In our study, transparent and conductive films of NiO
were successfully deposited by sol-gel technology. NiO
films were obtained by spin coating on glass and Si substrates. The vibrational, optical, ...and electrical properties were studied as a function of the annealing temperatures from 200 to 500 °C. X-ray Photoelectron (XPS) spectroscopy revealed that NiO was formed at the annealing temperature of 400 °C and showed the presence of Ni
states. The optical transparency of the films reached 90% in the visible range for 200 °C treated samples, and it was reduced to 76-78% after high-temperature annealing at 500 °C. The optical band gap of NiOx films was decreased with thermal treatments and the values were in the range of 3.92-3.68 eV. NiO
thin films have good p-type electrical conductivity with a specific resistivity of about 4.8 × 10
Ω·cm. This makes these layers suitable for use as wideband semiconductors and as a hole transport layer (HTL) in transparent solar cells.
This work presents a facile sol-gel method for the deposition of ZnO and ZnO:Mg films. The films are spin coated on silicon and quartz substrates. The impact of magnesium concentrations (0, 0.5, 1, 2 ...and 3 wt%) and post-annealing treatments (300-600 °C) on the film's structural, vibrational and optical properties is investigated. Undoped ZnO films crystallize in the wurtzite phase, with crystallite sizes ranging from 9.1 nm (300 °C) to 29.7 nm (600 °C). Mg doping deteriorates the film crystallization and shifting of 002 peak towards higher diffraction angles is observed, indicating the successful incorporation of Mg into the ZnO matrix. ZnO:Mg films (2 wt%) possess the smallest crystallite size, ranging from 6.2 nm (300 °C) to 25.2 nm (600 °C). The highest Mg concentration (3 wt%) results into a segregation of the MgO phase. Lattice constants, texture coefficients and Zn-O bond lengths are discussed. The diminution of the
lattice parameter is related to the replacement of Zn
by Mg
in the ZnO host lattice. The vibrational properties are studied by Fourier transform infrared (FTIR) spectroscopy. IR lines related to Mg-O bonds are found for ZnO:Mg films with dopant concentrations of 2 and 3 wt%. The optical characterization showed that the transmittance of ZnO:Mg thin films increased from 74.5% (undoped ZnO) to about 89.1% and the optical band gap energy from 3.24 to 3.56 eV. Mg doping leads to a higher refractive index compared to undoped ZnO films. The FESEM (field emission scanning electron microscopy) technique is used for observation of the surface morphology modification of ZnO:Mg films. The doped ZnO films possess a smoother grained surface structure, opposite to the wrinkle-type morphology of undoped sol-gel ZnO films. The smoother surface leads to improved transparency of ZnO:Mg films.
TiO2 and TiO2-NiO films were successfully derived by a sol–gel dip coating technology. The impact of the thermal treatments (300–600 °C) on the structural, optical and electrochromic properties was ...investigated. X-ray diffraction (XRD) analysis showed that TiO2 films were polycrystalline and evolved in the anatase phase. The composite TiO2-NiO films, treated at annealing temperatures below 500 °C, contained anatase titania, a small inclusion of cubic NiO and an amorphous fraction. The formation of NiTiO3 was exposed after the highest annealing at 600 °C. The presence of Ti-O-Ni bonds was determined in the composite films by Fourier-transform infrared (FTIR) spectroscopy. The optical properties and the optical band gap of TiO2-NiO films were investigated and discussed. The transparency of the electrochromic TiO2-NiO films was 76.8 and 78.3% in the 380–700 nm spectral range after film thermal treatments at 300 and 500 °C. NiO incorporation led to the narrowing of the optical band gap. The electrochromic (EC) properties of the composite films were improved compared to TiO2 films. They had higher diffusion coefficients. Their color efficiencies are 37.6 (550 nm) and 52.2 cm2/C (600 nm).
A sol–gel deposition approach was applied for obtaining nanostructured Li-doped ZnO thin films. ZnO:Li films were successfully spin-coated on quartz and silicon substrates. The evolution of their ...structural, vibrational, and optical properties with annealing temperature (300–600 °C) was studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV-VIS spectroscopic, and field emission scanning electron microscopic (FESEM) characterization techniques. It was found that lithium doping maintains the wurtzite arrangement of ZnO, with increasing crystallite sizes when increasing the annealing temperature. Analysis of the FTIR spectra revealed a broad main absorption band (around 404 cm−1) for Li-doped films, implying the inclusion of Li into the ZnO lattice. The ZnO:Li films were transparent, with slightly decreased transmittance after the use of higher annealing temperatures. The porous network of undoped ZnO films was transformed to a denser, grained, packed structure, induced by lithium doping.
TiOsub.2 and TiOsub.2-NiO films were successfully derived by a sol–gel dip coating technology. The impact of the thermal treatments (300–600 °C) on the structural, optical and electrochromic ...properties was investigated. X-ray diffraction (XRD) analysis showed that TiOsub.2 films were polycrystalline and evolved in the anatase phase. The composite TiOsub.2-NiO films, treated at annealing temperatures below 500 °C, contained anatase titania, a small inclusion of cubic NiO and an amorphous fraction. The formation of NiTiOsub.3 was exposed after the highest annealing at 600 °C. The presence of Ti-O-Ni bonds was determined in the composite films by Fourier-transform infrared (FTIR) spectroscopy. The optical properties and the optical band gap of TiOsub.2-NiO films were investigated and discussed. The transparency of the electrochromic TiOsub.2-NiO films was 76.8 and 78.3% in the 380–700 nm spectral range after film thermal treatments at 300 and 500 °C. NiO incorporation led to the narrowing of the optical band gap. The electrochromic (EC) properties of the composite films were improved compared to TiOsub.2 films. They had higher diffusion coefficients. Their color efficiencies are 37.6 (550 nm) and 52.2 cmsup.2/C (600 nm).
The structural, vibrational, optical and morphological properties of ZnO:N:F films, obtained by the sol-gel method, were investigated. The effect of single (fluorine, nitrogen) and F, N co-doping and ...thermal treatments (300–600 °C) on the properties of ZnO films was analyzed. X-ray Diffraction (XRD) revealed that ZnO:N:F films crystallized in a polycrystalline wurtzite structure. F and N incorporation changed lattice parameters, crystallite sizes, texture coefficients (TC) and residual stress. TC (002) of ZnO:N:F films increased with annealing, reaching 1.94 at 600 °C lower than the TC (002) of ZnO and ZnO:N films. The shifting of the characteristic absorption bands and/or the appearance of new IR lines were detected for ZnO:N:F samples. The highest transmittance (90.98%) in the visible spectral region was found for ZnO:F films. ZnO:N:F films possessed optical transparency up to 88.18% and their transmittance decreased at the higher annealings. The optical band gap (Eg) values of ZnO:N:F films were changed with fluorine and nitrogen concentrations. The formation of the wrinkle-like structures on the surface of ZnO and ZnO:N films was depicted in Field Emission Scanning Electron Microscopy (FESEM) images. The F, N dual doping modified ZnO morphology and suppressed wrinkle formation.
In this work chemical liquid deposition from sol–gel solutions has been used to obtain thin (Al2O3)x(B2O3)1 − x dielectric films. Passivation of Si surfaces using these films has been studied. ...Morphological properties of thin films deposited on polished Si surfaces have been investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) technique. Their chemical composition, structural and optical features have been analysed by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and ultraviolet‐visible (UV–VIS) spectroscopy. Results, obtained in this work, show that silicon surfaces can be effectively passivated by thin dielectric layers deposited from chemical solutions. The thin dielectric layers developed in his work, can be recommended as back side passivation coating for Si‐based solar cells.
In this work chemical liquid deposition from sol-gel solutions has been used to obtain thin (Al sub(2)O sub(3)) sub(x)(B sub(2)O sub(3)) sub(1-x) dielectric films. Passivation of Si surfaces using ...these films has been studied. Morphological properties of thin films deposited on polished Si surfaces have been investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) technique. Their chemical composition, structural and optical features have been analysed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-VIS) spectroscopy. Results, obtained in this work, show that silicon surfaces can be effectively passivated by thin dielectric layers deposited from chemical solutions. The thin dielectric layers developed in his work, can be recommended as back side passivation coating for Si-based solar cells.
This paper presents new results on the deposition technique and the characterization of thin (ZrO2)x(Al2O3)1-x layers on silicon. The layers were deposited using the chemical solution ...depositionmethod on silicon substrates, and they were then subjected to different temperature treatments. For comparison, pure ZrO2 layers were deposited, too. The chemical composition of (ZrO2)x(Al2O3)1-x layers is determined by Rutherford Back Scattering. The morphology was studied by HRSEM. The addition of Al2O3 makes the layers structurally more homogeneous as compared to those of pure ZrO2. The electric properties of MIS structures were studied. A fixed negative charge and the high dielectric constants are characteristic for these layers. The experimental results are discussed in the context of using them as high-k dielectrics.
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