Semiconductor light emitting device
According to one embodiment, in a light emitting device, a substrate is transparent to a wavelength of emitted light. A first dielectric layer is formed in a first region on the substrate, and has a refractive index smaller than a refractive index of the substrate. A second dielectric layer is formed in a second region on the substrate surrounding the first region, and has a refractive index larger than the refractive index of the substrate. A first semiconductor layer is formed on the first dielectric layer, the second dielectric layer and the substrate. A second semiconductor layer is formed on the first semiconductor layer, and includes an active layer having a PN junction.
1. A semiconductor light emitting device, comprising:
a substrate;
a first dielectric layer formed in a first region on the substrate, and having a refractive index smaller than a refractive index of the substrate;
a second dielectric layer formed in a second region on the substrate surrounding the first region, and having a refractive index larger than the refractive index of the substrate;
a first semiconductor layer formed on the first dielectric layer, the second dielectric layer and the substrate;
a second semiconductor layer; and
an active layer interposed between the first semiconductor layer and the second semiconductor layer.
2. The semiconductor light emitting device according to claim 1 , wherein the substrate is of a sapphire, the first dielectric layer is of a silicon oxide, the second dielectric layer is of a silicon nitride, and the first semiconductor layer and the second semiconductor layer each are of a nitride-based group III-V compound semiconductor.
3. The semiconductor light emitting device according to claim 1 , wherein the first dielectric layer includes a plurality of islands formed in a scattered manner in the first region, and the second dielectric layer includes a plurality of islands formed in a scattered manner in the second region.
4. The semiconductor light emitting device according to claim 3 , wherein the islands have any one of a circular shape, a polygonal shape and a stripe shape.
5. The semiconductor light emitting device according to claim 1 , wherein the first dielectric layer has a plurality of openings formed in a scattered manner in the first region, and the second dielectric layer has a plurality of openings formed in a scattered manner in the second region.
6. The semiconductor light emitting device according to claim 5 , wherein the openings have any one of a circular shape, a polygonal shape and a stripe shape.
7. The semiconductor light emitting device according to claim 1 , wherein a side surface of each of the first dielectric layer and the second dielectric layer is such an inclined surface that the first dielectric layer or the second dielectric layer has a width becoming larger from a first semiconductor layer-side portion toward a substrate.
8. The semiconductor light emitting device according to claim 1 , wherein the first semiconductor layer is a semiconductor layer which is grown selectively on the substrate with the first dielectric layer and the second dielectric layer used as masks, and is further grown in the lateral direction so that growing portions of the semiconductor layer unite together.
9. The semiconductor light emitting device according to claim 1 , wherein the substrate is transparent to a wavelength of light emitted from the active layer.