| 摘要 |
PROBLEM TO BE SOLVED: To prevent deterioration in crystal quality of an active layer to improve brightness by constituting a light reflection multi-layer film of a plurality of layers with two kinds of materials having different refractive indexes as a pair and by placing thicker pairs closer to the active layer. SOLUTION: The LED 100 comprises DBR 12 with an n-type AlGaInP layers 12a, 12b different in composition ratio laminated on an n-type GaAs substrate 11. Thickness of the layers 12a, 12b is such that for example thickness of a lowermost layer of the layer 12a is (λ/4n1 )×(1-DD2 ) and thickness of an upper most layer is (λ/4n1 )×(1+DD1 ) where refractive indexes of the respective layers are n1 , n2 , light emission wavelength from an active layer is λ, and changing ratios of the uppermost and lowermost layers are DD1 , DD2 , respectively. Similarly, thickness of a lowermost layer of the layer 12b is (λ/4n2 )×(1-DD2 ) and thickness of an uppermost layer is (λ/4n2 )×(1+DD2 ). |
