Indium gallium nitride-based Ohmic contact layers for gallium nitride-based devices
View Patent ↗Light emitting devices include a gallium nitride-based epitaxial structure that includes an active light emitting region and a gallium nitride-based outer layer, for example gallium nitride. A indium nitride-based layer, such as indium gallium nitride, is provided directly on the outer layer. A reflective metal layer or a transparent conductive oxide layer is provided directly on the indium gallium nitride layer opposite the outer layer. The indium gallium nitride layer forms a direct ohmic contact with the outer layer. An ohmic metal layer need not be used. Related fabrication methods are also disclosed.
1. A light emitting device comprising:
a gallium nitride-based epitaxial structure that includes an active light emitting region and a gallium nitride-based outer layer;
an undoped indium gallium nitride-based layer directly on the gallium nitride-based outer layer;
an ohmic metal layer directly on the undoped indium gallium nitride-based layer opposite the gallium nitride-based outer layer; and
a reflective metal layer directly on the ohmic metal layer opposite the undoped indium gallium nitride-based layer.
2. A light emitting device according to claim 1 wherein the gallium nitride-based layer is doped P-type.
3. A light emitting device according to claim 1 wherein the reflective metal layer comprises silver, nickel-silver alloy and/or aluminum.
4. A light emitting device according to claim 1 wherein the ohmic metal layer comprises nickel.
5. A light emitting device according to claim 1 wherein the undoped indium gallium nitride-based layer is between about 5 Å and about 100 Å thick.
6. A light emitting device according to claim 1 wherein the gallium nitride-based outer layer includes a nonplanar outer surface and wherein the undoped indium gallium nitride-based layer is also nonplanar.
7. A light emitting device according to claim 1 further comprising a barrier layer on the reflective metal layer opposite the undoped indium gallium nitride-based layer and a bonding layer on the barrier layer opposite the reflective metal layer.
8. A light emitting device according to claim 1 further comprising a substrate on the gallium nitride-based epitaxial structure opposite the outer layer.
9. A semiconductor device comprising:
a gallium nitride-based epitaxial structure that includes a gallium nitride-based outer layer;
a binary indium nitride layer directly on the gallium nitride-based outer layer; and
a substrate on the gallium nitride-based epitaxial structure opposite the outer layer.
10. A device according to claim 9 wherein the gallium nitride-based outer layer is doped P-type.
11. A semiconductor device comprising:
a gallium nitride-based epitaxial structure that includes a gallium nitride-based outer layer; and
a binary indium nitride layer directly on the gallium nitride-based outer layer,
wherein the gallium nitride-based epitaxial structure includes an active High Electron Mobility Transistor (HEMT) region.
12. A semiconductor device comprising:
a gallium nitride-based epitaxial structure; and
an indium gallium nitride-based layer including therein clusters of elemental indium and/or binary indium nitride, on the gallium nitride-based epitaxial structure.
13. A light emitting device according to claim 12 wherein the indium gallium nitride-based layer including therein clusters of elemental indium and/or binary indium nitride is directly on the gallium nitride-based epitaxial structure.
14. A light emitting device according to claim 12 wherein indium gallium nitride-based layer including therein clusters of elemental indium and/or binary indium nitride is a ternary indium gallium nitride layer including therein clusters of elemental indium and/or binary indium nitride.
15. A light emitting device according to claim 12 further comprising a substrate on the gallium nitride-based epitaxial structure opposite the indium gallium nitride-based layer.
16. A device according to claim 12 wherein the gallium nitride-based epitaxial structure includes an active High Electron Mobility Transistor (HEMT) region.