The influence of an SixNy interlayer on a GaN film grown on an Si(111) substrate

A method to drastically reduce dislocation density in a GaN film grown on an Si(111) substrate is newly developed. In this method, the SixNy interlayer which is deposited on an AlN buffer layer in situ is introduced to grow the GaN film laterally. The crack-free GaN film with thickness over 1.7 micron is successfully grown on an Si(111) substrate. A synthesized GaN epilayer is characterized by X-ray diffraction (XRD), atomic force microscope (AFM), and Raman spectrum. The test results show that the GaN crystal reveals a wurtzite structure with the < 0001 > crystal orientation and the full width at half maximum of the X-ray diffraction curve in the (0002) plane is as low as 403 arcsec for the GaN film grown on the Si substrate with an SixNy interlayer. In addition, Raman scattering is used to study the stress in the sample. The results indicate that the SixNy interlayer can more effectively accommodate the strain energy. So the dislocation density can be reduced drastically, and the crystal quality of GaN film can be greatly improved by introducing an SixNy interlayer.