1. 1 Al 2 O 3 sapphire 50nm GaN buffer layer at 550 。 C 3μm Si-doped n + -GaN at 1050 。 C MQW at 770 。 C 50nm Mg-doped p-Al 0.15 Ga 0.85 N EBL at 1050 。 C 1050 。 C 0.25μm Mg-doped p-GaN at 1050 。 C Si-doped n + -InGaN–GaN SPS 15nm ITO 1 nm/200 nm Ni/Ag Reflective mirror N-pad (Ti/Al/Ti/Au) Bump Si submount Sn/Au (15 μm /5 μm ) Well : 3nm In 0.23 GA 0.77 N Barriers : 7nm GaN Well : 5Å In 0.23 GA 0.77 N Barriers : 5Å GaN Structure SiO 2 Passivation

2. 2 Experiments Fig. 1 Schematic diagrams of (a) LED-I with rough sapphire backside surface. (b) LED-II with conventional flat sapphire backside surface. (c) LED-III NFC power LEDs with Al backside reflector. 1x1 mm 2 Chip size

3. 3 Results and Discussion Fig. 2 Top-view SEM micrographs of (a) LED-I and (b) LED-II.