Method for synthesis of high quality large area bulk gallium based crystals

• US 9,175,418 B2
• Filed: 10/11/2010
• Issued: 11/03/2015
• Est. Priority Date: 10/09/2009
• Status: Active Grant

• Current Assignee: SL Technology Incorporated (Reliv' International, Inc.)
• Original Assignee: Soraa, Inc.
• Inventors: D'Evelyn, Mark P., Speck, James S.
• Primary Examiner(s): ALANKO, ANITA KAREN
• Application Number:
  US12/988,772
• Publication Number:
  US 20110256693A1
• Time in Patent Office: 1,849 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 7/005 Epitaxial layer growth
• CPC Class Codes: C30B 7/105 using ammonia as solvent, i.e. ammonothermal processes
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02609 Crystal orientation
• CPC Class Codes: H01L 21/02645 Seed materials
• CPC Class Codes: H01L 21/02647 Lateral overgrowth
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/34 the imperfections being on the surface
• CPC Class Codes: H01L 29/36 characterised by the concentration or distribution of impurities in the bulk material within semiconductor regions H01L29/06

Abstract

A large area nitride crystal, comprising gallium and nitrogen, with a non-polar or semi-polar large-area face, is disclosed, along with a method of manufacture. The crystal is useful as a substrate for a light emitting diode, a laser diode, a transistor, a photodetector, a solar cell, or for photoelectrochemical water splitting for hydrogen generation.

Claims

1. A method for forming a gallium based crystal, comprising:

providing a bar-shaped proto-seed, the bar-shaped proto-seed comprising a gallium based crystal having a +c surface, a −

c surface and at least one surface having a crystallographic orientation within 10 degrees of an a-plane {11-20} orientation; and

subjecting the bar-shaped proto-seed to an ammonothermal growth process of a gallium based crystalline material to cause the proto-seed to grow inhomogeneously in at least one a-direction to form a gallium based crystal having at least one upper a-wing and at least one lower a-wing, wherein the upper a-wing comprises a +c surface and the upper a-wing and the lower a-wing are separated by a gap.

2. The method of claim 1, wherein the proto-seed has impurity concentrations of oxygen (O), hydrogen (H), carbon (C), sodium (Na), and potassium (K) below about 1×

10¹⁷ cm<sup>−

3</sup>, 2×

10¹⁷ cm<sup>−

3</sup>, 1×

10¹⁷ cm³, 1×

10¹⁶ cm<sup>−

3</sup>, and 1×

10¹⁶ cm<sup>−

3</sup>, respectively.

3. The method of claim 1, wherein the upper a-wing is characterized by a dislocation density below 10⁴ cm⁻

2.

4. The method of claim 1, wherein each of the upper a-wing and the lower a-wing are characterized by a dislocation density below 10⁴ cm⁻

2.

5. The method of claim 1, wherein the proto-seed is provided by removing a seed crystal structure from a thick gallium and nitrogen containing substrate made using HVPE growth or wherein the proto seed is provided by removing a seed crystal structure from a thick gallium and nitrogen containing substrate made using ammonothermal growth.

6. The method of claim 1, further comprising separating at least one a-wing from the gallium based crystal and utilizing the separated a-wing as a seed crystal for ammonothermal crystal growth.

7. The method of claim 6, wherein the ammonothermal crystal growth produces a substantially rhombus-shaped gallium-based crystal with large-area c+ and c-surfaces with a surface area of at least 25 mm², the rhombus-shaped crystal having a top surface and a bottom surface.

8. The method of claim 7, wherein the top and bottom surfaces of the substantially rhombus-shaped crystal have impurity concentrations of O, H, C, Na, and K between about 1×

10¹⁷ cm<sup>−

3</sup> and 1×

10¹⁹ cm<sup>−

3</sup>, between about 1×

10¹⁷ cm<sup>−

3</sup> and 2×

10¹⁹ cm<sup>−

3</sup>, below 1×

10¹⁷ cm<sup>−

3</sup>, below 1×

10¹⁶ cm<sup>−

3</sup>, and below 1×

10¹⁶ cm<sup>−

3</sup>, respectively.

9. The method of claim 7, wherein the top and bottom surfaces of the substantially rhombus-shaped crystal have impurity concentrations of O, H, C, and at least one of Na and K between about 1×

10¹⁷ cm<sup>−

3</sup> and 1×

10¹⁹ cm<sup>−

3</sup>, between about 1×

10¹⁷ cm³ and 2×

10¹⁹ cm<sup>−

3</sup>, below 1×

10¹⁷ cm<sup>−

3</sup>, and between about 3×

10¹⁵ cm<sup>−

3</sup> and 1×

10¹⁸ cm<sup>−

3</sup>, respectively.

10. The method of claim 7, wherein the top and bottom surfaces of the substantially rhombus-shaped crystal have impurity concentrations of O, H, C, and at least one of F and Cl between about 1×

10¹⁷ cm<sup>−

3</sup> and 1×

10¹⁹ cm<sup>−

3</sup>, between about 1×

10¹⁷ cm<sup>−

3</sup> and 2×

10¹⁹ cm<sup>−

3</sup>, below 1×

10¹⁷ cm<sup>−

3</sup>, and between about 1×

10¹⁵ cm<sup>−

3</sup> and 1×

10¹⁷ cm<sup>−

3</sup>, respectively.

11. The method of claim 7, wherein the substantially rhombus-shaped crystal has an infrared absorption peak at about 3175 cm⁻

1, with an absorbance per unit thickness of greater than about 0.01 cm<sup>−

1</sup>.

12. The method of claim 7, wherein the substantially rhombus-shaped crystal has a crystallographic radius of curvature greater than about 20 meters.

13. The method of claim 7, further comprising slicing the substantially rhombus-shaped crystal approximately parallel to a large area surface to form one or more wafers.

14. The method of claim 7, further comprising utilizing the substantially rhombus-shaped crystal or a wafer prepared therefrom as a seed crystal or substrate for further bulk crystal growth.

15. A method of manufacturing a semiconductor device, comprising utilizing a wafer prepared from the gallium-based crystal of claim 1 as a substrate for manufacture of a semiconductor structure, the semiconductor structure comprising at least one Al_xIn_yGa_(1-x-y) N epitaxial layer, where 0≦

x, y, x+y≦

1.

16. The method of claim 15, further comprising using the semiconductor structure in a gallium-nitride-based electronic device or optoelectronic device, the gallium-nitride-based electronic device or optoelectronic device being selected from a light emitting diode, a laser diode, a photodetector, an avalanche photodiode, a photovoltaic, a solar cell, a cell for photoelectrochemical splitting of water, a transistor, a rectifier, and a thyristor;

one of a transistor, a rectifier, a Schottky rectifier, a thyristor, a p-i-n diode, a metal-semiconductor-metal diode, high-electron mobility transistor, a metal semiconductor field effect transistor, a metal oxide field effect transistor, a power metal oxide semiconductor field effect transistor, a power metal insulator semiconductor field effect transistor, a bipolar junction transistor, a metal insulator field effect transistor, a heterojunction bipolar transistor, a power insulated gate bipolar transistor, a power vertical junction field effect transistor, a cascade switch, an inner sub-band emitter, a quantum well infrared photodetector, a quantum dot infrared photodetector, or combinations thereof.

17. The method of claim 7, further comprising slicing the substantially rhombus-shaped crystal into at least two laterally-grown strip-shaped crystals with at least two long edges characterized by a surface orientation within about 10 degrees of an m-plane.

18. The method of claim 17, further comprising utilizing the laterally-grown strip-shaped crystals as seeds for ammonothermal crystal growth and growing the crystals by at least 5 mm in the +/−

c direction to form a c-grown crystal.

19. A method of manufacturing a semiconductor device, comprising utilizing a wafer prepared the substantially rhombus-shaped crystal of claim 7 as a substrate for manufacture of a semiconductor structure, the semiconductor structure comprising at least one Al_xIn_yGa_(1-x-y)N epitaxial layer, where 0≦

x, y, x+y≦

1.

20. The method of claim 19, further comprising using the semiconductor structure in a gallium-nitride-based electronic device or optoelectronic device, the gallium-nitride-based electronic device or optoelectronic device being selected from a light emitting diode, a laser diode, a photodetector, an avalanche photodiode, a photovoltaic, a solar cell, a cell for photoelectrochemical splitting of water, a transistor, a rectifier, and a thyristor;

one of a transistor, a rectifier, a Schottky rectifier, a thyristor, a p-i-n diode, a metal-semiconductor-metal diode, high-electron mobility transistor, a metal semiconductor field effect transistor, a metal oxide field effect transistor, a power metal oxide semiconductor field effect transistor, a power metal insulator semiconductor field effect transistor, a bipolar junction transistor, a metal insulator field effect transistor, a heterojunction bipolar transistor, a power insulated gate bipolar transistor, a power vertical junction field effect transistor, a cascade switch, an inner sub-band emitter, a quantum well infrared photodetector, a quantum dot infrared photodetector, or combinations thereof.

21. The method of claim 1, wherein the ammonothermal growth process includes the use of polycrystalline GaN material and a mineralizer comprising at least one of fluorine (F) and chlorine (Cl).

22. The method of claim 20, wherein the ammonothermal growth process is performed at a temperature of at least 650 degrees Celsius.