White light emitting device
View Patent ↗The invention relates to a monolithic white light emitting device using wafer bonding or metal bonding. In the invention, a conductive submount substrate is provided. A first light emitter is bonded onto the conductive submount substrate by a metal layer. In the first light emitter, a p-type nitride semiconductor layer, a first active layer, an n-type nitride semiconductor layer and a conductive substrate are stacked sequentially from bottom to top. In addition, a second light emitter is formed on a partial area of the conductive substrate. In the second light emitter, a p-type AlGaInP-based semiconductor layer, an active layer and an n-type AlGaInP-based semiconductor layer are stacked sequentially from bottom to top. Further, a p-electrode is formed on an underside of the conductive submount substrate and an n-electrode is formed on a top surface of the n-type AlGaInP-based semiconductor layer.
1. A white light emitting device comprising:
a submount substrate having a p-side lead terminal and an n-side lead terminal formed thereon;
a first light emitter including a p-type nitride semiconductor layer, a first active layer, an n-type nitride semiconductor layer and an insulating substrate stacked sequentially from bottom to top, the p-type nitride semiconductor layer connected to the p-side lead terminal and the n-type nitride semiconductor layer connected to the n-side lead terminal;
a metal layer formed on a partial area of the insulating substrate;
a second light emitter formed on the metal layer, bonded to a partial area of the metal layer, the second light emitter including a p-type A 1 GaInP-based semiconductor layer, a second active layer and an n-type AlGaInP-based semiconductor layer stacked sequentially; and
first p- and n-electrodes connected to the p- and n-type nitride semiconductor layers of the first light emitter, respectively;
a second p-electrode connected to another area of the metal layer; and
a second n-electrode connected to the n-type AlGaInP-based semiconductor layer of the second light emitter.
2. The white light emitting device according to claim 1 , wherein the submount substrate comprises a silicon substrate or a metal substrate.
3. The white light emitting device according to claim 1 , wherein the metal layer comprises a high reflectivity metal selected from a group consisting of Al, Ag, Rh, Ru, Pt, Pd and alloys thereof.
4. The white light emitting device according to claim 1 , wherein the insulating substrate of the first light emitter comprises a sapphire substrate.
5. The white light emitting device according to claim 1 , wherein the partial area of the insulating substrate of the first light emitter is smaller than a remaining area of the insulating substrate.
6. The white light emitting device according to claim 1 , wherein the insulating substrate has a rough pattern formed on an area where the second light emitter is not formed.
7. The white light emitting device according to claim 1 , wherein the first active layer is adapted to generate light of a wavelength of about 450 nm to 475 nm and the second active layer is adapted to generate light of a wavelength of about 550 nm to 600 nm.
8. The white light emitting device according to claim 1 , wherein the first active layer includes two active layers for generating light of a wavelength of about 450 nm to 475 nm and light of a wavelength of about 510 nm to 535 nm, respectively, and
wherein the second active layer is adapted to generate light of a wavelength of about 600 nm to 635 nm.