Method for making light emitting diode

A method for making a light emitting diode comprising:

• providing a substrate having an epitaxial growth surface;
• growing a buffer layer on the epitaxial growth surface, a first semiconductor layer on a surface of the buffer layer, an active layer on a surface of the first semiconductor layer, and a second semiconductor layer on a surface of the active layer in sequence, wherein the first semiconductor layer, the active layer, and the second semiconductor layer cooperatively constitutes a source layer;
• disposing a third optical symmetric layer on a surface of the second semiconductor layer away from the substrate, wherein a refractive index of the third optical symmetric layer is in a range from about 1.2 to about 1.5;
• forming a metallic layer on a surface of the third optical symmetric layer away from the substrate;
• disposing a fourth optical symmetric layer on a surface of the metallic layer away from the substrate, wherein a refractive index of the fourth optical symmetric layer is in a range from about 1.2 to about 1.5;
• forming a first optical symmetric layer on a surface of the fourth optical symmetric layer away from the substrate, wherein a refractive index difference between the first optical symmetric layer and the source layer is smaller than or equal to 0.3;
• exposing the first semiconductor layer by removing the substrate and the buffer layer;
• and
• applying a first electrode on an exposed surface of the first semiconductor layer, and applying a second electrode electrically connected with the second semiconductor layer.