substrate is sapphire.

6. The device structure of claim 1, wherein the miller indices are h=1, k=1, l=1 and the substrate is silicon.

7. The device structure of claim 1, wherein the substrate is (001) Si.

8. The device structure of claim 1, wherein:

the N-polar group III-nitride layers are doped or undoped to form a device structure for an N-face transistor or light emitting device,

a surface of the transition layer adjacent to the N-polar group III-nitride layers results in the N-polar group III-nitride layers grown on top of the transition layer having the N-polar [000-1] orientation.

9. The device structure of claim 8, wherein the light emitting device has an N-face surface roughened for light extraction.

10. The device structure of claim 1, wherein a portion of the transition layer adjacent to a first surface of the transition layer is Ga-polar and a portion of the transition layer adjacent to a second surface of the transition layer is N-polar.

11. The device structure of claim 10, wherein:

the first surface is adjacent to the Ga-polar Gallium Nitride layer,

and the second surface is adjacent to the N-polar group III-nitride layers.

12. The device structure of claim 1, further comprising a nitride layer on the growth surface and between the substrate and the N-polar group III-nitride layers, wherein an orientation of the nitride layer is different from an N-polar orientation.

13. The device structure of claim 1, wherein the substrate is a nitridized misoriented substrate.

14. The device structure of claim 1, wherein an atomic structure of a surface of the transition layer adjacent to the N-polar group III-nitride layers results in the N-polar group III-nitride layers, grown on top of the transition layer, having the N-polar [000-1] orientation.

15. The device structure of claim 1, wherein:

at least one of the N-polar group III-nitride layers includes a channel of the device structure,

at least one of the N-polar group III-nitride layers is a misoriented N-face layer, and

the channel is oriented, with respect to a misorientation direction of the misoriented N-face layer.

18. The device structure of claim 1, wherein the N-polar group III-nitride layers have a threading dislocation density of at most on an order of 10⁹ cm⁻

2.

16. A method for fabricating an N-polar group III-nitride device structure, comprising:

obtaining a growth surface of a substrate, wherein the growth surface has a misorientation angle relative to a miller indexed crystallographic plane [h, i, k, l] of the substrate, where h, i, k, l are miller indices;

forming a Ga-polar Gallium Nitride (GaN) layer on the growth surface;

forming a transition layer on the Ga-polar GaN layer, wherein the transition layer sets an N-polar [000-1] orientation for one or more subsequent layers formed on the transition layer; and

growing one or more N-polar group III-nitride layers on the transition layer, wherein;

the N-polar group III-nitride layers include a GaN layer

the N-polar group III-nitride layers have the N-polar [000-1] orientation set by the transition layer, and

the N-polar group III-nitride layers have a top surface that is smooth with a root mean square surface roughness of no more than 2 nanometers over an area of at least 10 micrometers by 10 micrometers.

17. The method of claim 16, further comprising doping the transition layer with magnesium.

19. A device structure, comprising:

a substrate having a growth surface, wherein the growth surface has a misorientation angle relative to a miller indexed crystallographic plane [h, i, k, 1] of the substrate, where h, i, k,1 are miller indices; and

a group III-N transition layer on or above the growth surface, wherein;

the group III-N transition layer sets an N-polar [000-1] orientation for one or more subsequent layers formed on the layer, and

a portion of the group III-N transition layer adjacent the growth surface is Ga-polar; and

one or more N-polar group III-nitride layers on the group III-N transition layer, wherein the N-polar group III-nitride layers have the N-polar [000-1] orientation set by the group III-N transition layer.

20. A device structure, comprising:

a substrate comprising sapphire, silicon, or SiC, the substrate having a growth surface, wherein the growth surface has a misorientation angle relative to a miller indexed crystallographic plane of the substrate;

a Ga-polar Gallium Nitride (GaN) layer on the growth surface;

a transition layer on the Ga-polar GaN layer, wherein the transition layer sets an N-polar [000-1] orientation for one or more subsequent layers formed on the transition layer; and

one or more N-polar group III-nitride layers on the transition layer, wherein the one or more N-polar group III-nitride layers have the N-polar [000-1]orientation set by the transition layer and the one or more N-polar group III-nitride layers include a GaN layer.