Progress in research of GaN-based LEDs fabricated on SiC substrate

The influence of buffer layer growth conditions on the crystal quality and residual stress of GaN film grown on silicon carbide substrate is investigated. It is found that the AlGaN nucleation layer with high growth temperature can efficiently decrease the dislocation density and stress of the GaN film compared with AlN buffer layer. To increase the light extraction efficiency of GaN-based LEDs on SiC substrate, flip-chip structure and thin film flip-chip structure were designed and optimized. The fabricated blue LED had a maximum wall-plug efficiency of 72% at 80 mA. At 350 mA, the output power, the V_f, the dominant wavelength, and the wall-plug efficiency of the blue LED were 644 mW, 2.95 V, 460 nm, and 63%, respectively.