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

• US 10,100,425 B2
• Filed: 11/02/2015
• Issued: 10/16/2018
• Est. Priority Date: 10/09/2009
• Status: Active Grant

• Current Assignee: SL Technology Incorporated (Reliv' International, Inc.)
• Original Assignee: SL Technology Incorporated (Reliv' International, Inc.)
• Inventors: D'Evelyn, Mark P., Speck, James S.
• Primary Examiner(s): Bergner, Erin F
• Application Number:
  US14/930,170
• Publication Number:
  US 20160053400A1
• Time in Patent Office: 1,079 Days
• 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 gallium based seed crystal, wherein

the gallium based seed crystal comprises at least one of a +c-plane surface and a −

c-plane surface, and

at least one of the +c-plane surface and the −

c-plane surface is bounded by four m-plane edges; and

subjecting the gallium based seed crystal to an ammonothermal growth process to cause the gallium based seed crystal to grow in at least one of a +c direction and a −

c direction by at least about 5 mm to form a c-grown gallium based crystal comprising at least four m-plane surfaces and at least one ±

c-plane surface, wherein

at least two of the at least four m-plane surfaces of the c-grown gallium based crystal each have an area larger than the at least one ±

c-plane surface of the c-grown gallium based crystal.

2. The method of claim 1, wherein each of the at least one of the +c-plane surface and the −

c-plane surface of the gallium based seed crystal has a length that is parallel to at least one of the four m-plane edges and is perpendicular to a width, and

the length is larger than the width by a factor of 5 or more.

3. The method of claim 1, wherein the c-grown gallium based crystal has 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.

4. The method of claim 1, wherein the c-grown gallium based crystal has 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 cm<sup>−

3</sup> 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.

5. The method of claim 1, wherein the c-grown gallium based crystal has 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.

6. The method of claim 1, wherein the c-grown gallium based crystal is characterized by a FWHM of a 1-100 x-ray rocking curve of at least one of the at least four m-plane surfaces below 50 arcsec, a dislocation density on at least one large-area m-plane surface below 10⁶ cm⁻

2, and a dislocation density through a c-plane in the c-grown gallium based crystal below about 10⁵ cm<sup>−

2</sup>.

7. The method of claim 1, wherein the c-grown gallium based 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>.

8. The method of claim 1, wherein the c-grown gallium based crystal has a crystallographic radius of curvature greater than about 20 meters.

9. The method of claim 1, further comprising slicing the c-grown gallium based crystal approximately substantially parallel to a large area surface to form one or more wafers.

10. The method of claim 1, further comprising utilizing the c-grown gallium based crystal or a wafer prepared therefrom as a seed crystal or substrate for further bulk crystal growth.

11. The method of claim 9, wherein the one or more wafers comprise 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.

12. The method of claim 11, 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, a thyristor, a Schottky rectifier, 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.

13. The method of claim 1, wherein the c-grown gallium based crystal comprises at least two semipolar {10-11} surfaces and at least two semipolar {10-1-1} surfaces, wherein the total area of the at least two semipolar {10-1-1} surfaces is larger, by a factor of at least 1.5, than the total area of the at least two semipolar {10-11} surfaces.

14. 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).

15. The method of claim 1, wherein the ammonothermal growth process is performed at a temperature of at least 650 degrees Celsius.

16. The method of claim 10, further comprising

preparing one or more wafers from the seed crystal formed by the further bulk crystal growth.

17. The method of claim 10, wherein the further bulk crystal growth comprises HVPE growth.

18. The method of claim 1, wherein the gallium based seed is prepared by a process using a c-plane GaN layer that was formed on a sapphire or gallium arsenide substrate, with a thickness of at least 1 mm.

19. The method of claim 16, wherein the one or more wafers comprise 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. A method for forming a gallium based crystal, comprising:

providing a first gallium based seed crystal, wherein

the first gallium based seed crystal comprises at least one of a +c-plane surface and a −

c-plane surface, has a length along at least one of the edges of the +c-plane surface or the −

c plane surface that is larger than a width that is perpendicular to the length by a factor of 5 or more, and was prepared from a gallium-based crystal that was grown by an ammonothermal process in at least one a-direction on a second gallium based seed crystal having a maximum dimension in an m-direction that is greater than a maximum dimension in one of a +c and a −

c directions; and

subjecting the first gallium based seed crystal to an ammonothermal growth process to cause the gallium based seed crystal to grow in the at least one of the +c and the −

c directions by at least about 5 mm to form a c-grown gallium based crystal comprising at least four m-plane surfaces and at least one ±

c-plane surfaces, wherein two of the at least four m-plane surfaces each have an area larger than each of the at least one ±

c-plane surfaces.