Nitride semiconductor light emitting device and fabrication method thereof
The present invention relates to a nitride semiconductor light emitting device including: a substrate having a predetermined pattern formed on a surface thereof by an etch; a protruded portion disposed on a non-etched region of the substrate, and having a first buffer layer and a first nitride semiconductor layer stacked thereon; a second buffer layer formed on the etched region of the substrate; a second nitride semiconductor layer formed on the second buffer layer and the protruded portion; a third nitride semiconductor layer formed on the second nitride semiconductor layer; an active layer formed on the third nitride semiconductor layer to emit light; and a fourth nitride semiconductor layer formed on the active layer. According to the present invention, the optical extraction efficiency of the nitride semiconductor light emitting device can be enhanced.
1. A light emitting device comprising:
a substrate having a plurality of patterns;
a first conductive semiconductor layer on a buffer layer, wherein the first conductive semiconductor layer includes first to third GaN-based layers, wherein the first GaN-based layer includes Si dopant, the second Ga-based layer includes a dopant having a lower concentration of Si than the first GaN-based layer, and the third GaN-based layer includes In material, wherein the first conductive semiconductor layer further comprises a fourth GaN-based layer including Al material, and wherein the fourth GaN-based layer has a planar surface;
an active layer on the third GaN-based layer of the first conductive semiconductor layer, wherein the active layer comprises a single quantum well layer or a multi quantum well layer of In x Ga 1-x N/In y Ga 1-y N; and
a second conductive semiconductor layer on the active layer.
2. The light emitting device according to claim 1 , wherein the substrate includes one of sapphire, silicon carbide, silicon, or GaAs.
3. The light emitting device according to claim 1 , further comprising a contact layer on the second conductive semiconductor layer.
4. The light emitting device according to claim 3 , wherein the first conductive semiconductor layer and the contact layer have a first conductivity and the second conductive semiconductor layer has a second conductivity, and
wherein the first conductivity and the second conductivity are different from each other.
5. The light emitting device according to claim 1 , further the buffer layer on the substrate.
6. The light emitting device according to claim 5 , wherein the buffer layer includes one of a stack structure of AlInN/GaN, a super lattice structure of InGaN/GaN, a stack structure of In x Ga 1-x N/GaN, a stack structure of Al x In y Ga 1−(x+y) N/In x Ga 1-x N/GaN, an undoped GaN layer, or doped GaN layer.
7. The light emitting device according to claim 1 , further comprising a transparent electrode on the second conductive semiconductor layer.
8. The light emitting device according to claim 1 , wherein the second conductive semiconductor layer includes a super lattice structure.
9. The light emitting device according to claim 8 , wherein one period of the super lattice structure has a thickness less than 250 Å.
10. The light emitting device according to claim 1 , wherein the third GaN-based layer has a content of an Indium of less than 5%.
11. The light emitting device according to claim 1 , wherein the first conductive semiconductor layer includes an Al-doped layer.
12. The light emitting device according to claim 1 , wherein a width of an upper portion of the pattern is narrower than a width of a lower portion of the pattern.
13. The light emitting device according to claim 1 , further at least one of the buffer layer and a fifth GaN-based layer on the patterns to form a protrusion shape.
14. The light emitting device according to claim 13 , wherein the fifth GaN-based layer includes In material.