Thermally stable mirror structures for vertical-conducting GaN/Mirror/Si light-emitting diodes

Abstract

Vertical-conducting GaN/mirror/Si light-emitting diodes (LEDs) with thermally stable mirrors have been fabricated using a combination of wafer-bonding and laser liftoff techniques. The thermal stabilities of NiO-Ag, NiO-Ag-Ni, and NiO-Au-Ag mirrors and their effects on the performance of mirror-substrate LEDs were studied. It is found that the NiO-Ag-Ni mirror presents the best performance, where the specific contact resistance and the reflectivity can achieve 5.1 x 10(-3) ohm.cm(2) and 92% at 470 nm after oxidation annealing at 500 degrees C for 10 min. The top Ni layer could protect the Ag mirror from clustering during the thermal treatment process. The output powers of the GaN-sapphire and GaN/mirror/Si LEDs with NiO-Au-Ag and NiO-Ag-Ni mirrors show 4.5, 4.3, and 13 mW, respectively.