Patent ID: 7554122

Claim:
A nitride semiconductor light emitting device for generating light containing a wavelength component in an ultraviolet region, the device comprises: a first conductivity type nitride semiconductor layer provided on a support base; a second conductivity type nitride semiconductor layer provided on the support base; an active region provided between the first conductivity type nitride semiconductor layer and the second conductivity type nitride semiconductor layer, the active region including an In X1 Al Y1 Ga 1-X1-Y1 N well layer (1>X 1 >0 and 1>Y 1 >0) and an In X2 Al Y2 Ga 1-X2-Y2 N barrier layer (1>X 2 >0 and 1>Y 2 >0); and an In X3 Al Y3 Ga 1-X3-Y3 N buffer layer (1>X 3 >0 and 1>Y 3 >0)provided between the active region and the first conductivity type nitride semiconductor layer, a proportion X 1 of indium in the In X1 Al Y1 Ga 1-X1-Y1 N well layer being smaller than a proportion X 3 of indium in the In X3 Al Y3 Ga 1-X3-Y3 N buffer layer, a proportion X 2 of indium in the In X2 Al Y2 Ga 1-X2-Y2 N barrier layer being smaller than the proportion X 3 of indium in the In X3 Al Y3 Ga 1-X3-Y3 N buffer layer, and the In X3 Al Y3 Ga 1-X3-Y3 N buffer layer being in direct physical contact with the active region.