Structural characterization of undoped and Si doped GaN on Si (111)

The efficiency of Si doping and AIN as buffer layer to improve the structural quality of GaN layers grown by molecular beam epitaxy on (111) Si substrates is studied. Dislocations, planar defects and inversion domains are present in these layers. The density and distribution of such defects are found to depend on the Si doping. The dislocation density decreases with Si doping. The sizes and misorientation of the subgrains that constitute the mosaic structure of GaN depend on the Si doping and determine the dislocation distribution in the grown layer. The planar defect density increases with Si doping while the inverted domain density decreases as re Si doping increases.