Laser diode orientation on mis-cut substrates

• US 7,884,447 B2
• Filed: 06/27/2006
• Issued: 02/08/2011
• Est. Priority Date: 07/11/2005
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Brandes, George R., Xu, Xueping, Vaudo, Robert P.
• Primary Examiner(s): HO, TU TU V
• Application Number:
  US11/994,406
• Publication Number:
  US 20080265379A1
• Time in Patent Office: 1,687 Days
• Field of Search: 257/627, 257/628, 257/E31.04, 438/973, 372/44.011, 372/45.01
• US Class Current: 257/627
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP
• CPC Class Codes: Y10S 438/973 Substrate orientation

Abstract

A microelectronic assembly in which a semiconductor device structure is directionally positioned on an off-axis substrate (201). In an illustrative implementation, a laser diode is oriented on a GaN substrate (201) wherein the GaN substrate includes a GaN (0001) surface off-cut from the <0001> direction predominantly towards either the <1120> or the <1100> family of directions. For a <1120> off-cut substrate, a laser diode cavity (207) may be oriented along the <1100> direction parallel to lattice surface steps (202) of the substrate (201) in order to have a cleaved laser facet that is orthogonal to the surface lattice steps. For <1100> off-cut substrate, the laser diode cavity may be oriented along the <1100> direction orthogonal to lattice surface steps (207) of the substrate (201) in order to provide a cleave laser facet that is aligned with the surface lattice steps.

Claims

1. An electronic device comprising a III-V nitride substrate having a III-V nitride (0001) surface off-cut from the <

0001>

direction predominantly towards the <

11 20>

direction, and comprising at least one of the following features (a) and (b);

(a) a laser diode cavity on the substrate oriented parallel to the <

1 100>

direction; and

(b) a laser facet oriented on a cleavage plane orthogonal to the <

1 100>

direction.

2. The electronic device of claim 1, wherein the surface off-cut from the <

0001>

direction predominantly towards the <

11 20>

direction has an off-cut surface angle in a range of from about 0.2 to about 10 degrees.

3. The electronic device of claim 1, wherein the surface off-cut from the <

0001>

direction predominantly towards the <

11 20>

direction has a tilt direction that is oriented to within ±

15 degrees of the <

11 20>

direction.

4. The electronic device of claim 1, wherein the surface off-cut from the <

0001>

direction predominantly towards the <

11 20>

direction has a tilt direction that is oriented to within ±

5 degrees of the <

11 20>

direction.

5. The electronic device of claim 1, comprising a laser diode cavity on the substrate oriented parallel to the <

1 100>

direction.

6. The electronic device of claim 1, comprising a laser facet oriented on a cleavage plane orthogonal to the <

1 100>

direction.

7. The electronic device of claim 1, comprising a facet oriented on a cleavage plane orthogonal to the <

1 100>

direction, wherein the substrate comprises a substrate flat having a flat tolerance of less than 5 degrees of azimuthal orientation.

8. The electronic device of claim 7, wherein the substrate comprises a substrate flat having a flat tolerance of less than 1 degree of azimuthal orientation.

9. The electronic device of claim 1, including a substrate flat that is positioned to define the <

11 20>

direction of the cleavage plane.

10. The electronic device of claim 5, comprising a doped epitaxial film on the laser diode cavity.

11. The electronic device of claim 1, comprising epitaxial layers grown on said substrate.

12. The electronic device of claim 1, comprising a laser diode.

13. The electronic device of claim 1, wherein the III-V nitride substrate is a GaN substrate.

14. The electronic device of claim 1, further comprising top contacts.

15. The electronic device of claim 1, comprising a vertical device.

16. An electronic device comprising a III-V nitride substrate, wherein the III-V nitride substrate includes a III-V nitride (0001) surface off-cut from the <

0001>

direction predominantly towards the <

1 100>

direction, wherein the offcut surface provides lattice steps parallel to the <

11 20>

direction, and the device comprises a laser diode cavity formed on the off-cut substrate surface such that the cavity direction is oriented along the <

1 100>

direction orthogonal to lattice surface steps of the substrate.

17. The electronic device of claim 16, wherein the off-cut surface is characterized by an off-cut angle in a range of from 0.2 to 10 degrees.

18. The electronic device of claim 16, including a cleavage plane that is orthogonal to the <

1 100>

direction yielding a cleaved facet that contains the c-axis vector.

19. The electronic device of claim 16, comprising a laser diode.

20. The electronic device of claim 16, wherein the surface off-cut from the <

0001>

direction predominantly towards the <

11 20>

direction has a tilt direction that is oriented to within ±

15 degrees of the <

11 20>

direction.

21. The electronic device of claim 16, comprising a doped epitaxial film on or over the laser diode cavity.

22. The electronic device of claim 16, comprising epitaxial layers grown on said substrate.

23. A III-V nitride substrate including a III-V nitride (0001) surface off-cut from the <

0001>

direction predominantly towards the <

11 20>

direction and further comprising a substrate flat that defines a cleavage plane orthogonal to the <

1 100>

direction, wherein the substrate flat has a flat tolerance of less than 5 degrees of azimuthal orientation.

24. The III-V nitride substrate of claim 23, wherein the surface off-cut from the <

0001>

direction predominantly towards the <

11 20>

direction has an off-cut angle in a range of from 0.2 to 10 degrees.

25. The III-V nitride substrate of claim 23, comprising at least one facet and comprising a laser diode cavity arranged substantially orthogonal to the at least one facet.

26. The III-V nitride substrate of claim 23, wherein the substrate is cleaved along the cleavage plane.

27. An electronic device comprising the III-V nitride substrate of claim 23.

28. The electronic device of claim 27, comprising any of an optoelectronic device, a microelectronic device, and a semiconductor device.

29. The electronic device of claim 27, comprising a laser diode.