Nitride semiconductor light emitting device

Abstract

A nitride semiconductor light emitting device includes n-type and p-type nitride semiconductor layers, an active layer disposed between the n-type and p-type nitride semiconductor layers and having a structure in which a plurality of quantum barrier layers and one or more quantum well layers are alternately stacked, and an electron blocking layer disposed between the active layer and the p-type nitride semiconductor layer. The electron blocking layer has greater bandgap energy than a quantum barrier layer adjacent to the electron blocking layer among the plurality of quantum barrier layers, and has a net polarization equal to or smaller than that of the quantum barrier layer adjacent thereto. The nitride semiconductor light emitting device can achieve high efficiency in every current region by minimizing a net polarization mismatch between a quantum barrier layer and an electron blocking layer.

1 . A nitride semiconductor light emitting device comprising:
 n-type and p-type nitride semiconductor layers;   an active layer disposed between the n-type and p-type nitride semiconductor layers and having a structure in which a plurality of quantum barrier layers and one or more quantum well layers are alternately stacked; and   an electron blocking layer disposed between the active layer and the p-type nitride semiconductor layer,   wherein the electron blocking layer has greater bandgap energy than a quantum barrier layer adjacent to the electron blocking layer among the plurality of quantum barrier layers, and has a net polarization equal to or smaller than that of the quantum barrier layer adjacent thereto.   
     
     
         2 . The nitride semiconductor light emitting device of  claim 1 , wherein the electron blocking layer has a net polarization which is smaller than or equal to that of GaN and is greater than that of Al 0.25 Ga 0.75 N. 
     
     
         3 . The nitride semiconductor light emitting device of  claim 2 , wherein the electron blocking layer has bandgap energy having the same magnitude as that of Al 0.25 Ga 0.75 N. 
     
     
         4 . The nitride semiconductor light emitting device of  claim 1 , wherein the electron blocking layer has a net polarization which is equal to that of the quantum barrier layer adjacent to the electron blocking layer among the plurality of quantum barrier layers. 
     
     
         5 . The nitride semiconductor light emitting device of  claim 1 , wherein a net polarization mismatch at an interface between the electron blocking layer and the quantum barrier layer adjacent to the electron blocking layer is smaller than a net polarization mismatch between GaN and Al x Ga (1−x) N (0.1≦x≦0.25). 
     
     
         6 . The nitride semiconductor light emitting device of  claim 5 , wherein the net polarization mismatch at the interface between the electron blocking layer and the quantum barrier layer adjacent to the electron blocking layer is half the net polarization mismatch between GaN and Al x Ga (1−x) N (0.1≦x≦0.25). 
     
     
         7 . The nitride semiconductor light emitting device of  claim 1 , further comprising a substrate for growth contacting the n-type nitride semiconductor layer,
 wherein the n-type nitride semiconductor layer is formed on a polar surface of the substrate.   
     
     
         8 . The nitride semiconductor light emitting device of  claim 7 , wherein the n-type nitride semiconductor layer is formed on a C (0001) plane of a sapphire substrate. 
     
     
         9 . A nitride semiconductor light emitting device comprising:
 n-type and p-type nitride semiconductor layers;   an active layer disposed between the n-type and p-type nitride semiconductor layers and having a structure in which a plurality of quantum barrier layers and one or more quantum well layers are alternately stacked; and   an electron blocking layer disposed between the active layer and the p-type nitride semiconductor layer,   wherein the electron blocking layer has a constant energy level of a conduction band.