Light emitting diode having algan buffer layer and method of fabricating the same
View Patent ↗The present invention relates to a light emitting diode having an Al x Ga 1-x N buffer layer and a method of fabricating the same, and more particularly, to a light emitting diode having an Al x Ga 1-x N buffer layer, wherein between a substrate and a GaN-based semiconductor layer, the Al x Ga 1-x N (O≦x≦1) buffer layer having the composition ratio x of Al decreasing from the substrate to the GaN-based semiconductor layer is interposed to reduce lattice mismatch between the substrate and the GaN-based semiconductor layer, and a method of fabricating the same. To this end, the present invention provides a light emitting diode comprising a substrate; a first conductive semiconductor layer positioned on the substrate; and an Al x Ga 1-x N (O≦x≦1) buffer layer interposed between the substrate and the first conductive semiconductor layer and having a composition ratio x of Al decreasing from the substrate to the first conductive semiconductor layer.
1. A light emitting diode, comprising:
a substrate;
a first conductive semiconductor layer comprising an N-type Al z In y Ga 1-z-y N (0≦z,y,z+y≦1) layer positioned on the substrate; and
an Al x Ga 1-x N (0≦x≦1) buffer layer interposed between the substrate and the first conductive semiconductor layer and comprising a first region having a composition ratio x of Al decreasing from the substrate to the first conductive semiconductor layer and a second region of the Al x Ga 1-x N buffer layer having the composition ratio of Al equal to 1,
wherein the second region contacts the first region and the substrate,
wherein the second region has a thickness of about 1 nm to about 50 nm,
wherein the first conductive semiconductor layer contacts the Al x Ga 1-x N buffer layer, and
wherein the degree of lattice mismatch between the substrate and the second region of the Al x Ga 1-x N buffer layer is smaller than the degree of lattice mismatch between the substrate and the first conductive semiconductor layer.
2. The light emitting diode as claimed in claim 1 , wherein the composition ratio of Al decreases in a linear manner.
3. The light emitting diode as claimed in claim 2 , further comprising a third region of the Al x Ga 1-x N buffer layer having the composition ratio of Al equal to 0.
4. The light emitting diode as claimed in claim 3 , wherein the third region has a thickness of about 1 nm to about 50 nm.
5. The light emitting diode as claimed in claim 3 , wherein the third region is disposed between the first conductive semiconductor layer and the first region.
6. The light emitting diode as claim in claim 3 , wherein the first conductive semiconductor layer contacts the third region.
7. The light emitting diode as claimed in claim 2 , wherein the first region has a thickness of about 1 nm to about 30 nm.
8. The light emitting diode as claim in claim 1 , wherein the second region is disposed between the substrate and the first region.
9. A method of fabricating a light emitting diode, comprising:
preparing a substrate;
forming an Al x Ga 1-x N (0≦x≦1) buffer layer directly on the substrate, the buffer layer having a composition ratio of Al decreasing away from a surface of the substrate; and
forming a GaN-based semiconductor layer comprising an N-type Al z In y Ga 1-z-y N (0≦z,y,z+y≦1) layer on the Al x Ga 1-x N buffer layer,
wherein Al x Ga 1-x N (0≦x≦1) buffer layer comprises a first region having a composition ratio x of Al decreasing from the substrate to the GaN-based semiconductor layer and a second region of the Al x Ga 1-x N buffer layer having the composition ratio of Al equal to 1,
wherein the second region contacts the first region and the substrate,
wherein the second region has a thickness of about 1 nm to about 50 nm,
wherein the GaN-based semiconductor layer contacts the Al x Ga 1-x N buffer layer, and wherein the degree of lattice mismatch between the substrate and the second region of the Al x Ga 1-x N buffer layer is smaller than the degree of lattice mismatch between the substrate and the first conductive semiconductor layer.
10. The method as claimed in claim 9 , wherein the composition of Al decreases in a linear manner.