Dislocation reduction in non-polar III-nitride thin films

• US 8,809,867 B2
• Filed: 09/10/2007
• Issued: 08/19/2014
• 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., Denbaars, Steven P., Speck, James S., Nakamura, Shuji
• Primary Examiner(s): Nguyen, Thinh T
• Application Number:
  US11/852,908
• Publication Number:
  US 20080135853A1
• Time in Patent Office: 2,535 Days
• Field of Search: 257/11, 257/14, 257/19, 257/347, 257/76, 257/13, 257/E29.072, 257/E21.09, 257/12, 438/507, 438/48, 438/22
• US Class Current: 257/76
• 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

Lateral epitaxial overgrowth of non-polar III-nitride seed layers reduces threading dislocations in the non-polar III-nitride thin films. First, a thin patterned dielectric mask is applied to the seed layer. Second, a selective epitaxial regrowth is performed to achieve a lateral overgrowth based on the patterned mask. Upon regrowth, the non-polar III-nitride films initially grow vertically through openings in the dielectric mask before laterally overgrowing the mask in directions perpendicular to the vertical growth direction. Threading dislocations are reduced in the overgrown regions by (1) the mask blocking the propagation of dislocations vertically into the growing film and (2) the bending of dislocations through the transition from vertical to lateral growth.

Claims

1. A III-nitride based device structure, comprising:

a Gallium Nitride (GaN) substrate;

a planar non-polar GaN film, grown on or above the GaN substrate, wherein the planar non-polar GaN film is own with a dislocation density of less than 1×

10⁸ cm<sup>−

2</sup> and a stacking fault density less than 3.8×

10⁵ cm<sup>−

1</sup>; and

a non-polar InGaN-based light emitting diode or laser diode structure, comprising a quantum well structure, grown on a surface of the planar non-polar GaN film, wherein polarization-induced electric fields are eliminated in the non-polar InGaN-based light emitting diode or laser diode structure.

2. The device structure of claim 1, wherein the film is an a-plane film.

3. The device structure of claim 1, wherein the film is an m-plane film.

12. The device of claim 1, wherein cathodoluminescence from the planar non-polar GaN film is uniform across the non-polar top surface.

4. A method of fabricating a III-nitride-based device structure, comprising:

growing a planar non-polar Gallium Nitride (GaN) film on or above a GaN substrate, wherein the planar non-polar GaN film is grown with a dislocation density of less than 1×

10⁸ cm<sup>−

2</sup> and a stacking fault density less than 3.8×

10⁵ cm<sup>−

1</sup>; and

growing a non-polar InGaN-based light emitting diode or laser diode structure, comprising a quantum well structure, on a surface of the planar non-polar GaN film, wherein polarization-induced electric fields are eliminated in the non-polar InGaN-based light emitting diode or laser diode structure.

5. The method of claim 4, wherein the film is an a-plane film.

6. The method of claim 4, wherein the film is an m-plane film.

7. The method of claim 4, further comprising:

(a) depositing a dielectric regrowth mask on a non-polar GaN layer on the GaN substrate;

(b) patterning the deposited mask; and

(c) performing a selective regrowth to achieve an overgrowth based on the patterned mask, wherein the overgrowth comprises the planar non-polar GaN film.

8. The method of claim 7, wherein the overgrowth comprises a lateral epitaxial overgrowth.

9. The method of claim 7, wherein the dislocations are reduced in the overgrowth by the mask blocking propagation of the dislocations vertically into the growing film.

10. The method of claim 7, wherein the dislocations are reduced in the overgrowth by bending of the dislocations through a transition from vertical to lateral growth.

11. The method of claim 4, wherein cathodoluminescence from the planar non-polar GaN film is uniform across the non-polar top surface.