Light emitting device having micro epitaxial structures and manufacturing method thereof
A light emitting device includes a first substrate, a second substrate and a plurality of micro epitaxial structures. The second substrate is disposed opposite to the first substrate. The micro epitaxial structures are periodically disposed on the substrate and located between the first substrate and the second substrate. A coefficient of thermal expansion of the first substrate is CTE1, a coefficient of thermal expansion of the second substrate is CTE2, a side length of each of the micro epitaxial structures is W, W is in the range between 1 micrometer and 100 micrometers, and a pitch of any two adjacent micro epitaxial structures is P, wherein W/P=0.1 to 0.95, and CTE2/CTE1=0.8 to 1.2.
1. A light emitting device, comprising:
a first substrate;
a second substrate, disposed opposite to the first substrate; and a plurality of micro epitaxial structures, periodically disposed on the first substrate and bonded with the second substrate via a thermocompression bonding method, wherein a coefficient of thermal expansion of the first substrate is CTE1, a coefficient of thermal expansion of the second substrate is CTE2, a side length of each of the micro epitaxial structures is W, W ranges from 1 to 100 micrometers, and a pitch of any two adjacent micro epitaxial structures is P, wherein W/P=0.1 to 0.95, and CTE2/CTE1=0.8 to 1.2;
a first bonding layer, disposed between the micro epitaxial structures and the second substrate, and the second substrate is fixed on the first substrate through the first bonding layer;
a second bonding layer, disposed between the micro epitaxial structures and the first substrate, and the micro epitaxial structures are fixed on the first substrate through the second bonding layer; and
wherein a side of each of the micro epitaxial structures directly contacts the first bonding layer, and the second bonding layer encapsulates each of the micro epitaxial structures.
2. The light emitting device as recited in claim 1 , wherein when W/P ranges from 0.1 to 0.6, CTE2/CTE1=0.9 to 1.1.
3. The light emitting device as recited in claim 1 , wherein the first substrate and the second substrate have approximately the same size and shape.
4. The light emitting device as recited in claim 1 , wherein the first bonding layer fills up gaps between the micro epitaxial structures.
5. The light emitting device as recited in claim 1 , further comprising:
an insulating material, filling up gaps between the micro epitaxial structures.
6. The light emitting device as recited in claim 1 , wherein the second bonding layer fills up gaps between micro epitaxial structures.
7. The light emitting device as recited in claim 1 , wherein a current density at the highest peak value of an external quantum efficiency curve of each of the micro epitaxial structures is below 2 A/cm 2 .
8. The light emitting device as recited in claim 1 , wherein a defect density of each of the micro epitaxial structures is less than 10 8 /cm 2 .
9. A manufacturing method of a light emitting device, comprising:
providing a first substrate, a coefficient of thermal expansion of the first substrate being CTE1, and the first substrate having a plurality of micro epitaxial structures periodically fixed on the first substrate through an adhesive layer, wherein the adhesive layer fills up gaps between micro epitaxial structures, wherein a side length of each of the micro epitaxial structures is W, W ranges from 1 to 100 micrometers, a pitch of any two adjacent micro epitaxial structures is P, and W/P=0.1 to 0.95;
providing a bonding material covered on the micro epitaxial structures via a film coating method on the first substrate;
disposing a second substrate opposite to the first substrate, the micro epitaxial structures being located between the first substrate and the second substrate, and the second substrate being bonded with the micro epitaxial structures through the bonding material via a thermocompression bonding method, wherein a coefficient of thermal expansion of the second substrate is CTE2, and CTE2/CTE1=0.8 to 1.2; and
separating the first substrate from the micro epitaxial structures.
10. The manufacturing method of the light emitting device as recited in claim 9 , wherein when W/P ranges from 0.1 to 0.6, CTE2/CTE1=0.9 to 1.1.
11. The manufacturing method of the light emitting device as recited in claim 9 , wherein the bonding material, after being covered on the micro epitaxial structures via a spin coating method, is bonded with the second substrate.
12. The manufacturing method of the light emitting device as recited in claim 11 , wherein the spin coating method is multiple times of spin coating.
13. The manufacturing method of the light emitting device as recited in claim 11 , wherein the bonding material fills up gaps between micro epitaxial structures.