Reflection high energy electron diffraction investigation and comparison of the initial stage during molecular beam epitaxy of AlN on Si(111) and Si(110) substrates

The onset of AlN nucleation on Si(111) and Si(110) surfaces during gas source molecular beam epitaxy with ammonia was carried out by reflection high energy electron diffraction. Exposing the clean Si surfaces to NH3 flux at 600°C yields the formation of crystalline Si3 N₄ on both (111) and (110) surfaces. An 8×8 Si3 N₄ structure was observed for the Si(111) surface. On the Si(110) surface a 2.87 Å periodic structure was observed for electron beam directed along [001] azimuth and 2.46 Å periodic structure for the [1- 12] azimuth. Together, these periodic structures confirm the formation of Si₃ N₄ (0001) plane on both Si(111) and Si(110) surfaces.