Synthesis and characterization of p-type transparent conducting Ni1-xRuxO (0 ≤x ≤ 0.1) films prepared by pulsed laser deposition

Abstract Highly crystalline Ni1-xRuxO films have been prepared via a pulsed laser deposition technique using a Q-switching Nd:YAG laser. The impact of the substitution of Ni2+ ions with Ru4+ ions on the lattice constants and sizes of the NiO crystals was explored by the X-ray diffraction. The surface topography and the grain growth at various Ru ion substitutions have been examined by the atomic force microscopy and scanning electron microscopy. The elemental composition was determined by the energy dispersive spectroscopy, while the influence of Ru ions on the Ni-O and O-O vibration modes was studied by the Raman spectroscopy. The optical properties were investigated by the UV–vis spectroscopy. The I-V characteristics, electrical resistivity, hole mobility and carrier concentrations have been measured. The developed films revealed optical transparency exceeding 97% along the visible region. These films showed a decrease of the optical bandgap from 3.4 to 2.8 eV as the Ru ion content increased from 0 to 10 at%. The doping of NiO with 10 at% of Ru ions causes a decrease of the resistivity to 5 × 10−5 Ω cm, an increase of the mobility to 210 cm2 V−1 s−1 and an increase of the carrier concentration to 3.8 × 1020 cm−3. These unique features make Ru-doped NiO films promising for a replacement of n-type ITO and FTO in optoelectronic applications.