Led element and method for producing same

Abstract

An LED element includes a substrate, a semiconductor lamination part that includes a light-emitting layer formed on a front surface of the substrate, a reflecting portion formed on a back surface of the substrate, and an electrode formed on the semiconductor lamination part. The electrode includes a diffusion electrode layer formed on the semiconductor lamination part and a moth-eye layer which is formed on the diffusion electrode layer and of which the front surface forms the transmissive moth-eye surface having depression parts or projection parts formed with a period smaller than twice the optical wavelength of the light emitted from the light-emitting layer.

1 . An LED element comprising:
 a substrate;   a semiconductor lamination part that includes a light-emitting layer formed on a front surface of the substrate;   a reflecting portion formed on a back surface of the substrate; and   an electrode formed on the semiconductor lamination part, wherein the electrode includes a diffusion electrode layer formed on the semiconductor lamination part and a moth-eye layer which is formed on the diffusion electrode layer and of which the front surface forms the transmissive moth-eye surface having depression parts or projection parts formed with a period smaller than twice the optical wavelength of the light emitted from the light-emitting layer, and   the moth-eye layer is formed of a material which has a smaller extinction coefficient than a material that forms the diffusion electrode layer with respect to the light emitted from the light-emitting layer and has approximately the same index of refraction as the material that forms the diffusion electrode layer.   
     
     
         2 . The LED element according to  claim 1 , wherein
 the diffusion electrode layer is formed of ITO, and   the moth-eye layer is formed of ZrO 2 .   
     
     
         3 . The LED element according to  claim 1 , wherein
 the substrate is formed of sapphire,   a front surface of the sapphire substrate forms a verticalizing moth-eye surface in which a plurality of depression parts or projection parts are disposed with a period larger than twice an optical wavelength of the light emitted from the light-emitting layer and smaller than a coherence length,   the verticalizing moth-eye surface is configured to reflect and transmit light incident on the verticalizing moth-eye surface from the semiconductor lamination part side,   in an angle range exceeding a critical angle, an intensity distribution of the light extracted by reflection from the verticalizing moth-eye surface at the semiconductor lamination part side is inclined closer to a direction vertical to an interface between the semiconductor lamination part and the sapphire substrate than an intensity distribution of the light incident on the verticalizing moth-eye surface at the semiconductor lamination part side,   in an angle range exceeding the critical angle, an intensity distribution of the light extracted by transmission from the verticalizing moth-eye surface at the sapphire substrate side is inclined closer to the direction vertical to the interface than an intensity distribution of the light incident on the verticalizing moth-eye surface at the semiconductor lamination part side,   the LED element includes a reflecting portion that reflects light having transmitted through the verticalizing moth-eye surface,   the LED element includes a transmissive moth-eye surface having depression parts or projection parts formed with a period smaller than twice the optical wavelength of the light emitted from the light-emitting layer, and   the light of which the intensity distribution is adjusted so as to be inclined closer to the direction vertical to the interface by reflection and transmission at the verticalizing moth-eye surface is extracted outside the element in a state where the Fresnel reflection at the transmissive moth-eye surface is suppressed.   
     
     
         4 . The LED element according to  claim 3 , wherein reflectivity of the reflecting portion increases as an angle comes closer to the direction vertical to the interface.