Method for making a light emitting diode having three dimensional nano-structures

A method for making a light emitting diode, comprising steps of:

• providing a substrate having a first surface;
• forming a first semiconductor layer, an active layer and a second semiconductor pre-layer on the first surface;
• applying a patterned mask layer on a second semiconductor pre-layer surface, wherein the patterned mask layer comprises a plurality of linear walls aligned side by side, and a groove is defined between each adjacent linear walls to form an exposed portion of the second semiconductor pre-layer surface;
• etching the exposed portion of the second semiconductor pre-layer surface along a first direction to form two sidewalls in the second semiconductor pre-laver covered by the plurality of linear walls, and etching the two sidewalls along a second direction, and removing the patterned mask layer to form a plurality of three-dimensional nano-structures, wherein the first direction is perpendicular to the second semiconductor pre-layer surface, the second direction is paralleled to the second semiconductor pre-layer surface, and a cross-section of each three-dimensional nano-structure is a convex arc shape;
• removing the substrate to form an exposed first semiconductor layer surface located away from the active layer;
• covering the exposed first semiconductor layer surface by a first electrode;
• and
• electrically connecting a second electrode with the second semiconductor pre-layer.