Nitride semiconductor light-emitting device including a buffer layer on a substrate and method for manufacturing the same
There are provided a nitride semiconductor light-emitting device and a method for manufacturing the same. The nitride semiconductor light-emitting device includes a buffer layer on a sapphire substrate, wherein the buffer layer includes a plurality of layers having different lattice constants, a first n-type nitride semiconductor layer on the buffer layer, an active layer on the first n-type nitride semiconductor layer, and a p-type nitride semiconductor layer on the active layer.
1. A nitride semiconductor light-emitting device comprising:
a buffer layer on a substrate, wherein the buffer layer includes a plurality of layers having different lattice constants;
a first n-type nitride semiconductor layer on the buffer layer;
an active layer on the first n-type nitride semiconductor layer;
a p-type nitride semiconductor layer on the active layer,
wherein the buffer layer comprises:
a first buffer layer on the substrate, wherein the first buffer layer has a larger lattice constant than the substrate;
a second buffer layer on the first buffer layer, wherein the second buffer layer has a smaller lattice constant than the first buffer layer; and
a third buffer layer on the second buffer layer, wherein the third buffer layer has a smaller lattice constant than the second buffer layer,
wherein a difference of lattice constant between the third buffer layer and the first n-type nitride semiconductor layer is smaller than a difference of lattice constant between the second buffer layer and the n-type nitride semiconductor layer, and
wherein the third buffer layer includes AIN, and
wherein the substrate includes a sapphire substrate.
2. The nitride semiconductor light-emitting device according to claim 1 , comprising a second n-type nitride semiconductor layer on the p-type nitride semiconductor layer.
3. The nitride semiconductor light-emitting device according to claim 1 , wherein the first n-type nitride semiconductor layer includes GaN layer, and
the second buffer layer includes III-V group elements having lattice constant which is larger than the first n-type nitride semiconductor layer thereof and smaller than the first buffer layer thereof.
4. The nitride semiconductor light-emitting device according to claim 1 , wherein the first buffer layer includes at least one selected from the group consisting of III-V, II-VI and IV-IV group elements.
5. The nitride semiconductor light-emitting device according to claim 1 , further comprising a p-electrode on the p-type nitride semiconductor layer, the p-electrode comprises a transparent electrode formed of one selected from the group consisting of ITO, ZnO, RuOx, TiOx, and IrOx.
6. A nitride semiconductor light-emitting device comprising:
a buffer layer on a substrate, wherein the buffer layer includes a plurality of layers having different lattice constants;
a first n-type nitride semiconductor layer on the buffer layer;
an active layer on the first n-type nitride semiconductor layer;
a p-type nitride semiconductor layer on the active layer,
wherein the buffer layer comprises:
a first buffer layer on the substrate, wherein the first buffer layer has a larger lattice constant than the substrate;
a second buffer layer on the first buffer layer, wherein the second buffer layer has a smaller lattice constant than the first buffer layer; and
a third buffer layer on the second buffer layer, wherein the third buffer layer has a smaller lattice constant than the second buffer layer,
wherein a difference of lattice constant between the third buffer layer and the first n-type nitride semiconductor layer is smaller than a difference of lattice constant between the second buffer layer and the n-type nitride semiconductor layer, and
wherein the third buffer layer includes AIN; and
an undoped nitride semiconductor layer between the buffer layer and the first n-type nitride semiconductor layer.
7. The nitride semiconductor light-emitting device according to claim 6 , wherein a difference of lattice constant between the third buffer layer and the undoped nitride semiconductor layer is smaller than a difference of lattice constant between the second buffer layer and the undoped nitride semiconductor layer.
8. A nitride semiconductor light-emitting device comprising:
a buffer layer on a substrate, wherein the buffer layer includes a plurality of layers having different lattice constants;
a first n-type nitride semiconductor layer on the buffer layer;
an active layer on the first n-type nitride semiconductor layer; and
a p-type nitride semiconductor layer on the active layer,
wherein the buffer layer comprises:
a first buffer layer on the substrate, wherein the first buffer layer has a larger lattice constant than the substrate;
a second buffer layer on the first buffer layer, wherein the second buffer layer has a smaller lattice constant than the first buffer layer; and
a third buffer layer on the second buffer layer, wherein the third buffer layer has a smaller lattice constant than the second buffer layer,
wherein a difference of lattice constant between the third buffer layer and the first n-type nitride semiconductor layer is smaller than a difference of lattice constant between the second buffer layer and the n-type nitride semiconductor layer,
wherein the third buffer layer includes AIN, and
wherein the first buffer layer includes a silicon layer.