Thin-film InGaN multiple-quantum-well light-emitting diodes transferred from Si (111) substrate onto copper carrier by selective lift-off

Crack-free thin-film InGaN multiple-quantum-well light-emitting diodes (LEDs) were successfully transferred from the original Si (111) substrate onto copper carrier by means of metal-to-metal bonding and the selective lift-off (SLO) technique using wet-chemical etching. Crystalline quality was investigated by x-ray diffraction and photoluminescence measurements. No deterioration was found in the thin film after substrate removal due to the fact that the SLO technique minimizes the residual strain relaxation. Substrate removal eliminates not only the substrate absorption but also the large band offset between the AlN buffer layer and substrate. In conjunction with inserting a metal reflector between the LED structure and the copper carrier, the performances of the LED fabricated on the substrate removal region were significantly improved. The operating voltage at 20 mA and the series resistance was 3.6 V and 27 Ω , respectively. The optical power revealed an increase of 49% compared to the LED before substrate removal.