Patterned sapphire substrate and light emitting diode
A patterned sapphire substrate has a first surface and a second surface opposite to each other; the connection zone between first protrusion portions has no C surface (i.e. (0001) surface); and the patterned sapphire substrate may have no C surface on the growth surface to reduce the threading dislocation density of the GaN epitaxial material on the sapphire substrate.
1. A patterned sapphire substrate having a first and a second opposing surfaces, wherein:
the first surface comprises a plurality of regularly-arranged first protrusion portions having a first size d1;
a connection zone between the plurality of regularly-arranged first protrusion portions has no C surface;
three adjacent first protrusion portions form a triangle, each having a second protrusion portion disposed therein with a second size d2;
d1>d2; and
the first protrusion portions and the second protrusion portions are connected directly or via curved surfaces such that the connection zone has no C surface.
2. The patterned sapphire substrate according to claim 1 , wherein the first protrusion portions have no C surfaces.
3. The patterned sapphire substrate according to claim 1 , wherein the second protrusion portions have no C surfaces.
4. The patterned sapphire substrate according to claim 1 , wherein the first surface has no C surface.
5. The patterned sapphire substrate according to claim 1 , wherein:
four adjacent first protrusion portions form a rhombus; and
between long diagonals of the rhombus are two second protrusion portions.
6. The patterned sapphire substrate according to claim 5 , wherein between short diagonals of the rhombus is a third protrusion portion with a third size d3, where d3<d2.
7. The patterned sapphire substrate according to claim 6 , wherein a recess portion is between two second protrusion portions, a lowest portion of the recess portion is a highest point of the third protrusion portion.
8. The patterned sapphire substrate according to claim 1 , wherein the second protrusion portion comprises a cone including three or more inclined surfaces, each corresponding to one of the three first protrusion portions, respectively.
9. The patterned sapphire substrate according to claim 8 , wherein an angle between the inclined surface of the second protrusion portion and the C surface of the sapphire substrate is 10°-40°.
10. The patterned sapphire substrate according to claim 8 , wherein:
between two nearest first protrusion portions, there is a V-shape notch positioned between two adjacent second protrusion portions;
two sides of the V-shape notch are formed by the inclined surfaces of two second protrusion portions.
11. The patterned sapphire substrate according to claim 1 , wherein a ratio of height h1 of the first protrusion portion and height h2 of the second protrusion portion is 2-50.
12. The patterned sapphire substrate according to claim 1 , wherein the first protrusion portion covers 50%-90% of a total area of the first surface.
13. The patterned sapphire substrate according to claim 1 , wherein: a top portion of the first protrusion portion is a cone and has a projection on the C surface as round or polygon.
14. A light emitting diode comprising:
a patterned sapphire substrate having a first and a second opposing surfaces; and
a light-emitting epitaxial laminated layer formed on the patterned sapphire substrate, wherein:
the first surface comprises a plurality of regularly-arranged first protrusion portions having a first size d1;
a connection zone between the plurality of regularly-arranged first protrusion portions has no C surface;
over the patterned sapphire substrate is an AlN layer formed via physical vapor deposition (PVD), and
the light-emitting epitaxial laminated layer is formed on the AlN layer.
15. A method of manufacturing a patterned sapphire substrate, comprising:
1) providing a sapphire substrate having of a first and a second opposing surfaces, and forming a patterned mask layer over the first surface;
2) forming a plurality of protrusion structures on the first surface via dry etching, wherein a connection zone between protrusion structures is etched to a small convex surface;
3) wet etching the first surface of the sapphire substrate to form a patterned surface having a plurality of regularly-arranged first protrusion portions with a first size d1, wherein the connection zone between first protrusion portions has no C surface;
wherein the manufactured patterned sapphire substrate has the first and second opposing surfaces, wherein:
the first surface comprises the plurality of regularly-arranged first protrusion portions having the first size d1;
the connection zone between the plurality of regularly-arranged first protrusion portions has no C surface;
the small convex surface connecting protrusion structures formed in step 2) has a height of 0.05 μm-0.5 μm;
in step 3), the patterned surface is formed by etching the first surface of the sapphire substrate with sulfur phosphoric acid mixture; and
the patterned surface formed in step 3 has a plurality of second protrusion portions in second size d2; three adjacent first protrusion portions form a triangle, each having a second protrusion portion inside, where d1>d2; and the first protrusion portion and the second protrusion portion are connected directly or via a curved surface so that the connection zone has no C surface.
16. The method of claim 15 , wherein the patterned mask layer in step 1) comprises a plurality of column light resistances, oxides, or metals.
17. The method of claim 15 , wherein the small convex surface connecting protrusion structures formed in step 2) is a curved surface.