Optimization design of cup-shaped copper heat spreaders for high-power InGaN/sapphire LEDs

Abstract

To improve light extraction efficiency and heat dissipation of sapphire-based light-emitting diodes (LEDs), we develop and optimize copper heat spreader which was electroformed in close contact with sapphire. On the basis of simulation results, an LED with copper lowers junction temperature when compared with the LED without copper. In addition, a copper-surrounded LED with protruded bottom surface exhibits almost the same thermal performance as that with flat bottom surface. In practical fabrication, all the LED samples with copper show significant reduction in junction temperature form 150.4°C for the original LED to less than 100°C at injection current of 1 A (∼ 3 W/mm2). The encapsulated LED at the same driven current yields an output power of ∼700 mW, which is 2.7 times higher than that of the original LED without copper.