In this paper, blue-light InGaN/GaN light-emitting diodes were deposited on sapphire substrate by the Metal Organic Chemical Vapor Deposition (MOCVD) to investigate the properties of blue LEDs with various well thickness having different indium composition. Structural properties of LEDs was studied by high-resolution X-ray diffraction (HRXRD), Photoluminescence (PL) and ultraviole (UV). Our aim is to increase the quality of the LED structure by taking advantage of the mosaic structure calculations. The use of LED in commercial areas has increased. But, there are great difficulties in preventing defects. Lateral and vertical crystal size, dislocations, tilt and twist properties are investigated with HR-XRD device by Vegard and William hall semi-experimental methods. While dislocation value of the first sample is lower than first sample with less indium content ration, stress value of first sample is higher than second sample. In addition, The twist angle of first sample is lower. This shows that while the structure is crystallized, the tension is much greater, which is an interesting result. This is due to the mismatch when the diode is cooled to lower temperatures than the growth temperature.