1. 1 Fig. 7 Measured I–V characteristics of LED-I, II, and III. 0.35 A 3.23V 3.22V 3.41V

2. 2 Fig. 8 Life tests of relative luminous intensity measured from these LEDs, normalized to their respective initial readings. Average 350mA 室溫下量 測 5000hEL decresed LED-I366.5mW280.4mW24% LED-II271.8mW191.3mW30% LED-III185.1mW84mW55% 76% 70% 45%

3. 3 Conclusion 1)By flipping the LEDs, one can also shorten the thermal path between the active light emitting region and the heat sink. 2)In other words,we can increase the output power of the power FC LEDs by about 35% by roughening the backside surface of the sapphire substrate.