Growth of cubic GaN on Si(001) by plasma-assisted MBE

GaN films grown directly on Si(001) by plasma-assisted molecular beam epitaxy are found to undergo a structural phase transformation from epitaxial growth of the cubic (β) phase towards textured growth of the hexagonal (α) phase. The origin of this phase transformation is investigated and identified to be due to the formation of amorphous SixNy material at the GaN/Si interface during the nucleation stage. A GaAs buffer layer overcomes this problem as evidenced by the phase purity of the resulting epitaxial β-GaN films on GaAs/Si(001).