Role of Ions in GaAs Film Growth on Si Substrates by Mixed Beams of Ions and Molecules.

Thin GaAs films were grown on Si (001) substrates by Ga and As beams, consisting of low-energy ions and neutral molecules, without thermal cleaning of substrate surfaces and buffer layers. The energy of the ions in the mixed beams had to be higher than 60eV to grow single-crystalline GaAs films on the Si substrates, In this case, the surface of the Si substrates was amorphized by collisions of ions in the mixed beams. The amorphous Si layer was inserted between Si substrates and GaAs films and served as a buffer layer reliving strain due to the large mismatch and the difference in linear expansion between GaAs films and Si substrates.