Effect of Si doping in wells of AlGaN/GaN superlattice on the characteristics of epitaxial layer

AlGaN/GaN superlattice grown on the top of GaN buffer induces the broadening of the full width at half maximum of (102) and (002) x-ray diffraction rocking curves. With the increase of Si-doped concentration in GaN wells, the full width at half maximum of the (102) rocking curves decreases, while that of the (002) rocking curves increases. Significant increase of the full width at half maximum of the (002) rocking curves when the doping concentration reaches 2.5?10¹⁹ cm^-3 indicates the substantial increase of the inclined threading dislocation. High level doping in the AlGaN/GaN superlattice can greatly reduce the biaxial stress and optimize the surface roughness of the structures grown on the top of it.