US Patent 10002991 Light-emitting element

A light-emitting element, comprises a light-emitting stack comprising an active layer; a window layer on the light-emitting stack, wherein the window layer has a surface opposite to the light-emitting stack; and an insulative layer on the surface, wherein the surface comprises a cavity and the insulative layer substantially conformally covering the cavity, and wherein the insulative layer has a first refractive index equal to or smaller than 1.4.