Patent ID: 7943927

Claim:
A ZnO based semiconductor light emitting device comprising: a first semiconductor layer containing ZnO 1-x1 S x1 ; a second semiconductor layer formed above said first semiconductor layer and containing ZnO 1-x2 S x2 ; and a third semiconductor layer formed above said second semiconductor layer and containing ZnO 1-x3 S x3 , wherein an S composition x1 of said first semiconductor layer, an S composition x2 of said second semiconductor layer and an S composition x3 of said third semiconductor layer are selected such that (i) an energy of said second semiconductor layer at the lower end of a conduction band becomes lower than both an energy of said first semiconductor layer at the lower end of a conduction band and an energy of said third semiconductor layer at the lower end of a conduction band, and (ii) an energy of said second semiconductor layer at the upper end of a valence band becomes higher than both an energy of said first semiconductor layer at the upper end of a valence band and an energy of said third semiconductor layer at the upper end of a valence band, and wherein the S composition x1 of said first semiconductor layer and the S composition x3 of said third semiconductor layer are 0, and the S composition x2 of said second semiconductor layer is in a range of 0.25<x2<0.6.