GaN-based light emitting diodes (LEDs) grown on 4-in. Si (111) substrate by metal–organic chemical vapor deposition have been systematically characterized. The significantly smooth surface of the sample has been confirmed by an atomic force microscope. In X-ray diffraction measurement, two kinds of fringe peaks were observed, which are believed to originate from the strained-layer superlattice (SLS) and multiple quantum wells. Moreover, from cross-sectional scanning electron microscope images of the sample, it is found that the interfaces of SLS are smooth. The 100-pair AlN/GaN SLS can be employed to modulate the strain between the GaN layer and substrate, resulting in the improvement of GaN crystalline quality. The full width at half maximum of ω-scan of the GaN (0002) diffraction is around 630ʺ. In addition, the device properties have been investigated in detail, and the maximum light output power can reach 2.02 mW with a high saturation injection current of 320 mA.