Orientation of electronic devices on mis-cut substrates
View Patent ↗A microelectronic assembly in which a semiconductor device structure is directionally positioned on an off-axis substrate. In an illustrative implementation, a laser diode is oriented on a GaN substrate wherein the GaN substrate includes a GaN (0001) surface off-cut from the <0001>direction predominantly towards either the <11 2 0> or the <1 1 00> family of directions. For a <11 2 0> off-cut substrate, a laser diode cavity may be oriented along the <1 1 00> direction parallel to lattice surface steps of the substrate in order to have a cleaved laser facet that is orthogonal to the surface lattice steps. For a <1 1 00> off-cut substrate, the laser diode cavity may be oriented along the <1 1 00> direction orthogonal to lattice surface steps of the substrate in order to provide a cleaved laser facet that is aligned with the surface lattice steps.
1. A III-V nitride substrate having an (Al,Ga,In)N off-cut surface with a plurality of parallel steps, each step of the plurality of parallel steps having a first step face and a second step face meeting along a crest, wherein each first step face and each second step face is orthogonal to a cleavage plane, and wherein the off-cut surface is off-cut from a <0001>direction and has a tilt direction oriented to within ±15 degrees of the <11 2 0> direction.
2. The III-V nitride substrate of claim 1 , wherein the <11 2 0>direction includes the [11 2 0] direction.
3. The III-V nitride substrate of claim 1 , wherein the off-cut surface has an off-cut angle in a range of from 0.2 to 10 degrees.
4. The III-V nitride substrate of claim 1 , wherein the substrate is cleaved along the cleavage plane.
5. The III-V nitride substrate of claim 1 , comprising a substrate flat disposed substantially parallel to the cleavage plane.
6. The III-V nitride substrate of claim 1 , comprising a substrate flat having a flat tolerance of less than 5 degrees of azimuthal orientation.
7. The III-V nitride substrate of claim 1 , comprising a facet oriented on the cleavage plane.
8. The III-V nitride substrate of claim 1 , wherein the III-V nitride substrate is a GaN substrate.
9. The III-V nitride substrate of claim 1 , comprising a laser diode cavity disposed parallel to each first step face and each second step face.
10. The III-V nitride substrate of claim 9 , further comprising at least one facet, wherein the laser diode cavity is substantially orthogonal to the at least one facet.
11. An electronic device comprising the III-V nitride substrate of claim 1 , comprising any of an optoelectronic device, a microelectronic device, and a semiconductor device.
12. The electronic device of claim 11 , further comprising epitaxial layers grown on or over at least a portion of the III-V nitride substrate.
13. The electronic device of claim 11 , comprising a vertical device.
14. A III-V nitride substrate including a III-V nitride (0001) surface off-cut from a <0001> direction predominantly towards a <11 2 0> direction and including a substrate flat, wherein the substrate flat has a flat tolerance of less than 5 degrees of azimuthal orientation.
15. The III-V nitride substrate of claim 14 , wherein the <11 2 0> direction includes the [11 2 0] direction.
16. The III-V nitride substrate of claim 14 , wherein the substrate flat has a flat tolerance of less than 1 degree of azimuthal orientation.
17. The III-V nitride substrate of claim 14 , wherein the substrate flat defines a cleavage plane.
18. The III-V nitride substrate of claim 14 , wherein the surface off-cut from the <0001> direction predominantly towards the <11 2 0> direction has an off-cut surface angle in a range of from about 0.2 to about 10 degrees.
19. The III-V nitride substrate of claim 14 , wherein the surface off-cut from the <0001> direction predominantly towards the <11 2 0> direction has a tilt direction that is oriented to within ±15 degrees of the <11 2 0> direction.
20. The III-V nitride substrate of claim 14 , wherein the surface off-cut from the <0001> direction predominantly towards the <11 2 0> direction has a tilt direction that is oriented to within ±5 degrees of the <11 2 0> direction.
21. The III-V nitride substrate of claim 14 , wherein the III-V nitride substrate is a GaN substrate.
22. An electronic device comprising the III-V nitride substrate of claim 14 , comprising any of an optoelectronic device, a microelectronic device, and a semiconductor device.
23. The electronic device of claim 22 , further comprising epitaxial layers grown on or over at least a portion of the III-V nitride substrate.
24. The electronic device of claim 22 , wherein the substrate flat is disposed substantially parallel to a cleavage plane of the substrate.
25. The electronic device of claim 22 , wherein the substrate is cleaved along the cleavage plane.
26. The electronic device of claim 22 , comprising a vertical device.
27. The electronic device of claim 22 , comprising a facet oriented on the cleavage plane.
28. The electronic device of claim 22 , comprising a laser diode cavity on the substrate oriented parallel to the <1 1 00> direction.
29. A III-V nitride substrate having an (Al,Ga,In)N off-cut surface with a plurality of parallel steps, each step of the plurality of parallel steps having a first step face and a second step face meeting along a crest, wherein each first step face and each second step face is orthogonal to a cleavage plane, and wherein parallel steps of the plurality of parallel steps are disposed parallel to a <11 2 0> direction.