Properties Of Nickel Oxide Thin Films Research Articles

Optical properties of NiO thin films fabricated by electron beam evaporation

Nickel oxide (NiO) thin films were deposited onto quartz substrates by the electron beam deposition technique, and obtained high crystal quality after annealing at 1173 K. The structural and microstructural properties of the films were studied by X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. We focus on the optical characterization of the films, indicating the enhancement of the crystal quality, which was confirmed by the photoluminescence and Raman spectrum. Furthermore, PL studies exhibited room temperature emission at 377 nm, and also shown high ultraviolet/visible rejection ratio (>100).

CHARACTERIZATION OF NICKEL OXIDE THIN FILM — DC REACTIVE MAGNETRON SPUTTERING

Nickel oxide ( NiO ) thin films were deposited on glass substrates by reactive direct current (DC) magnetron sputtering of a Ni target in an Ar / O 2 mixture. The effect of thickness (0.2 μm, 0.4 μm and 1 μm) on the structural and surface morphological properties of NiO thin films was investigated. These films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The films were cubic NiO , with preferred orientation in the (111) direction at lower deposition time (10 mins). At higher deposition time (60 mins) the preferred orientation shifted to (200) plane. Electrochemical behavior of NiO thin films for different thickness samples were analyzed between the electrode potential ‑0.2 and 0.8 V vs scanning calomel electrode (SCE) in both anodic and cathodic directions and the current responses were measured.

Nickel–lithium oxide alloy transparent conducting films deposited by spray pyrolysis technique

In this research, nickel oxide (NiO) transparent semiconducting films are prepared by spray pyrolysis technique on glass substrates. The effect of Ni concentration in initial solution and substrate temperature on the structural, electrical, thermoelectrical, optical and photoconductivity properties of NiO thin films are studied. The results of investigations show that optimum Ni concentration and suitable substrate temperature for preparation of basic undoped NiO thin films with p-type conductivity and high optical transparency is 0.1 M and 450 °C, respectively. Then, by using these optimized deposition parameters, nickel–lithium oxide ((Li:Ni)O x ) alloy films are prepared. The XRD structural analysis indicate the formation of the cubic structure of NiO and (Li:Ni)O x alloy films. Also, in high Li doping levels, Ni 2O 3 and NiCl 2 phases are observed. The electrical measurements show that the resistance of the films decreases with increasing Li level up to 50 at%. For these films, the optical band gap and carrier concentration are obtained to be 3.6 eV and 10 15–10 18 cm −3, respectively.

Structural, electrical and mechanical properties of NiO thin films grown by pulsed laser deposition

Nickel oxide (NiO) thin films were prepared by reactive pulsed laser deposition on thermally oxidized Si substrates in 10Pa oxygen pressure. The substrate temperature during deposition was varied and its influence on the structural, electrical and nanomechanical properties was studied. It was proved that the structural properties were affected by the increase of substrate temperature improving the crystalline structure. Furthermore, a higher substrate temperature resulted in a thicker NiO film, which was attributed to an increased grain size. This effect influenced the electrical properties, too. Resistivity measurements showed that it increased with the increase of substrate temperature. For the first time, the nanomechanical properties of NiO films were studied. The formation and improvement of crystalline structure affected the nanomechanical properties. Nanoindentation testing of NiO thin films revealed an increase of hardness (H) and elastic modulus (E) and a decrease of surface roughness when increasing the substrate temperature.

Comparison of the physico-chemical properties of NiO thin films deposited by chemical bath deposition and by spray pyrolysis

Nickel oxide (NiO) thin films were obtained by two methods: chemical bath deposition (CBD) and spray pyrolysis. During the CBD deposition process, the bath was heated at 100 °C. The CBD as-deposited films corresponded to 3Ni(OH) 2·2H 2O. After an annealing time of 96 h at 350 °C, they became NiO. For the spray deposition, the nickel chloride hexahydrate (NiCl 2·6H 2O) was chosen as precursor, the glass substrates were heated at 350 °C. All the films were p-type semiconductors with a band gap of 3.5 eV. The X-ray diffraction diagrams revealed that all the films are crystallized in the cubic NiO phase with the expected value for the lattice parameters. Nevertheless, the orientation and the size of the grains depend on the deposition method. The films are oriented along the (1 1 1) plane in the case of spray, while they are oriented in the (1 1 1) and (2 0 0) planes in the case of CBD. The electron probe microanalysis and the X-ray photoelectron spectroscopy was used to measure the composition of the films. The X-ray photoelectron spectroscopy shows the presence of hydroxyl groups at the surface of the films, while the electron probe microanalysis shows that the films are stoichiometric in the bulk. The scanning electron microscope microphotographs show that all the films exhibit a rough surface with a presence of microstructural features in the case of CBD films. These properties are desired for an eventual application in microcrystalline solar cells.