Light emitting devices with self aligned ohmic contacts
View Patent ↗Methods of fabricating light emitting diodes and light emitting devices are provided that include a substrate, an n-type epitaxial region on the substrate and a p-type epitaxial region on the n-type epitaxial region. At least a portion of the p-type epitaxial region comprises a mesa with respect to the substrate. An ohmic contact is provided on an exposed portion of the p-type epitaxial layer. The ohmic contact is self aligned to a sidewall of the mesa and to the p-type epitaxial layer such that a sidewall of the ohmic contact is substantially aligned with a sidewall of the mesa and to the p-type epitaxial layer.
1. A light emitting device, comprising:
a substrate;
an n-type epitaxial region on the substrate;
a p-type epitaxial region on the n-type epitaxial region, at least a portion of the p-type epitaxial region comprising a mesa with respect to the substrate, wherein the mesa has opposing sidewalls extending completely through the p-type epitaxial region, and wherein portions of the p-type epitaxial region adjacent the opposing sidewalls of the mesa have an increased resistance relative to other portions thereof;
an ohmic contact on an exposed portion of the p-type epitaxial region, wherein opposing sidewalls of the ohmic contact are substantially aligned with the opposing sidewalls of the mesa and to the p-type epitaxial region.
2. The light emitting device of claim 1 , wherein a sidewall of the mesa is configured such that a portion of the substrate extends beyond the sidewall of the mesa.
3. The light emitting device of claim 1 , wherein the opposing sidewalls of the mesa extend completely through the n-type epitaxial region, and wherein portions of the n-type epitaxial region of the mesa adjacent the opposing sidewalls of the mesa have an increased resistance relative to other portions thereof.
4. The light emitting device of claim 3 , wherein the mesa has a sidewall extending to the substrate.
5. The light emitting device of claim 1 , wherein the light emitting device comprises a light emitting diode.
6. The light emitting device of claim 1 , wherein the light emitting device comprises a laser diode.
7. The light emitting device of claim 1 , wherein the p-type epitaxial region comprises a Group III-nitride epitaxial layer and the n-type epitaxial region comprises a Group III-nitride epitaxial layer.
8. The light emitting device of claim 7 , wherein the substrate comprises a SiC substrate.
9. The light emitting device of claim 7 , wherein the substrate comprises a sapphire substrate.
10. The light emitting device of claim 7 , wherein the ohmic contact comprises platinum.
11. The light emitting device of claim 1 , further comprising:
a mask on the ohmic contact opposite the p-type epitaxial region, wherein opposing sidewalls of the mask are substantially aligned with opposing sidewalls of the ohmic contact and with the opposing sidewalls of the mesa.