A flip-chip LED and a method for forming the LED are disclosed. The method includes: providing a substrate and depositing on the substrate an epitaxial layer including, from the bottom upward, an n-type GaN layer, a multi-quantum well active layer, and a p-type GaN layer; etching the epitaxial layer to form an array of openings exposing the n-type GaN layer; forming a first metal layer on the p-type GaN layer; annealing the first metal layer to induce self-assembly thereof; etching the p-type GaN layer by using the first metal layer as a mask such that an array of holes formed therein; and depositing a second metal layer over the array of holes, the second metal layer and the first metal layer form a metal reflector layer. The design can result in an improvement in the light extraction efficiency of the LED.