Gallium nitride-based compound semiconductor light emitting device
An object of the present invention is to provide a gallium nitride-based compound semiconductor light emitting device having excellent light extraction efficiency and a high emission output in which a planar shape is a rectangular shape with vertical and longitudinal sides each having a different length. The present light emitting device comprises a substrate and a gallium nitride-based compound semiconductor layer formed on the substrate, wherein a planar shape is a rectangular shape with vertical and longitudinal sides each having a different length, and a side surface of the gallium nitride-based compound semiconductor layer is not vertical to a principal surface of the substrate.
1. A light emitting device comprising a sapphire substrate having a C-plane upper surface and a gallium nitride-based compound semiconductor layer formed on the upper surface of the substrate, wherein a planar projection shape of said light-emitting device is a rectangular shape with rectangular long and short sides each having a different length, said light emitting device having a side end surface at each of the rectangular long sides and a side end surface at each of the rectangular short sides, a side end surface at a rectangular long side of the gallium nitride-based compound semiconductor layer corresponds to a plane direction of A-plane in a gallium nitride single crystal lattice, and the side end surface of the rectangular long side of the gallium nitride-based compound semiconductor layer corresponding to a plane direction of A-plane is inclined with respect to a principal surface of the substrate such that a cross sectional area of the gallium nitride-based compound semiconductor layer parallel to the principle substrate surface becomes smaller towards the principle substrate surface, and wherein an angle θ between the inclined side surface of the gallium nitride-based compound semiconductor layer and a principle surface of the substrate is less than 90° .
2. The light emitting device according to claim 1 , wherein the rectangular long side of the gallium nitride-based compound semiconductor layer has a length of from 50 μm to 2,000 μm.
3. The light emitting device according to claim 1 , wherein the ratio of a rectangular short side to the rectangular long side of the gallium nitride-based compound semiconductor layer is from 1:10 to 4:5.
4. The light emitting device according to claim 1 , wherein a positive electrode bonding pad is located in a center of the rectangular long side of the gallium nitride-based compound semiconductor layer.
5. A lamp comprising the light emitting device according to claim 1 .
6. An electronic equipment comprising the lamp according to claim 5 assembled therein.
7. A machinery comprising the electronic equipment according to claim 6 assembled therein.
8. The light emitting device according to claim 1 , wherein the gallium nitride-based compound semiconductor layer has a planar upper surface.