Fabrication of p-pad-up GaN-based thin-film light-emitting diodes with electroplated metallic substrates

A novel method has been developed to fabricate p-pad-up GaN-based thin-film light-emitting diodes (TF-LEDs) with electroplated metallic substrates. First, a Ni/Ag/Ni/Au mirror severed as p-contact is totally covered by an insulating SiN_x layer, which separates n-contact from the p-contact. Then, a copper layer connected with the n-contact was electroplated to a thickness of about 120 μm as a metallic substrate for the light-emitting diode epitaxial wafer. After removal of the original sapphire substrate with an excimer laser, the exposed GaN layers were selectively etched to the p-contact. Finally, a Cr/Pt/Au multilayer was deposited onto the p-contact to complete the whole p-pad-up TF-LED structure. The p-pad-up TF-LEDs exhibit superior electrical and optical properties at high driven current densities.