Method for growing β phase of gallium oxide ([β]-Ga2O3) single crystals from the melt contained within a metal crucible

Patent metadata

Field	Value
Publication number	US-11028501-B2
Application number	US-201515541764-A
Country	US
Kind code	B2
Filing date	Dec 16, 2015
Priority date	Jan 9, 2015
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A method for growing beta phase of gallium oxide (β-Ga2O3) single crystals from the melt contained within a metal crucible surrounded by a thermal insulation and heated by a heater. A growth atmosphere provided into a growth furnace has a variable oxygen concentration or partial pressure in such a way that the oxygen concentration reaches a growth oxygen concentration value (C2, C2′, C2″) in the concentration range (SC) of 5-100 vol. % below the melting temperature (MT) of Ga2O3 or at the melting temperature (MT) or after complete melting of the Ga2O3 starting material adapted to minimize creation of metallic gallium amount and thus eutectic formation with the metal crucible. During the crystal growth step of the β-Ga2O3 single crystal from the melt at the growth temperature (GT) the growth oxygen concentration value (C2, C2′, C2″) is maintained within the oxygen concentration range (SC).

First claim

The invention claimed is:

1. A method for growing beta phase of gallium oxide (β-Ga 2 O 3 ) single crystals from a melt contained within a metal crucible, comprising the steps of:
providing into a growth chamber a thermal system or growth furnace ( 100 , 200 , 300 , 400 , 500 , 600 ) comprising the metal crucible ( 101 , 201 , 301 , 401 , 501 , 601 ) containing the Ga 2 O 3 starting material ( 102 , 202 , 302 , 402 , 502 , 602 ), a thermal insulation ( 103 , 203 , 303 , 403 , 503 , 603 ) surrounding the metal crucible ( 101 , 201 , 301 , 401 , 501 , 601 ) and a heater ( 104 , 204 , 304 , 404 , 504 , 604 ) disposed around the metal crucible ( 101 , 201 , 301 , 401 , 501 , 601 );
providing or creating a crystal seed ( 105 , 205 , 305 , 405 , 505 , 605 ) within the growth furnace ( 100 , 200 , 300 , 400 , 500 , 600 );
introducing at least into the growth furnace ( 100 , 200 , 300 , 400 , 500 , 600 ) a growth atmosphere ( 120 , 220 , 320 , 420 , 520 , 620 ) containing oxygen;
heating up the metal crucible ( 101 , 201 , 301 , 401 , 501 , 601 ) by the heater ( 104 , 204 , 304 , 404 , 504 , 604 ), which in turns heats up the Ga 2 O 3 starting material ( 102 , 202 , 302 , 402 , 502 , 602 ) until melting;
contacting the crystal seed ( 105 , 205 , 305 , 405 , 505 , 605 ) with the molten Ga 2 O 3 starting material ( 102 , 202 , 302 , 402 , 502 , 602 ) contained within the metal crucible ( 101 , 201 , 301 , 401 , 501 , 601 );
growing a β-Ga 2 O 3 single crystal ( 110 , 210 , 310 , 410 , 510 , 610 ) on the crystal seed ( 105 , 205 , 305 , 405 , 505 , 605 ) by temperature gradients between the crystal seed and the melt;
cooling down the grown β-Ga 2 O 3 single crystal ( 110 , 210 , 310 , 410 , 510 , 610 ) to room temperature (RT) once the crystal growth step has been completed;

characterized in that it further comprises the steps of:
i) providing into the growth furnace ( 100 , 200 , 300 , 400 , 500 , 600 ) the growth atmosphere ( 120 , 220 , 320 , 420 , 520 , 620 ) consisting of a mixture of pure oxygen and at least one non-reducing gas selected from the group consisting of Ar, N 2 , He Xe, Ne, and CO 2 , with a variable oxygen concentration (OC) or partial pressure at substantially atmospheric pressure in such a way that the oxygen concentration (OC) reaches a growth oxygen concentration value (C 2 , C 2 ′, C 2 ″) in the concentration range (SC) of 5-100 vol. % below ( 8 , 9 ) the melting temperature (MT) of Ga 2 O 3 or at ( 6 , 7 ) the melting temperature (MP) or after ( 5 ) complete melting of the Ga 2 O 3 starting material ( 102 , 202 , 302 , 402 , 502 , 602 ) adapted to minimize creation of metallic gallium amount (CR 1 , CR 2 , CR 3 ) and thus eutectic formation with the metal crucible ( 101 , 201 , 301 , 401 , 501 , 601 ) and to improve stoichiometry of the Ga 2 O 3 starting material ( 102 , 202 , 302 , 402 , 502 , 602 ) and crystal growth stability; and
ii) maintaining the growth oxygen concentration value (C 2 , C 2 ′, C 2 ″) within the oxygen concentration range (SC) during the crystal growth step of the β-Ga 2 O 3 single crystal ( 110 , 210 , 310 , 410 , 510 , 610 ) from the melt at the growth temperature (GT).

2. The method according to claim 1 , wherein the oxygen concentration (OC):
iii) does not exceed an intermediate oxygen concentration value (C 1 ) in the range of 0-5 vol. % during the heating up step from room temperature (RT) to an intermediate temperature value (T 1 ), intermediate temperature value (T 1 ) being located within the temperature range (ST) between 1000° C. and the melting temperature (MT) of Ga 2 O 3 ;
iv) increases from the intermediate oxygen concentration value (C 1 ) to the growth oxygen concentration value (C 2 , C 2 ′, C 2 ″) in the oxygen concentration range (SC) of 5-100 vol. % during the heating up step from the intermediate temperature value (T 1 ) to the melting temperature (MT) of Ga 2 O 3 or at the melting temperature (MT) or after complete melting of the Ga 2 O 3 starting material ( 102 , 202 , 302 , 402 , 502 , 602 ) if the intermediate temperature value (T 1 ) substantially equals to the melting temperature (MT).

3. The method according to claim 1 , wherein the oxygen concentration (OC):
v) decreases from the growth oxygen concentration value (C 2 , C 2 ′, C 2 ″) to a final oxygen concentration value (C 3 ) being lower than the growth oxygen concentration value (C 2 , C 2 ′, C 2 ″) during the cooling down step from the growth temperature (GT) to room temperature (RT).

4. The method according to claim 1 , wherein the growth oxygen concentration value (C 2 ) is substantially constant ( 10 ) within the oxygen concentration range (SC) at the growth temperature (GT) during the entire crystal growth step.

5. The method according to claim 1 , wherein the growth oxygen concentration value (C 2 ) decreases ( 10 ′) to a second growth oxygen concentration value (C 2 ′) within the oxygen concentration range (SC) at the growth temperature (GT) after an early stage of the crystal growth step.

6. The method according to claim 1 , wherein the growth oxygen concentration value (C 2 ) increases ( 10 ″) to a third growth oxygen concentration value (C 2 ″) within the oxygen concentration range (SC) at the growth temperature (GT) at the later stage of the crystal growth step.

7. The method according to claim 1 , wherein the growth oxygen concentration value (C 2 ) first decreases ( 10 ′) to a second growth oxygen concentration value (C 2 ′) within the oxygen concentration range (SC) at the growth temperature (GT) after an early stage of the crystal growth step, and increases ( 10 ″) to a third growth oxygen concentration value (C 2 ″) within the oxygen concentration range (SC) at the growth temperature (GT) at the later stage of the crystal growth step.

8. The method according to claim 1 , wherein the growth atmosphere ( 120 , 220 , 320 , 420 , 520 , 620 ) contains in addition to oxygen traces of H 2 and/or H 2 O to modify electrical properties of the β-Ga 2 O 3 single crystals.

9. The method according to claim 1 , wherein the growth atmosphere ( 120 ) is applied to the Czochralski method ( 100 ).

10. The method according claim 1 , wherein the growth atmosphere ( 220 ) is applied to the Kyropolous method ( 200 ).

11. The method according to claim 1 , wherein the growth atmosphere ( 320 ) is applied to the vertical Bridgman or Vertical Gradient Freeze method ( 300 ).

12. The method according to claim 1 , wherein the growth atmosphere ( 420 ) is applied to the horizontal Bridgman method ( 400 ).

13. The method according to claim 1 , wherein the growth atmosphere ( 520 ) is applied to shaped crystal growth techniques selected from the group consisting of the Stepanov, Noncapillary Shaping and Edge-Defined Film-Fed Growth methods ( 500 ).

14. The method according to claim 1 , wherein the growth atmosphere ( 620 ) is applied to the Levitation Assisted Self-Seeding Crystal Growth method ( 600 ).

15. The method according to claim 1 , wherein the growth atmosphere is applied to the Micro-Pulling Down method.

Assignees

• Forschungsverbund Berlin Ev

Inventors

• Galazka Zbigniew
• Uecker Reinhard
• Klimm Detlef
• Bickermann Matthias

Classifications

• C30B15/20 Primary

  Controlling or regulating (controlling or regulating in general G05) · CPC title

• C30B11/006

  Controlling or regulating · CPC title

• C30B15/08

  Downward pulling · CPC title

• C30B29/16 Primary

  Oxides · CPC title

• C30B11/005

  by irradiation or electric discharge · CPC title