Light-emitting diode (LED) packages with various heat spreaders were developed to examine the heat dissipation property of sapphire-based LEDs. A cap-shaped copper-diamond sheet was fabricated by composite electroplating and directly contacted to the sapphire surface to enhance heat dissipation from the chip. The thermal diffusivity of the copper-diamond sheet was 0.7179 cm 2/s, as measured using the laser-flash method. LEDs with the copper-diamond sheet presents low surface temperature (49C at 700 mA injecting current) and low thermal resistance (5.8 K/W). These findings suggest that the copper-diamond sheet helped reduce LED thermal resistance, and thereby prevented heat accumulation. The LED package also exhibited high light output power.