Laser diode orientation on mis-cut substrates
View Patent ↗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.
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 2 0> 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 1 00> direction; and
(b) a laser facet oriented on a cleavage plane orthogonal to the <1 1 00> direction.
2. The electronic device of claim 1 , 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.
3. The electronic device of claim 1 , 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.
4. The electronic device of claim 1 , 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.
5. The electronic device of claim 1 , comprising a laser diode cavity on the substrate oriented parallel to the <1 1 00> direction.
6. The electronic device of claim 1 , comprising a laser facet oriented on a cleavage plane orthogonal to the <1 1 00> direction.
7. The electronic device of claim 1 , comprising a facet oriented on a cleavage plane orthogonal to the <1 1 00> 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 2 0> 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 1 00> direction, wherein the offcut surface provides lattice steps parallel to the <11 2 0> 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 1 00> 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 1 00> 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 2 0> direction has a tilt direction that is oriented to within ±15 degrees of the <11 2 0> 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 2 0> direction and further comprising a substrate flat that defines a cleavage plane orthogonal to the <1 1 00> 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 2 0> 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.