Properties Of CuO Thin Films Research Articles

Effect of Manganese Contain on the Optical Properties of CuO Thin Films

Copper oxide prepared with various contains of Manganese by chemical spray pyrolysis. Some optical properties are studied from recording the absorption spectra via UV-Visible spectrophotometer in the range of 460-900 nm. The absorbance increased with increasing Mn-contain in the CuO thin films, and the absorption coefficient. Extinction coefficient and refractive index are decreased with increasing Mn-contain in the CuO thin films, also the energy gap shifted from 2 eV to 1.91 eV after 4%Mn additive.

Effect of Manganese Contain on the Optical Properties of CuO Thin Films

Copper oxide prepared with various contains of Manganese by chemical spray pyrolysis. Some optical properties are studied from recording the absorption spectra via UV-Visible spectrophotometer in the range of 460-900 nm. The absorbance increased with increasing Mn-contain in the CuO thin films, and the absorption coefficient. Extinction coefficient and refractive index are decreased with increasing Mn-contain in the CuO thin films, also the energy gap shifted from 2 eV to 1.91 eV after 4%Mn additive.

Modification of electrical and optical properties of CuO thin films by Ni doping

Undoped and Ni-doped CuO thin films were deposited onto glass substrates using a spin-coating technique at different doping concentrations (undoped, 2, 4, 6, and 10 %). X-ray diffraction patterns for undoped and Ni-doped CuO thin films indicated that the films were polycrystalline, with preferential growth in the (002), (111), and (−311) directions. Atomic force microscopy images revealed that the surface morphologies of the films were not uniform. Scanning electron microscopy images confirmed the presence of agglomerated particles on the surfaces; the coverage increased with the doping level. A Hall effect system with a van der Pauw configuration was used to investigate the electrical properties of the CuO films. The free charge carrier concentration decreased and hole mobility increased with increasing Ni concentration, with the exception of the 10 % Ni-doped CuO sample. Ultraviolet–visible spectroscopy measurements of the film samples indicated an average transmittance of 30–40 % in the visible range. The optical band gap decreased slightly for low-level doping and increased from 2.03 to 2.22 eV for 10 % Ni incorporation. The electrical and optical properties of the CuO films were modified by Ni doping, i.e. the band gap decreased and the mobility increased almost linearly, with the exception of the 10 % Ni-doped sample. SEM images of a undoped b 2 % c 4 % d 6 %, and e 10 % Ni-doped CuO thin films.

Effect of Mg doping on Cu2O thin films and their behavior on the TiO2/Cu2O heterojunction solar cells

The present work shows the effect of magnesium doping on structural, optoelectrical and electrical properties of Cu2O thin films prepared by spray pyrolysis. The variation in the concentration of Mg shows significant impact on the final thin film properties, whereas the film doped with 0.5at% of Mg exhibited major property improvements in comparison with the undoped thin film and among the other concentrations tested. This condition was further applied for the deposition of an absorber layer in a heterojunction solar cell array with a gradient in thicknesses of active layers to investigate the impact of changing thicknesses on the PV parameters of the solar cell. TiO2 was used as a window layer and the 0.5at% Cu2O doped film as an absorber layer. The produced heterojunction solar cell array was further exposed to a rapid thermal annealing treatment. The I–V measurements show an open circuit voltage of up to 365mV and a short circuit current density, which is dependent on absorber layer thickness, and reaches to a maximum value of 0.9mA/cm2.

Preparation and Characterization of Nanostructured CuO Thin Films using Sol-gel Dip Coating

Nanostructured CuO thin films were deposited onto quartz substrates by sol-gel dip coating technique. The precursor solution was prepared by dissolving copper acetate powder into isopropanol with molarity of 0.25M. Preheating and annealing temperature were fixed at 250°C and 600°C respectively. This study focused on various film thicknesses by varying the frequent number of deposited layers. The effect of thickness on electrical, surface morphology and optical properties of CuO thin film were studied. The surface morphology was examined using field emission scanning electron microscopy (FE-SEM), surface profiler for thickness measurement, optical properties of CuO thin film were characterized by using ultraviolet- visible spectroscopy (UV-VIS) for transmittance and absorbance, and the electrical property was examined by using two point probes method. The films were found to be denser at higher film thickness due to lesser porous observed on the surface. The thickness of these CuO thin films varied from 87.14 – 253.58 nm and the direct band gap energy was observed in between 1.9 to 2.35 eV. Lowest resistivity was found for sample with a thickness of 253.58 nm.

Effect of thickness on the structural and optical properties of CuO thin films grown by successive ionic layer adsorption and reaction

CuO thin films were synthesised on glass substrates at room temperature using successive ionic layer adsorption and reaction (SILAR) method. The effect of film thickness on characteristic parameters such as the structural, morphological and optical properties of the films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all of the films exhibited polycrystalline structure with monoclinic phases and covered the glass substrates well. The crystalline and morphology of the films improved with increasing film thickness. The optical band gap decreased from 2.03 to 1.79eV depending on the film thickness. The refractive index (n), electron effective mass (me⁎/mo) and static and frequency dielectric constants (εo, ε∞) were determined using the energy band gap values.

Effect of temperature and additive on the structural, morphological and optical properties of Cu2O thin films

In the current work, electrodeposition method has been used to prepare Cu2O thin films on ITO substrates. The bath temperature was controlled from 40 to 80°C and additive concentration varied from 2 to 10mM. The structure, surface morphology and optical properties of the as-prepared films were investigated by X-ray diffractometer (XRD), field-emission scanning electron microscope (SEM), Raman spectrophotometer and UV–visible (vis) spectrophotometer. The morphology of the Cu2O films varies obviously at different bath temperature and additive concentration. Intensity of Raman peaks increase with the increase of KCl concentration. UV–vis absorption spectra measurements have shown the average absorbance for the film deposited at 80°C is higher than those deposited at 40 and 60°C. Meanwhile, average absorbance of the Cu2O thin film deposited at 10mM KCl is larger than those deposited at 2 and 5mM KCl, which should be associated with the morphology.

The effects of thermally-induced biaxial stress on the structural, electrical, and optical properties of Cu2O thin films

The effects of biaxial stress in Cu2O thin films grown by rf magnetron sputtering at different growth temperatures were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), electrical transport, and ellipsometric measurements. A predominant diffraction peak in the XRD patterns corresponds to the (111) plane direction of the Cu2O phase. Biaxial tensile stress was induced by thermal mismatch between the film and substrate and increased with increasing growth temperature. As the growth temperature and biaxial stress increased, the electrical resistivity decreased, while the carrier concentration and Hall mobility both increased. The ellipsometric data were fit using an optical dispersion model, and the decrease in refractive index was attributed to contraction of the lattice parameter with increasing biaxial stress. The optical absorption peaks shifted slightly toward higher energy with increasing stress. Our experimental data suggest that the mechanisms of stress are important for understanding the properties of Cu2O thin films and for the fabrication of devices using them.

Effect of Oxidation Temperature on the Properties of CuO Thin Films Prepared by Thermal Oxidation of Sputtered Cu Thin Films

CuO thin films were obtained through thermal oxidation of dc magnetron sputtered metallic Cu films on glass substrates. Thermal oxidation process was performed in air at temperature ranging 300-500 °C. From XRD patterns, CuO single phase of monoclinic structure was formed at oxidation temperature beyond 450 °C whereas amorphous phase with very small grains was obtained at oxidation temperature below 450 °C. The positive sign of the Hall coefficient confirmed the p-type conductivity in all studied films. From transmission spectra, direct band gap value is varied between 2.17 and 2.83eV. From the transient photoconductivity measurements, persistent photoconductivity (PPC) behavior was observed. The decay current data were better fitted with the multiple exponential functions resulting into five slow decay times. Density of trap states corresponding to its decay time was also evaluated from the decay current data.

Role of materials chemistry on the electrical/electronic properties of CuO thin films

CuO thin films with different levels of compositional deviation from 50:50 stoichiometry have been fabricated using radiofrequency sputtering deposition wherein the sputtering gases consisted of oxygen and argon in various proportions. The microstructures of the thin films were characterized by combining a series of advanced methods including X-ray diffraction, energy dispersive X-ray analysis, scanning and high-resolution transmission electron microscopy, electron energy loss spectroscopy, and high-resolution X-ray photoelectron spectroscopy. The results showed that the chemical states of Cu and O in the thin films depended upon CuO composition and sputtering conditions, so that different levels of Cu vacancies dictated the electrical/electronic properties of the thin films. The ability to control the compound composition and associated alloying chemistry enables tuning of the concentration and mobility of holes in CuO, hence creating alow-cost and environmentally friendly semiconductor from abundant materials. This offers an essential technical basis in engineering photonic devices such as pn or Schottky diodes, thus opening new avenues for economic harvest of solar energy using diodes solely based on sustainable oxides.

Properties of Cu2O Thin Films for All-Oxide Solar Cells

In this work, p-type Cu2O thin films deposited by RF magnetron sputtering for Cu2O based all metal oxide solar cells were studied as a function of oxygen partial pressure ratio at room temperature. The Cu2O (111) x-ray diffraction peaks were indicated as a function of oxygen partial pressure ratio. Optical band gap energies of as-deposited Cu2O thin films ranged from 1.88 to 1.96 eV as a function of oxygen partial pressure ratio. The resistivity and mobility of the p-type Cu2O thin film with an oxygen partial pressure ratio of 2.4% was 2 ×104 Ω·cm and 15.1 cm2/V·s, respectively.

Fabrication and Switching Characterizations of Copper Oxide Thin Films for Applications in Resistive Random Access Memory Devices

Many nonvolatile memory devices such as, ferroelectric random access memory (FeRAM), magnetic random access memory (MRAM), ovonic universal memory (OUM), and resistive random access memory (RRAM) were considerable discussed and investigated. For these nonvolatile memory devices, the RRAM devices will play an important role because of its non-destructive readout, low operation voltage, high operation speed, long retention time, and simple structure. The RRAM devices were only consist of one resistor and one corresponding transistor. In this study, the CuO thin films deposited on ITO/glass and Pt/Ti/SiO2/Si substrates for applications in RRAM devices were produced and investigated. The optimal sputtering conditions of as-deposited CuO thin films were the rf power of 80 W, chamber pressure of 20 mTorr, substrate temperature of 580°C, and an oxygen concentration of 40%. The basic mechanisms for the bistable resistance switching were observed. The electrical and physics properties of CuO thin films for applications in RRAM devices were discussed.

Optical Properties of Cuo Thin Films with Different Concentration by Spray Pyrolysis Method

Optical Properties of Cuo Thin Films with Different Concentration by Spray Pyrolysis Method

The Characteristics of Cu2O Thin Films Deposited Using RF‐Magnetron Sputtering Method with Nitrogen‐Ambient

We investigate the characteristics of Cu2O thin films deposited through the addition of N2 gas. The addition of N2 gas has remarkable effects on the phase changes, resulting in improved electrical and optical properties. An intermediate phase (6CuO·Cu2O) appears at a N2 flow rate of 1 sccm, and a Cu2O (200) phase is then preferentially grown at a higher feeding amount of N2. The optical and electrical properties of Cu2O thin films are improved with a sufficient N2 flow rate of more than 15 sccm, as confirmed through various analyses. Under this condition, a high bandgap energy of 2.58 eV and a conductivity of 1.5×10−2 S/cm are obtained. These high‐quality Cu2O thin films are expected to be applied to Cu2O‐based heterojunction solar cells and optical functional films.

Enhancement in supercapacitive properties of CuO thin films due to the surfactant mediated morphological modulation

The complex hierarchical CuO nanostructures (woolen clumps, stacked nanosheets and nanobuds) have been developed through a chemical bath deposition method using surfactant assisted approach. The morphology of CuO nanostructures can be easily tuned using different surfactants as a soft chemical template. Nanobuds clusters deliver a superior 3D conductive framework, which allows well electrolytic accessible surface area and provides a shortest path for ions. The porous and well defined nanostructure renders a high contact surface area for the intercalation/deintercalation of ions into/out of active materials and reduces the path length for electrolyte ion transport. The maximum specific capacitance of 396Fg−1 at 5mVs−1 is calculated for CuO nanobuds structured electrode. Moreover, all the CuO nanostructures reveal better power performance, excellent rate as well as long term cycling stability. Such a study will encourage for the preparation of 3D nanostructures framework of the other materials using surfactant assisted approach.

Mechanical Properties of Cu₂O Thin Films by Nanoindentation.

In this study, the structural and nanomechanical properties of Cu2O thin films are investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and nanoindentation techniques. The Cu2O thin films are deposited on the glass substrates with the various growth temperatures of 150, 250 and 350 °C by using radio frequency magnetron sputtering. The XRD results show that Cu2O thin films are predominant (111)-oriented, indicating a well ordered microstructure. In addition, the hardness and Young’s modulus of Cu2O thin films are measured by using a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. Results indicated that the hardness and Young’s modulus of Cu2O thin films decreased as the growth temperature increased from 150 to 350 °C. Furthermore, the relationship between the hardness and films grain size appears to closely follow the Hall-Petch equation.

Optical and electrical properties of CuO thin films deposited at several growth temperatures by reactive RF magnetron sputtering

Copper oxide thin films were deposited on glass substrates at various growth temperatures by the reactive radio-frequency magnetron sputtering method. The band gap energy, carrier concentration and figure of merit of the CuO thin films were found to depend significantly on the growth temperature. All of the CuO films, irrespective of growth temperature, showed a monoclinic structure with the main CuO $$\left( {\bar 111} \right)$$ orientation, and the crystallite size, determined by using Scherrer’s formula, was about 50 nm for the thin film deposited at 25 °C. The highest figure of merit occurred for the film grown at 300 °C with an optical transmittance of 62.9% in the wavelength range of 800–1100 nm. The results suggest that the optimum growth temperature for growing high-quality CuO thin films is 300 °C.

Characterization of Cu<sub>2</sub>O Thin Film Grown by Molecular Beam Epitaxy

We report the growth of Cu2O thin films on glass and MgO(100) substrates by molecular beam epitaxy. Crystal orientation of Cu2O thin films on glass substrate were changed from (100) to (111) with increasing the deposition rate. The Cu2O thin films were epitaxially grown on MgO(100) substrate with an orientation relationship of Cu2O(110) // MgO(100). The film quality and electrical properties of Cu2O thin films were changed with deposition rate. The slow deposition rate resulted in high conductivity and mobility, as well as good crystallinity and orientation.

Carrier transport in In-doped CuO thin films

Temperature-dependent conductivity and thermopower measurements are carried out for undoped and In-doped CuO thin films. We investigate the effects of In-doping on carrier transport properties of CuO thin films in the temperature range of 300 < T < 400 K. Carrier transport is dominated by simple thermally activated conduction in the undoped film. On the other hand, small polarons play an essential role in the carrier transport properties in the In-doped films. By increasing the In content, the conduction behaviour transits from adiabatic limit to the non-adiabatic limit, and the conductivity decreases.

Laser Irradiation Effect on Structural and Optical Properties of CuO Thin Films Prepared by Chemical Spray Pyrolysis

substrate at temperature (635 K) by chemical spray pyrolysis technique. The films were annealed with CW diode laser (808 nm) for (1 and 3) min. X-ray diffraction (XRD) was used to study the structure of the films. The patterns showed that the films as-prepared have typical peaks of monoclinic tenorite (CuO), which confirmed by (111) and (111) diffraction peaks. The later peak disappeared with laser annealing for (1 and 3) min and (200) peak appeared. The annealing leads to increase the intensity of (111) diffraction peak. The UV-Vis spectrophotometer was used to study the optical properties of the films. The results showed that the annealing leads to increase the transmittance and decrease the absorbance. The optical energy gap (Eg) of these films is direct, and it increases with increasing the laser exposure time.