Abstract: Transmission electron microscope (TEM) measurements performed on InGaN/GaN multiple-quantum-well (MQW) deposited Silicon substrates have been investigated.By taking high-resolution transmission electron microscopy (HRTEM) imagery,electron diffraction contrast imagery, and electron diffraction image in precincts between the Si substrate and the AlN buffer area,and also taking Two-beam electron diffract contrast imagery around the quantum well area,we have researched the characteristics of dislocation.In addition,we take the image of materials before and after saturated KOH solution’s cauterization by field emission scanning electric microscope(SEM).It is discovered that the AIN buffer layer is of porous structure,and that a great deal of incomplete dislocation parallel to the interface was found between the buffer layer and extension.The average density of dislocation reaches 1e8cm-2 in the high -temperature GaN layer,which is in accordance with the density of hexagonal etch pits by scanning electric microscope (SEM).Much dislocation below the quantum well was found to be so bent up to 90° that the dislocation density was reduced more through the quantum well.Moreover,edge dislocation accounts for the largest part among all the line dislocations,and mixed dislocation is second,but screw dislocation is hardly found in the observed area.Therefore,we conclude that the porous structure of low-temperature ALN buffer’s enables the extension layer to develop under the ELO model,which leads to a massive dislocation bend below the quantum well and then the density of the penetrating dislocation is reduced.

Key words: MQW, Si substrate, dislocation, TEM, SEM