Non-polar gallium nitride thin films grown by metalorganic chemical vapor deposition

• US 9,039,834 B2
• Filed: 06/02/2011
• Issued: 05/26/2015
• Est. Priority Date: 04/15/2002
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Craven, Michael D., Speck, James Stephen
• Primary Examiner(s): SONG, MATTHEW J
• Application Number:
  US13/151,491
• Publication Number:
  US 20110229639A1
• Time in Patent Office: 1,454 Days
• Field of Search: 117/84, 117/88, 117/89, 117/90, 117/93, 117/94, 117/102, 117/104, 117/105, 117/106, 117/952
• US Class Current: 117/106
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/04 Pattern deposit, e.g. by using masks
• CPC Class Codes: C30B 25/105 by irradiation or electric discharge
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 29/605 Products containing multiple oriented crystallites, e.g. columnar crystallites
• CPC Class Codes: H01L 21/0237 Materials
• 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 21/0254 Nitrides
• CPC Class Codes: H01L 21/02609 Crystal orientation
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02639 Preparation of substrate for selective deposition
• CPC Class Codes: H01L 21/02647 Lateral overgrowth

Abstract

Non-polar (11 20) a-plane gallium nitride (GaN) films with planar surfaces are grown on (1 102) r-plane sapphire substrates by employing a low temperature nucleation layer as a buffer layer prior to a high temperature growth of the non-polar (11 20) a-plane GaN thin films.

Claims

1. A method of growing non-polar Gallium Nitride (GaN), comprising:

growing GaN, including a non-polar a-plane GaN film, on an r-plane of a sapphire substrate using metalorganic chemical vapor deposition (MOCVD) and growth conditions including growth temperature, growth pressure, and a V/III ratio, including;

(a) depositing a GaN layer on the r-plane sapphire substrate at a first growth temperature between 400°

C. and 900°

C. and at atmospheric pressure; and

(b) growing the non-polar a-plane GaN film on the GaN layer at a growth pressure of 0.2 atmospheres or less, at the growth temperature higher than the first growth temperature, and using a V/III ratio of ˜

1300, wherein;

the non-polar a-plane GaN film has;

a crystalline quality characterized by an on-axis Omega rocking curve having a full-width half-maximum (FWHM) of no more than 0.29°

(1037″

) and an off-axis Omega rocking curve having a FWHM of no more than 0.46°

(1659″

),

a threading dislocation density of no more than 2.6×

10¹⁰ cm<sup>−

2</sup>,

a threading dislocation line direction parallel to a film normal of the non-polar a-plane GaN film,

stacking faults aligned perpendicular to a c-axis of the non-polar a-plane GaN film with a stacking fault density of no more than 3.8×

10⁵ cm<sup>−

1</sup>,

a top surface with a surface roughness of no more than 2.6 nanometers (nm) over an area of 5 micrometers by 5 micrometers, and

surface pitting on a sub-micron scale with a density within an order of magnitude of the threading dislocation density.

2. The method of claim 1, wherein the non-polar a-plane GaN film comprises a coalesced film and has a wurtzite structure.

3. The method of claim 1, wherein the non-polar a-plane GaN film has a planar top surface.

4. The method of claim 1, wherein the non-polar a-plane GaN film is suitable for subsequent growth of device-quality III-nitride layers.

5. The method of claim 1, wherein the non-polar a-plane GaN film has a top surface that is a device substrate or base for subsequent growth of non-polar III-nitride device layers on the top surface of the non-polar a-plane GaN film.

6. The method of claim 1, wherein the GaN layer is

a nucleation and/or buffer layer.

7. The method of claim 1, wherein

the growth temperature for the non-polar a-plane GaN film is about 1100°

C.

8. The method of claim 1, wherein the growth conditions and the substrate obtain the non-polar a-plane GaN film having no c-plane content.

9. The method of claim 1, wherein the stacking fault density is at the top surface.

10. The method of claim 1, wherein the growth conditions obtain the non-polar a-plane GaN film with a stable a-plane orientation.

11. The method of claim 1, wherein the non-polar a-plane GaN film includes a thickness of 1.5 micrometers.

12. The method of claim 11, wherein the GaN layer is a buffer layer and/or nucleation layer having at thickness of 1-100 nanometers.

13. The method of claim 1, wherein growing the non-polar a-plane GaN film includes using 30 μ

mol per minute Ga flow and 40,000 μ

mol per minute N flow, thereby providing a VIII ratio of approximately 1300.