Enhanced Heat Dissipation of High-Power InGaN Blue Laser Diode Through Diamond Substrates

Heat accumulation seriously affects the electro-optical conversion efficiency of high-power InGaN blue laser diodes (LDs). In this letter, diamond substrates metallized by direct plating copper (DPC) process were proposed to enhance the heat dissipation of high-power blue LDs. The thermal resistance of diamond substrate is only 0.665 K/W. The blue LDs packaged with diamond substrate achieve excellent optical and thermal performances. The electro-optical conversion efficiency of blue LDs packaged with diamond substrate reaches up to 44.1% at an operating current of 2.0 A, which is 17.6% and 16.1% higher than that of blue LDs packaged with AlN substrates (~37.5%) and SiC substrates (~38.0%), respectively. Under a high current of 4.0 A, the surface temperature of blue LDs packaged with diamond substrate is only 79.9°C at a maximum light power of 7.4 W, which was verified by simulation and experiments. It can be seen that the diamond substrate packaging is an efficient approach to enhance heat dissipation of high-power devices.