Structural, optical, and electrical properties of unintentionally doped NiO layers grown on MgO by plasma-assisted molecular beam epitaxy

摘要: NiO layers were grown on MgO(100), MgO(110), and MgO(111) substrates by plasma-assisted molecular beam epitaxy under Ni-flux limited growth conditions. Single crystalline with a cube-on-cube epitaxial relationship was confirmed X-ray diffraction measurements for all used conditions except MgO(111). A detailed series MgO(100) prepared using substrate temperatures ranging from 20 °C to 900 °C investigate the influence layer characteristics. Energy-dispersive spectroscopy indicated close-to-stoichiometric an oxygen content of ≈ 47 at. % 50 low high O-flux, respectively. All had root-mean-square surface roughness below 1 nm, measured atomic force microscopy, rougher at or oxygen. Growth led significant diffusion Mg into film. The relative intensity quasi-forbidden one-phonon Raman peak is introduced as gauge crystal quality, indicating highest quality flux temperature, likely due resulting adatom length during growth. optical electrical properties investigated spectroscopic ellipsometry resistance measurements, transparent bandgap around 3.6 eV semi-insulating room temperature. However, changes upon exposure reducing oxidizing gases representative elevated temperature able confirm p-type conductivity, highlighting their suitability model system research oxide-based gas sensing.NiO intro...