Molecular beam epitaxy growth of CuO and Cu2O films with controlling the oxygen content by the flux ratio of Cu/O+

Abstract We have investigated the molecular beam epitaxy (MBE) growth of oxide thin films in ultrahigh vacuum (UHV) using a mass-separated, low-energy, oxygen ion (O + ) beam as an oxygen source. Epitaxial growth of CuO films on unheated (001)MgO substrates at 3×10 -9 Torr was confirmed with an orientation relationship of CuO-(111)∥MgO(001) and CuO[ 1 10]∥MgO[110]. Phase formation of CuO and Cu 2 O was controlled by the flux ratio Cu/O + . The Cu 2 O films were grown at Cu/O + of about 0.6 at 400°C with an orientation relationship of Cu 2 O(110)∥MgO(001) and Cu 2 O[001]∥MgO[110]. The results show that this technique has a capability of adjusting the oxygen content in oxide thin films by flux control during MBE growth in UHV.