High Brightness GaN-on-Si Based Blue LEDs Grown on 150 mm Si Substrates Using Thin Buffer Layer Technology

The commercial adoption of GaN-on-Si light emitting diode (LED) chip technology is lagging behind incumbent sapphire substrates due to significantly longer growth time and poorer crystalline quality. To address these challenges, we report on the growth of high-quality crack-free InGaN/GaN LED structure on 150 mm Si (111) substrate using thin buffer layer technology. The total epilayer thickness is only 3.75μm, offering significant growth time savings and faster manufacturing process throughput. A SiNx interlayer is inserted in the buffer layer to promote lateral overgrowth and improve material quality, resulting in full width at half maximum (0002) and (10-12) of 380 and 390 arcsec, respectively. Reducing dislocation density and optimizing KOH roughening of the n-GaN layer is found to be critical toward improving device performance. The devices were processed as 1 × 1 mm² vertical thin film dies and mounted into a conventional 3535 package with silicone dome lens. The result is a light output power of 563 mW and an operating voltage of 3.05 V, corresponding to a wall-plug-efficiency of 52.7% when driven at 350 mA. These results attest the feasibility of thin buffer GaN-on-Si technology for solid state lighting applications.