Control of basal plane dislocations in large aluminum nitride crystals
OwnerRobert T. BONDOKOV, Sean P. BRANAGAN +4inventors
InventorsRobert T. BONDOKOV, Sean P. BRANAGAN, James GRANDUSKY, Kasey HOGAN, Justin MARK, Jianfeng CHEN
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Abstract
In various embodiments, aluminum nitride single crystals are rapidly diameter-expanded during growth and have large crystal augmentation parameters. The aluminum nitride single crystals advantageously have low densities of basal plane dislocations and large substrate versatility metrics.
Claims68
An AlN single crystal having a diameter that increases, along at least a portion of a length of the AlN single crystal, from a minimum diameter to a maximum diameter, the AlN single crystal having a crystal augmentation parameter (CAP), in mm, greater than 20 and less than 44, the CAP being defined by:
- CAP
- =
- A
- E
- -
- A
- S
- L
- E
- =
- π
- 4
- ×
- L
- E
-
- (
- d
- E
- 2
- -
- d
- S
- 2
- )
- wherein AE, in mm2, is the cross-sectional area of the AlN single crystal at the maximum diameter, dE is the maximum diameter of the AlN single crystal in mm, AS, in mm2, is the cross-sectional area of the AlN single crystal at the minimum diameter, dS is the minimum diameter in mm, and LE is an expansion length, in mm, of the at least a portion of the AlN single crystal along which the diameter increases from the minimum diameter to the maximum diameter, and
- wherein:
- the LE of the AlN single crystal is at least 14 mm, and/or
- (i) the AlN single crystal has an expanded portion having the maximum diameter, (ii) a length of the expanded portion is greater than LE, and (iii) a sum of the length of the expanded portion and LE is at least 14 mm.
An AlN single-crystal substrate having a diameter of at least 2.5 cm and having a substrate versatility (SuV) metric, in cm2, greater than 3, the SuV metric being defined by:
- SuV
- =
- A
- [
- log
-
- (
- BPD
- +
- 0.1
- )
- +
- 1
- .
- 1
- ]
- ×
- 1
-
- 0
- t
- ≅
- 0
- .
- 7
-
- 8
-
- 5
-
- d
- 2
- [
- log
-
- (
- BPD
- +
- 0.1
- )
- +
- 1
- .
- 1
- ]
- ×
- 1
-
- 0
- t
- wherein A is the substrate area in cm2, d is the substrate diameter in cm, t is the substrate thickness in cm, and BPD is the basal plane dislocation density, in cm−2, in a center region of the substrate having an area greater than 1 mm2.
An AlN single-crystal substrate having a diameter of at least 2.5 cm and having a basal plane dislocation density of less than 1 cm−2 in a center region of the substrate having an area greater than 1 mm2.
Dependencies are inferred from the claim text.