Vertical light emitting diode and method of making a vertical light emitting diode
View Patent ↗A vertical gallium-nitrate-based LED and method of making a vertical gallium-nitrate-based LED using a stop layer is provided. Embodiments of the present invention use mechanical thinning and a plurality of superhard stop points to remove epitaxial layers with a high level of certainty. According one embodiment, the method of making a vertical LED includes forming a plurality of layers on a sapphire substrate, forming a plurality of stop points in the plurality of layers, removing the sapphire substrate and part of a u-GaN layer using mechanical thinning, wherein the mechanical thinning stops at an end of the plurality of stop points, selectively etching the u-GaN layer and exposing at least a part of the highly doped stop layer, and forming an n-electrode on the highly doped stop layer.
1. A method of making a vertical GaN-based LED, the method comprising:
providing a sapphire substrate;
sequentially forming a u-GaN layer, a highly doped stop layer, an n-type GaN layer, an active layer, and a p-type GaN layer on the sapphire substrate, wherein the u-GaN layer, a highly doped stop layer, an n-type GaN layer, an active layer, and a p-type GaN layer are a plurality of layers;
forming a plurality of stop points in the plurality of layers;
forming a conductive substrate on the p-type GaN layer;
removing the sapphire substrate using mechanical thinning;
removing a part of the u-GaN layer using mechanical thinning, wherein the mechanical thinning stops at an end of the plurality of stop points;
selectively etching the u-type GaN layer and exposing at least a part of the highly doped stop layer;
removing the u-type GaN layer; and
forming an n-electrode on the highly doped stop layer.
2. The method of claim 1 , wherein the step of selectively etching the u-GaN layer is high selective photoelectrochemical (PEC) etching.
3. The method of claim 1 , wherein the hardness of the plurality of stop points is greater than the hardness of the sapphire substrate.
4. The method of claim 1 , wherein the highly doped stop layer is one or more layers of AlInGaN.
5. The vertical GaN-based LED of claim 4 , wherein the composition of the AlInGaN is Al x In y Ga (1-x-y) N.
6. The vertical GaN-based LED of claim 5 , wherein x is less than or equal to approximately 0.35 and y is less than or equal to approximately 0.1.
7. The vertical GaN-based LED of claim 1 , wherein the highly doped stop layer is one or more layers of AlGaN.
8. The vertical GaN-based LED of claim 7 , wherein the composition of AlGaN is Al x Ga (1-x) N.
9. The vertical GaN-based LED of claim 8 , wherein x is less than or equal to approximately 0.35.
10. The vertical GaN-based LED of claim 1 , wherein the highly doped stop layer is a AlN/GaN super lattice structure.
11. The vertical GaN-based LED of claim 10 , wherein the AlN/GaN super lattice structure includes two or more pairs of AlN and GaN layers.