Method of fabricating optical devices using laser treatment of contact regions of gallium and nitrogen containing material
View Patent ↗A method for forming optical devices includes providing a gallium nitride substrate having a crystalline surface region and a backside region. The backside is subjected to a laser scribing process to form scribe regions. Metal contacts overly the scribe regions.
1. An optical device comprising:
a gallium and nitrogen containing substrate having a crystalline surface region and a backside opposite the crystalline surface region;
at least one ablated region characterized by a v-shaped profile or a trench-shaped profile on the backside of the gallium and nitrogen containing substrate, where sides and a bottom of the at least one ablated region are gallium rich and have a higher gallium concentration than a surface of the backside of the gallium and nitrogen containing substrate that is laterally spaced from the at least one ablated region; and
a metal contact contacting the backside of the gallium and nitrogen containing substrate and covering at least a portion of the at least one ablated region to form a contact region.
2. The device of claim 1 further comprising a laser stripe region overlying at least a portion of the crystalline surface region.
3. The device of claim 2 , wherein the at least one ablated region is aligned with the laser stripe region.
4. The device of claim 1 wherein the metal contact is an n-type metal contact.
5. The device of claim 1 further comprising an n-type gallium nitride region overlying the crystalline surface region, an active region overlying the n-type gallium nitride region, and a laser stripe region overlying the active region.
6. The device of claim 5 wherein the active region includes one to twenty quantum well regions, the active region characterized by a thickness of 10 Angstroms to about 100 Angstroms.
7. The device of claim 1 wherein the at least one ablated region corresponds to the contact region.
8. The device of claim 1 , wherein the at least one ablated region is characterized by a depth from 15 μm to 20 μm and a width from 0.5 μm to 50μm.
9. The device of claim 1 , wherein the at least one ablated region comprises an elemental gallium region.
10. The device of claim 1 , wherein the at least one ablated region is formed using a laser.
11. The device of claim 10 , wherein the laser is a UV laser.
12. The device of claim 11 , wherein the laser is characterized by a power of 30 mW to 300 mW.
13. The device of claim 11 , wherein the laser is characterized by a power from 10 mW to 50 mW.
14. The device of claim 1 , comprising a laser ridge, wherein the at least one ablated region is parallel to the laser ridge.
15. The device of claim 1 , wherein the at least one ablated region is characterized by a depth from 3 μm to 60 μm.
16. The device of claim 1 , wherein the at least one ablated region comprises a plurality of parallel ablated regions.
17. The device of claim 1 , wherein the metal contact overlies the at least one ablated region.
18. The device of claim 1 , wherein the at least one ablated region penetrates into a portion of the gallium and nitrogen containing substrate.
19. The device of claim 1 , wherein the metal contact comprises a material selected from aluminum, nickel, gold, titanium, platinum, silicon, and a combination of any of the foregoing.
20. The device of claim 1 , wherein the at least one ablated region is characterized by a length from 50 μm to 3,000 μm.
21. The device of claim 1 , wherein the metal contact is ohmic.