GaN/Si(111) epilayer based on low temperature Al/N and AlGaN/GaN superlattice for light emitting diodes

The various buffer layer structures have been investigated to decrease the dislocation density of GaN/Si(111) epilayer for light emitting diodes using TEM, SEM and double crystal X-ray diffraction. Low temperature AlN/AlGaN with 10 period AlGaN/GaN superlattice has been shown to be effective in reducing the dislocation density and can improve the crystal quality. The full width at half maximum (FWHM) is 611 arcsec. The surface pit density is greatly reduced and the GaN/Si(111) epilayer is free of crack. In addition, the dislocation bending and pairing with equivalent neighboring dislocation is responsible for reducing the dislocation density.