Nitride semiconductor light-emitting device and method for producing the same
A nitride semiconductor light-emitting device includes an n-type nitride semiconductor layer, a V pit generation layer, an intermediate layer, a multiple quantum well light-emitting layer, and a p-type nitride semiconductor layer provided in this order. The multiple quantum well light-emitting layer is a layer formed by alternately stacking a barrier layer and a well layer having a bandgap energy smaller than that of the barrier layer. A V pit is partly formed in the multiple quantum well light-emitting layer, and an average position of starting point of the V pit is located in the intermediate layer.
1. A nitride semiconductor light-emitting device comprising an n-type nitride semiconductor layer, a V pit generation layer, an intermediate layer, a multiple quantum well light-emitting layer, and a p-type nitride semiconductor layer provided in this order, wherein
said multiple quantum well light-emitting layer is a layer formed by alternately stacking a barrier layer and a well layer having a bandgap energy smaller than that of the barrier layer,
a V pit is partly formed in said multiple quantum well light-emitting layer, and
an average position of starting point of said V pit is located in said intermediate layer.
2. A nitride semiconductor light-emitting device comprising an n-type nitride semiconductor layer, a V pit generation layer, an intermediate layer, a lower multiple quantum well light-emitting layer, an upper multiple quantum well light-emitting layer, and a p-type nitride semiconductor layer provided in this order, wherein
said upper multiple quantum well light-emitting layer is a layer formed by alternately stacking an upper barrier layer and an upper well layer having a bandgap energy smaller than that of the upper barrier layer,
said lower multiple quantum well light-emitting layer is a layer formed by alternately stacking a lower barrier layer and a lower well layer having a bandgap energy smaller than that of the lower barrier layer, and at least said lower barrier layer is doped with an n-type impurity,
an average n-type doping concentration of said lower multiple quantum well light-emitting layer is higher than an average n-type doping concentration of said upper multiple quantum well light-emitting layer,
a V pit is partly formed in said upper multiple quantum well light-emitting layer, and
an average position of starting point of said V pit is located in said intermediate layer or in said lower multiple quantum well light-emitting layer.
3. The nitride semiconductor light-emitting device according to claim 1 or 2 , wherein n-type doping concentration in said V pit generation layer is significantly higher than n-type doping concentration in the uppermost surface of said n-type nitride semiconductor layer.
4. The nitride semiconductor light-emitting device according to claim 3 , wherein n-type doping concentration in said V pit generation layer is greater than or equal to 5×10 18 cm −3 .
5. The nitride semiconductor light-emitting device according to claim 1 or 2 , wherein an In composition rate in said V pit generation layer is higher than an In composition rate in the uppermost surface of said n-type nitride semiconductor layer.
6. The nitride semiconductor light-emitting device according to claim 5 , wherein
said V pit generation layer contains an n-type impurity, and
said V pit generation layer has a composition of In x Ga 1-x N (0.1≦x≦0.2).
7. The nitride semiconductor light-emitting device according to claim 1 or 2 , wherein thickness of said V pit generation layer is greater than or equal to 5 nm.
8. The nitride semiconductor light-emitting device according to claim 1 or 2 , wherein thickness of said intermediate layer is greater than or equal to 40 nm.
9. The nitride semiconductor light-emitting device according to claim 1 or 2 , wherein said intermediate layer is a layer formed by alternately stacking a wide bandgap layer and a narrow bandgap layer having a bandgap energy smaller than that of the wide bandgap layer.
10. The nitride semiconductor light-emitting device according to claim 2 , wherein the number of barrier layers in said upper multiple quantum well light-emitting layer is greater than or equal to 4.