Light emitting diode (LED) devices with nucleation layer
Described are light emitting diode (LED) devices having patterned substrates and methods for effectively growing epitaxial III-nitride layers on them. A nucleation layer, comprising a III-nitride material, is grown on a substrate before any patterning takes place. The nucleation layer results in growth of smooth coalesced III-nitride layers over the patterns.
1. A light emitting diode device comprising:
a nucleation layer on a substrate, the nucleation layer comprising a first III-nitride material, the nucleation layer having a thickness in a range of from about 5 nm to about 100 nm;
a patterned dielectric layer on a top surface of the nucleation layer, the patterned dielectric layer comprising a plurality of features and having a plurality of spaces between the plurality of features, the plurality of features having a top surface and sidewalls and a height in a range of from 100 nm to 3 μm, a pitch in a range of from 50 nm to 5000 nm, and a width in a range of from 5 nm to 500 nm, the sidewalls having a bottom portion and an upper portion, the plurality of features protruding from a top surface of the nucleation layer and the plurality of spaces exposing a top surface of the nucleation layer, the plurality of features having a shape selected from a hemispherical shape, a triangular pyramidal shape, a quadrangular pyramidal shape, a hexagonal pyramidal shape, a conical shape, a semi-spherical shape, or a cut-spherical shape; and
a III-nitride layer on the plurality of features and on the plurality of spaces, the III-nitride layer comprising a second III-nitride material, wherein the III-nitride layer is on the bottom portion of the sidewalls of the plurality of features and on the plurality of spaces, and wherein the III-nitride layer is not on the upper portion of the sidewalls of the plurality of features.
2. The light emitting diode device of claim 1 , wherein the first III-nitride material and the second III-nitride material independently comprise one or more of aluminum, gallium, and indium.
3. The light emitting diode device of claim 2 , wherein the first III-nitride material comprises aluminum nitride (AlN).
4. The light emitting diode device of claim 2 , wherein the first III-nitride material and the second III-nitride material are the same.
5. The light emitting diode device of claim 1 , wherein the dielectric layer comprises a low refractive index material having a refractive index in a range of from about 1.2 to about 2.
6. The light emitting diode device of claim 5 , wherein the dielectric layer comprises one or more of silicon oxide (SiO 2 ) and silicon nitride (Si 3 N 4 ).
7. The light emitting diode device of claim 1 , wherein the second III-nitride material comprises gallium nitride (GaN).
8. The light emitting diode device of claim 1 , wherein the nucleation layer has a thickness in a range of from 5 nm to 50 nm.
9. A method of manufacturing, comprising:
depositing a nucleation layer on a substrate, the nucleation layer comprising a first III-nitride material, the nucleation layer having a thickness in a range of from about 5 nm to about 100 nm;
depositing a dielectric layer on a top surface of the nucleation layer, the dielectric layer comprising a low refractive index dielectric material;
patterning the dielectric layer to form a patterned surface having a plurality of features and a plurality of spaces between the plurality of features, the plurality of features having a top surface and sidewalls and a height in a range of from 100 nm to 3 μm, a pitch in a range of from 50 nm to 5000 nm, and a width in a range of from 5 nm to 500 nm, the sidewalls having a bottom portion and an upper portion; and
epitaxially growing a III-nitride layer on the patterned surface, the III-nitride layer comprising a second III-nitride material, wherein the III-nitride layer is grown on the bottom portion of the sidewalls of the plurality of features and on the plurality of spaces, and wherein the III-nitride layer is not grown on the upper portion of the sidewalls of the plurality of features.
10. The method of claim 9 , wherein the plurality of features protrude from a top surface of the nucleation layer and have a height and a width and sidewalls, and the plurality of spaces expose the top surface of the nucleation layer, and the plurality of features having a shape selected from a hemispherical shape, a triangular pyramidal shape, a quadrangular pyramidal shape, a hexagonal pyramidal shape, a conical shape, a semi-spherical shape, or a cut-spherical shape.
11. The method of claim 10 , wherein the III-nitride layer grows on the exposed top surface of the nucleation layer and does not grow on the sidewalls of the plurality of features.
12. The method of claim 9 , wherein the nucleation layer is deposited by one or more of sputter deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced atomic layer deposition (PEALD), and plasma enhanced chemical vapor deposition (PECVD).
13. The method of claim 9 , wherein the nucleation layer has a thickness in a range of from 5 nm to 50 nm.