Nitride semiconductor light-emitting device
View Patent ↗In a nitride semiconductor light-emitting device having an active layer between an n-type nitride semiconductor layer and a p-type nitride semiconductor layer, the active layer has a multiple quantum well structure including a plurality of In x Ga 1-x N (0<x≦1) quantum well layers and a plurality of In y Ga 1-y N (0≦y<1) barrier layers stacked alternately, and at least one of the plurality of barrier layers has a super-lattice structure in which a plurality of barrier sub-layers having mutually different In composition ratios are stacked periodically.
1. A nitride semiconductor light-emitting device having an active layer between an n-type nitride semiconductor layer and a p-type nitride semiconductor layer, wherein
said active layer comprises a multiple quantum well structure including a plurality of In x Ga 1-x N (0<x≦1) quantum well layers and a plurality of In y Ga 1-y N (0≦y<1) barrier layers stacked alternately;
at least one of said plurality of barrier layers comprises a super-lattice barrier structure in which a plurality of barrier sub-layers having mutually different In composition ratios are stacked periodically in said one of said plurality of barrier layers; and
a barrier layer of said plurality of barrier layers that is in contact with said p-type nitride semiconductor layer consists of a single layer.
2. The nitride semiconductor light-emitting device according to claim 1 , wherein
among said plurality of barrier layers, a barrier layer other than the one in contact with said p-type nitride semiconductor layer has said super-lattice barrier structure.
3. The nitride semiconductor light-emitting device according to claim 1 , wherein
the barrier layer having said super-lattice structure includes a first barrier sublayer of In y1 Ga 1-y1 N (0≦y1<1) and a second barrier sub-layer of In y2 Ga 1-y2 N (y1<y2<1).
4. The nitride semiconductor light-emitting device according to claim 3 , wherein
at least one of said quantum well layers has an In composition ratio larger than that of any of said barrier sub-layers included in said barrier layer having said super-lattice structure.
5. The nitride semiconductor light-emitting device according to claim 3 , wherein
in said barrier layer having said super-lattice structure, said first barrier sub-layer has a larger thickness compared to a thickness of said second barrier sub-layer.
6. The nitride semiconductor light-emitting device according to claim 5 , wherein
said first barrier sub-layer has a thickness in a range of 2 to 10 nm, and the second barrier sub-layer has a thickness in a range of 1 to 3 nm.
7. The nitride semiconductor light-emitting device according to claim 1 , wherein
said n-type nitride semiconductor layer includes an n-side super-lattice layer in contact with said active layer; and
the n-side super-lattice layer includes an n-side super-lattice sub-layers of In z1 Ga 1-z1 N (0<z1<1) and of In z2 Ga 1-z2 N (0≦z2<1) stacked alternately.
8. The nitride semiconductor light-emitting device according to claim 7 , wherein
at least one of said quantum well layers has an In composition ratio larger than that of any of said n-side super-lattice sub-layers included in said n-side super-lattice layer.
9. The nitride semiconductor light-emitting device according to claim 7 , wherein
in said n-side super-lattice layer, said n-side super-lattice sub-layer having relatively smaller In composition ratio has larger thickness compared to the one having relatively larger In composition ratio.
10. The nitride semiconductor light-emitting device according to claim 7 , wherein
said n-side super-lattice sub-layer having relatively smaller In composition ratio has a thickness in a range of 5 to 20 nm and the one having relatively larger In composition ratio has a thickness in a range of 1 to 5 nm.