Abstract: The microstructure of an InGaN/GaN multiple quantum well (MQW) LED on Si (111) substrate is characterized using transmission electron microscopy (TEM) and double crystal X-ray diffraction (DCXRD).High-resolution TEM shows that there is no amorphous layer at the AlN/Si interface.However,stacking faults in the GaN film appear close to the GaN/AlN interface.A very sharp interface between the InGaN and GaN layers reveals the good quality of the MQW material.In addition,TEM and XRD indicate that the dislocation density in the n-GaN layer near the MQW is on the order of 1E8cm-2,and the major dislocation is pure edge dislocation (b=1/3〈11-20〉).

Key words: GaN,  Si substrate,  LED,  dislocation,  TEM,  DCXRD