Reduction of dislocations in GaN epilayers grown on Si(111) substrate using SixNy inserting layer

Abstract

High-quality GaN films have been grown on Si(111) substrate by metalorganic chemical vapor deposition using a SixNy inserting layer. Due to the large difference of lattice constant and thermal expansion coefficient between GaN and Si,GaN growth on Si(111) substrate usually leads to an initially high dislocation density and cracks. It is found that the SixNy inserting layer plays a very important role in the enhancement of crystal quality and surface morphology of GaN films. The crystalline quality of overlying GaN layer grown on SixNy inserting layer depends on the deposition time of SixNy inserting layer. The high-resolution x-ray diffraction results show that the dislocation density in GaN epilayer decreases with increasing SixNy growth time. It was confirmed that the misfit dislocations in the GaN films with 5min deposition time for SixNy inserting layer almost stop at the SixNy inserting layer by transmission electron microscope measurements.