| 摘要 |
PROBLEM TO BE SOLVED: To provide a light emitting element that is improved in light emitting efficiency from a light emitting layer and light output and reduced in heat rate by forming a crystalline layer on a substrate having a close refractive index to that of the crystalline layer. SOLUTION: In this light emitting element 1, the light emitting layer 4 is formed by epitaxially growing a crystalline GaN layer 3 (n=2.4) on an SiC substrate 2 (n=2.5), and electrodes 5 and 6 are provided on the bottom face of the crystalline layer 3 with the top faces of the electrodes 5 and 6 on the substrate 2 side and the bottom faces of the electrodes 5 and 6 on the crystalline layer 3 side. In addition, the SiC substrate 2 is formed in a regular quadrangular pyramid shape by obliquely shaving off the four sides of the upper surface of the substrate 2. Since the refractive indexes of the substrate 2 and light emitting layer 4 are almost equal to each other, the light from the layer 4 is not confined in the interface between the substrate 2 and layer 4 and almost all of the light passes through the interface as it is. In the interface between the substrate 2 and air, the rate of the light getting in the critical angle becomes larger, because the four sides of the upper surface of the substrate 2 are obliquely shaved off. Consequently, the external radiant efficiency of the element 1 for primary light increases and that of the element 1 for secondary and after secondary light also increases. Therefore, the light emitting efficiency from the light emitting layer 4 is improved and, accordingly, the external quantum efficiency of the element 1 can also be improved remarkably. |
