Light-emitting device having a support substrate and inclined sides
A light-emitting device capable of improving light extraction efficiency is provided. This light-emitting device comprises a support substrate set on a side opposite to a light emission surface and a semiconductor element layer, bonded to the support substrate, having a side surface inclined by a prescribed angle with respect to at least the normal of the light emission surface.
1. A light-emitting device comprising:
a support substrate;
a nitride-based semiconductor element layer on the support substrate, having a first surface which is a light emission surface and a second surface which faces the support substrate, the semiconductor element layer having an active layer having a third surface which faces the light emission surface and a fourth surface which faces the support substrate, the third and fourth surfaces opposite to each other, a first semiconductor layer between the first surface and the third surface, and a second semiconductor layer between the second surface and the fourth surface, wherein the light emission surface emits light to be created in the active layer; and
a reflecting film between the support substrate and the second semiconductor layer, wherein
the second surface is bonded to the support substrate through the reflecting film,
the first semiconductor layer has a thickness from the light emission surface to the third surface, and the second semiconductor layer has a thickness from the second surface to the fourth surface,
the thickness of the first semiconductor layer is greater than the thickness of the second semiconductor layer,
the semiconductor element layer has a side surface inclined with respect to the light emission surface such that the semiconductor element layer is tapered toward the light emission surface, the inclined side surface being inclined linearly and continuously extending from an edge of the second surface to an edge of the light emission surface,
the reflecting film has a fifth surface in contact with the second surface, and a sixth surface opposite to the fifth surface, the reflecting film having a side surface which extends from an edge of the fifth surface to an edge of the sixth surface and is inclined with respect to the inclined side surface of the semiconductor element layer, the inclined side surface of the semiconductor element layer extending to reach the fifth surface, and
the semiconductor element layer has a first angle formed by the inclined side surface of the semiconductor element layer and the light emission surface, the reflecting film has a second angle formed by the side surface of the reflecting film and the fifth surface, and the first angle is greater than the second angle.
2. The light-emitting device according to claim 1 , wherein the side surface of the semiconductor element layer inclined with respect to the light emission surface includes a side surface of the active layer.
3. The light-emitting device according to claim 1 , wherein the reflecting film is bonded to an upper surface of the support substrate through solder or through conductive paste, and the semiconductor element layer is formed on the reflecting film.
4. The light-emitting device according to claim 1 , wherein the reflecting film includes an Ag layer.
5. The light-emitting device according to claim 1 , wherein
an n-side electrode is formed on the semiconductor element layer closer to the light emission surface, and
the n-side electrode comprises an ohmic electrode layer, a barrier metal layer and a pad metal layer successively from the side closer to the semiconductor element layer.
6. The light-emitting device according to claim 5 , wherein the ohmic electrode layer is formed by an Al layer, the barrier metal layer is formed by a Pt or Ti layer, and the pad metal layer is formed by an Au or Au—Sn layer.
7. The light-emitting device according to claim 1 , wherein
the first semiconductor layer has an n-type contact layer, and
the second semiconductor layer has a p-type contact layer and a cap layer,
the cap layer being between the p-type contact layer and the active layer.
8. The light-emitting device according to claim 1 , wherein the light emission surface has a corrugated region.
9. The light-emitting device according to claim 8 , wherein an n-side electrode is located in the corrugated region.
10. The light-emitting device according to claim 1 , wherein the support substrate is a conductive substrate.
11. The light-emitting device according to claim 1 , wherein the support substrate consists of any semiconductor of Si, SiC, GaAs, and ZnO, any metal of Al, Fe—Ni and Cu—W, or a metal and a metal oxide of Cu—CuO.
12. The light-emitting device according to claim 7 , wherein the cap layer consists of an AlGaN layer.
13. The light-emitting device according to claim 1 , wherein the first semiconductor layer comprises a cladding layer and a contact layer.
14. The light-emitting device according to claim 1 , wherein the second semiconductor layer comprises a cladding layer and a contact layer.
15. The light-emitting device according to claim 1 , wherein the second semiconductor layer comprises a cladding layer and a cap layer.
16. The light-emitting device according to claim 1 , wherein the second semiconductor layer comprises a contact layer and a cap layer.
17. The light-emitting device according to claim 1 , wherein
the fifth surface is parallel to the light emission surface.
18. The light-emitting device according to claim 1 , wherein
the side surface of the reflecting film extends in a direction perpendicular to the fifth surface.
19. The light-emitting device according to claim 1 , wherein
the fifth surface is parallel to the light emission surface, and
the side surface of the reflecting film extends in a direction perpendicular to the fifth surface.