Highly efficient InGaN/GaN blue LED on 8-inch Si (111) substrate

Abstract

We have grown LED structures on top of a robust n-type GaN template on 8-inch diameter silicon substrates achieving both a low dislocation density and a 7 um-thick template without crack even at a sufficient Si doping condition. Such high crystalline quality of n-GaN templates on Si were obtained by optimizing combination of stress compensation layers and dislocation reduction layers. Wafer bowing of LED structures were well controlled and measured below 20 μm and the warpage of LED on Si substrate was found to strongly depend on initial bowing of 8-inch Si substrates. The full-width at half-maximum (FWHM) values of GaN (0002) and (10-12) ω-rocking curves of LED samples grown on 8-inch Si substrates were 220 and 320 arcsec. The difference between minimum and maximum of FWHM GaN (0002) was 40 arcsec. The dislocation densities were measured about 2~3×10⁸/cm² by atomic force microscopy (AFM) after in-situ SiH4 and NH₃ treatment. The measured quasi internal quantum efficiency of 8-inch InGaN/GaN LED was ~ 90 % with excitation power and temperature-dependent photoluminescence method. Under the un-encapsulated measurement condition of vertical InGaN/GaN LED grown on 8-inch Si substrate, the overall output power of the 1.4×1.4 mm² chips representing a median performance exceeded 484 mW with the forward voltage of 3.2 V at the driving current of 350 mA.