Gallium nitride-based flip-chip light-emitting diode with double reflective layers on its side and fabrication method thereof

A fabrication method for a gallium nitride (GaN) based flip-chip light-emitting diode (LED) with double reflective layers on its side, comprising:

• 1) forming a buffer layer and an epitaxial layer on a sapphire substrate, the epitaxial layer comprising an N-GaN layer, a multiple-quantum-well layer and a P-GaN layer;
• 2) forming a transparent conductive layer on the P-GaN layer;
• 3) mask etching a portion of the mesa with the transparent conductive layer such that the N-GaN layer is exposed;
• 4) cutting the epitaxial layer and the transparent conductive layer such that the epitaxial layer and the transparent conductive layer have a sloping side;
• 5) forming a distributed Bragg reflector (DBR) over the side of the epitaxial layer and the transparent conductive layer, the DBR comprising alternating layers with a high refractive index and with a low refractive index;
• 6) forming a metal reflective layer on the DBR;
• 7) forming a P-type ohmic contact electrode on the transparent conductive layer;
• 8) forming an N-type ohmic contact electrode on the exposed N-GaN layer, thereby finishing fabrication of a GaN-based LED substrate;
• 9) providing a heat dissipation substrate, and forming a metal conductive layer and a ball bonder on the heat dissipation substrate for eutectic soldering;
• 10) soldering the GaN-based LED substrate to the heat dissipation substrate;
• and
• 11) thinning and polishing the sapphire substrate, and dicing to obtain separate LED chips.