CuS Thin Films Research Articles

Comparative investigation on physicochemical and photocatalytic properties of CuS and Al3+ doped CuS thin films

By using the chemical bath approach, CuS, and Al-doped CuS thin films were formed onto glass substrates. To enhance the photocatalytic capabilities of the traditional CdS thin film, Al3+ ions were used as doping element. Investigations were done into how the amount of Al doping affected the physical characteristics of CuS films by varying Al content as 2 wt%, 4 wt%, 6 wt%, and 8 wt%). The bandgap energy, thickness, morphology, and crystalline structure of CuS and Al-doped CuS thin films were examined. By using FTIR and FT-Raman studies, the functional groups contained in the CuS and Al-doped CuS thin films were observed. EDS was used to estimate the elemental components that are present in the prepared thin films. Degradation of the textile dyes rhodamine B (RhB) and methylene blue (MB) was used to examine the photocatalytic characteristics of the produced films. Among the produced films 8 wt% Al-doped CuS thin film showed high efficiency in degradation of both MB (98 %) and RhB (98 %) dyes.

The effect of sputtering power on structural, mechanical, and electrical properties of Copper Selenide Thermoelectric thin films deposited by magnetron sputtering

Copper Selenide (Cu2Se) has received much attention as a potential thermoelectric and environmentally friendly material because of its exceptional thermoelectric performance. This study shows how Cu2Se thin films' structural, morphological, mechanical, and electrical properties are affected by varying the sputtering power deposited by radio frequency magnetron sputtering. By varying the sputtering power, the as-deposited Cu2Se thin film thickness values ranged from 436 to 1139 nm, measured by the stylus profilometer. Grazing incidence X-ray diffraction analysis was conducted to ascertain the phases present in the deposited films. It was observed that at higher sputtering power of 110 W, the Cu2-xSe phase was formed. Field Emission Scanning Electron Microscopy studies revealed that Cu2Se thin films deposited under varying sputtering power possess well-defined crystallinity with uniform distribution over the glass substrate. The grain size of the films increased with an increase in sputtering power. The nanoindentation studies showed that with varying sputtering power from 30 W to 110 W, hardness increased, having a maximum value of 2.4 ± 0.47 GPa for 110W sputtered film. The highest power factor of 15.6 μ W/cmK2 was achieved for a 110 W sputtered sample measured at a temperature of 450 °C, which is higher than that of all Cu2Se thin films, sputtered at different power.

Deposition of stoichiometry – tailored amorphous Cu-S thin films by MOCVD technique

ABSTRACT Deposition technique and associated deposition parameters play significant roles in determining the stoichiometry of thin films, and consequently, their properties. Herein, Cu-S thin films were deposited on a sodalime glass substrate via metal organic chemical vapour deposition (MOCVD) at temperatures between 350 and 450°C using a single solid source precursor. The deposited Cu-S films were characterized using Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectrophotometry, and four-point probe technique. RBS characterization revealed that the films are non-stoichiometry while thickness increased from 480 to 655 nm as deposition temperature increased. SEM revealed micrographs that are temperature-dependent. A direct band gap value between 2.75 and 3.80 eV was obtained as the deposition temperature increased. Electrical characterization showed ohmic characteristics in which, resistivity decreased from 18.50 × 10−3 Ωcm to 8.20 × 10−3 Ωcm as deposition temperature increased.

Flexible oriented α-Cu2Se films and devices with remarkable power factor and output power at near-room temperature

Cu2Se has attracted great attention as a new promising thermoelectric (TE) material because of its high performance, environmentally friendly features and low cost. So far, most studies on Cu2Se focused on the β-phase bulks at medium temperature. However, in terms of commercial applications, α-phase Cu2Se with high TE performance at near-room temperature are highly desired, especially for the flexible thin films which have unique advantages in constructing wearable microelectronic devices. Herein, flexible b-axis oriented α-phase Cu2Se thin films are prepared by pulsed laser deposition (PLD) technology. The in-plane PF of the obtained flexible thin films reaches up to ∼17.6 μW cm−1K−2 at room temperature, which is much higher than that report for Cu2Se random-oriented bulks. In addition, flexible TE thin film devices are developed based on the oriented α-Cu2Se films with ∼3% fluctuation in resistance after bending for 1500 times. The maximum power density of the device is as high as ∼10.2 W m−2 under temperature difference of ∼40 K. Expectedly, the remarkable PF and output power of the thin films and devices as well as the preparation technology with precise controllable proportion will further promote the application of flexible TE materials as self-sufficient energy sources in wearable electronic devices.

Carrier density tuning in CuS nanoparticles and thin films by Zn doping via ion exchange.

Copper sulphide (covellite) nanoplatelets have recently emerged as a plasmonic platform in the near-infrared with ultrafast nonlinear optical properties. Here we demonstrate that the free-carrier density in CuS, which is an order of magnitude lower than in traditional plasmonic metals, can be further tuned by chemical doping. Using ion exchange to replace Cu with an increasing content of Zn in the nanoparticles, the free-hole density can be lowered, resulting in a long-wavelength shift of the localised plasmon resonances from 1250 nm to 1750 nm. The proposed approach provides new opportunities for tuning the plasmonic response of covellite nanocrystals as well as the carrier relaxation time which decreases for lower free-carrier densities.

Study the properties of Cu2Se thin films for optoelectronic applications

Copper selenide (Cu2Se) thin films were prepared by thermal evaporation at RT with thickness 500 nm. The heat-treating for (400 &500) K for the absorber layer has been investigated. This research includes, studying the structural properties of X-ray diffraction (XRD) that show the Cu2Se thin film (Cubic) and has a polycrystalline orientation prevalent (220). Moreover, studying the effect of annealing on their surface morphology properties by using Atomic Force Microscopy AFM. Optical properties were considered using the transmittance and absorbance spectra had been recorded when wavelength range (400 - 1000) nm in order to study the absorption coefficient and energy gap. It was found that these films had allowed direct transition optical band gap which decreases with the increasing effect of annealing, while it increasing with the increase in the annealing temperature at all ratio UV-Visible transmission spectrum. Hall Effect results presented that all thin films have P-type. It is quite possible that the heterojunction (p-Cu2Se/n-Si) solar cell device is a buried. The illumination current- voltage (I-V) characteristics showed that the solar cell, with (t=500 nm and T=500 K ) has highest efficiency (η =1.4 %).

Effect of annealing on chemically deposited Cu2Se thin films

Cu2Se is a promising candidate in the field of photovoltaic and thermoelectric devices. The pristine Cu2Se thin films are observed to be unstable under ambient conditions. One of the instabilities reported in this material is the formation of dendritic structures on the surface. The present work discusses the effect of post-deposition annealing on the dendritic growth formation. The pristine Cu2Se films were vacuum annealed at 60 °C, 80 °C, 100 °C, 150 °C, and 180 °C and the properties of the samples were investigated. The XRD peak profile analysis was done to evaluate the microstructural parameters like crystallite size, microstrain, stress and energy density. The various techniques used for this study include Scherrer method, Modified Scherrer Method, Williamson-Hall Plots, and Size Strain Plot. The modified variants of W–H Plots were employed which included Uniform Deformation Model, Uniform Stress Deformation Model and Uniform Deformation Energy Density Model. In all these cases, the crystallite size was found to increase on annealing. This is attributed to the reduction in defects and dislocations due to annealing of the sample. Microstrain is also observed to increase with the increase in annealing temperature. The calculation of crystallite size and lattice strain using UDM model deviates more from other models. This may be due to the incompatibility of its basic assumption of isotropic strain in UDM model. The W–H plots also suggest the presence of tensile strain in the lattice. The Cu ions in pristine Cu2Se thin films are in a disordered state due to their high mobility and diffusion coefficient. These mobile Cu ions form the centres of anisotropy and participate in dendritic growth formation with suitable stimulants. With an increase in annealing temperature, these ions get ordered due to strain hardening which in turn stabilizes the Cu2Se structure. The minimum temperature required to resist dendritic growth formation was found to be 150 °C. Thus annealing of pristine sample is suggested as a simple but effective method towards stabilization of the matrix. During the annealing process in the temperature range 60 °C–180 °C, it is observed that the optical band gap decreased from 2.2 eV to 1.9 eV.

PREPARATION AND OPTICAL ANALYSIS OF COPPER SULPHIDE THIN FILM USING CHEMICAL BATH DEPOSITION METHOD

Copper Sulphide thin films is a metal usually found in superconducting films, diamond films, among others Solution growth method was used for the preparation of CuS thin films on glass substrates at various temperatures and deposition times. In this research, optical properties of these films were investigated. It is used in ultra violet range and microwave shielding. Best deposition was obtained at 600C. The corresponding 14950 Å film showed 3.7% transmittance at 300 nm and the band gap of the films was within 1.35 – 2.35 eV.

In3+-doped CuS thin films: physicochemical characteristics and photocatalytic property

In3+-doped CuS thin films: physicochemical characteristics and photocatalytic property

Sequentially evaporated layer deposition stack of CuxS thin films for photonics applications

CuxS(x;1,2) layers were grown on thermal annealing of the sequentially evaporated layer deposition (SELD) stack of Cu/S from 373 to 573 K. The thicknesses of the deposited stacks were fixed at 200 and 600 nm. The 300 K deposited layers possess a CuS (covellite) phase and a few impurity peaks of Sulphur (S). The as-deposited films of both thicknesses provided the CuS (covellite) phase with impurity peaks of Sulphur (S). The CuS single phase was observed at 373 and 473 K. The CuS transformed into a copper-rich Cu2S (chalcocite) phase at 523 K, and the same phase continued at 573 K. The Cu2S phase was obtained on re-evaporation of S from CuS at 523 K. An intermediary digenite phase was also spotted at 523 K. The CuS and Cu2S phases were confirmed from the Raman spectra. The oxidation states of Cu and S of the CuS films were also determined from XPS analysis. The Cu 2p and S 2p levels of CuS (covellite) were established using high-resolution XPS spectra. The phase transformation from CuS to Cu2S and change in stoichiometry at higher temperatures give rise to bandgap variation from 2.30 to 1.20 eV for direct and 2.10–1.34 eV for indirect allowed bandgaps. The absorption coefficient (α) for both thickness values is > 1 × 105 cm-1. Further, the 600 nm films provided higher absorption coefficient (α) values than the 200 nm layers. The unique electrical and optical properties and bandgap tuning make CuS and Cu2S thin films suitable for gas sensors, photodetectors, absorber layers in low-cost PV solar cells, and energy storage applications.

Synthesis and characterization of arrested precipitation assembled Cu2Se thin films

Nanostructured thin films of copper selenide (Cu2Se) deposited by arrested precipitation technique (APT) with controlled release of ions at suitable pH=10.5. The deposited Cu2Se films were characterized for optical, structural, and morphological properties. Optical absorption study indicates that the band gap energy (2.26 eV) of material and shows visible radiation absorption. XRD shoe that APT is a favorable technique for the synthesis of pure nanocrystalline Cu2Se thin films with monoclinic crystal structure. An electrochemical impedance spectroscopy analysis confirms the charge transfer resistance. X-ray photoelectron spectroscopy reveals stoichiometry at valance state of Cu2Se.

Synthesis and characterization of arrested precipitation assembled Cu2Se thin films

Nanostructured thin films of copper selenide (Cu2Se) deposited by arrested precipitation technique (APT) with controlled release of ions at suitable pH=10.5. The deposited Cu2Se films were characterized for optical, structural, and morphological properties. Optical absorption study indicates that the band gap energy (2.26 eV) of material and shows visible radiation absorption. XRD shoe that APT is a favorable technique for the synthesis of pure nanocrystalline Cu2Se thin films with monoclinic crystal structure. An electrochemical impedance spectroscopy analysis confirms the charge transfer resistance. X-ray photoelectron spectroscopy reveals stoichiometry at valance state of Cu2Se.

Effect of molar concentration on the structural, linear and nonlinear optical properties of CuS (covellite) thin films

CuS thin films with various molar concentrations at 70 °C temperature were deposited by Chemical Bath Deposition. The effect of molar concentration on the structural, linear optic, nonlinear optic and morphological properties of CuS films were deeply investigated. X-ray diffraction (XRD) analysis exhibited that CuS films were formed in polycrystal structure and hexagonal phase. The fundamental optical parameters of films such as energy band gap, reflection and extinction coefficient were determined with the results of optical transmission and optical absorption by UV–vis spectrophotometer. The energy band gap values were reduced with increasing films thickness. Moreover, the dependence of the optical dielectric constants, loss tangent, optical conductivity, surface and volume energy loss function values on the molar concentrations were studied. Furthermore, the third order nonlinear optical susceptibility and nonlinear refractive index, which is considered to be the base of the first order optical susceptibility with nonlinear optical properties were discussed in detail.

Optical, Structural and Electrical Properties of CuS Thin Film on Dielectric Substrate by Spray Pyrolysis Technique

Abstract: This paper deals with depositing a CuS thin film on a glass substrate at 3800C by using spray pyrolysis method. Its optical properties and electric properties are characterized after cooling the sample. Formation for compound, structure and morphology were studied using x-ray diffraction. The optical study comprised the extraction and analysis of calculated optical constants, such as absorption coefficient (α), transmittance, extinction coefficient (k), which revealed the presence of a direct optical energy band gap of 2.0 eV. The temperature-dependent electrical resistivity with other necessary parameters was systematically studied for CuS film in the present work. Overall study confirmed the semiconducting behavior of the film which is useful for many applications, even when the film is touching the substrate at a micrometer scale with spray pyrolysis. This paper also explores the optical conductivity, dielectric constant, Urbach energy, morphology and thermal activation energy of the CuS film with explaining methodological details. Keywords: Thin film, Spray pyrolysis technique, Electrical and optical properties, XRD.

Au Nanosheets‐Assisted Structural Phase Transitions, In Situ Monitoring of the Enhanced Crystallinity, and Their Effect on the Optical and Dielectric Properties of CuSe/Au/CuSe Thin Films

AbstractHerein, stacked layers of copper selenide thin films comprising Au nanosheets in its structure are fabricated and characterized. The CuSe/Au/CuSe (CAC) thin films are prepared by the thermal evaporation technique under a vacuum pressure of 10−5 mbar. It is shown that Au nanosheets improve the stoichiometric growth of the CuSe thin films and induce the structural phase transitions from cubic to hexagonal. In addition, the in situ monitoring of the structural modifications in the CAC in the temperature range of 293–473 K proves the permanent enhanced crystallinity of the films. Optically, while the Au nanosheets increase the light absorbability and redshifts the energy band gap of CuSe, the in situ heating blueshifts the energy band gap. Moreover, insertion of Au nanosheets between layers of CuSe and heating them at 473 K significantly increase the dielectric constant and the optical conductivity by more than five times. Moreover, the drift mobility of charged carriers, the scattering time at femtosecond level, and the plasmon frequency are remarkably enhanced. Values of plasmon frequency exceed 6.0 GHz nominating the CAC films as signal receivers suitable for 5G technology.

Semiconducting Cu2Se thin films obtained by electrochemical deposition for possible applications in thermoelectric systems

Semiconducting Cu2Se thin films obtained by electrochemical deposition for possible applications in thermoelectric systems

Effect of Molar Concentration on the Structural, Linear and Non-Linear Optical Properties of Cus (Covellite) Thin Films

Effect of Molar Concentration on the Structural, Linear and Non-Linear Optical Properties of Cus (Covellite) Thin Films

Effect of lanthanum substrates on the structural, optical and electrical properties of copper selenide thin films designed for 5G technologies

In this work, copper selenide thin films coated onto glass and transparent lanthanum substrates are studied. The (glass, La)/CuSe thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10−5 mbar are structurally, morphologically, optically, dielectrically and electrically characterized. Lanthanum substrates improved the crystallinity by increasing the crystallite size and decreasing both of the microstrains and defect density of copper selenide. La substrates redshifts the energy band gap and doubled the dielectric constant values. In addition, employing Drude–Lorentz approaches for optical conduction to fit the dielectric constant provided information about the effects of La substrates on the drift mobility, plasmon frequency, free carrier density and scattering times at femtosecond level. The drift mobility increased and the plasmon frequency range is modified when La substrates are used. Verifying impedance spectroscopy tests in the microwave frequency domain have shown the ability of the La(gate)/CuSe/Ag (source) transistors performing as band pass filters. These filters are suitable for 5G technologies. The microwave cutoff frequency reached ~ 5.0 GHz at a notch frequency of 2.80 GHz of the glass/La/CuSe/Ag highpass filters.

Growth of dendritic structures on the surface of copper selenide thin films

Dendritic structures have been extensively studied in the fields of photovoltaics, metallurgy, lasers, welding, and a variety of other applications in recent years. This paper discusses the formation of dendritic structures on the surface of pristine copper selenide thin films. These films were prepared by the Chemical Bath Deposition technique on the ITO substrate. A systematic investigation was carried out to detect the factors which initiate the filamentary growth. The pristine thin films were subjected to various laboratory conditions and the samples were periodically monitored using an optical microscope and SEM imaging. It was noticed that presence of HCl vapour activated the dendritic growth on the surface of pristine Cu2Se thin films. The XRD spectra of the dendritic film identified the presence of CuCl2 and SeCl4 in addition to Cu2Se and this was also confirmed in the EDS analysis. The XPS results revealed that dendritic growth was CuCl2 while the residual base film was rich in elemental Se. Based on these results a reaction mechanism was proposed which involved the disproportionation and decomposition of copper selenide thin film under the influence of HCl vapour. In the present study, it was found that the highly mobile copper atoms diffused from the copper selenide matrix in the presence of HCl vapour, leading to the formation of CuCl2 dendritic structure leaving the residual base film rich in elemental Se along with traces of SeCl4.

Transparent, Conducting Self‐Assembled CuS Nanostructures at and beyond Liquid‐Liquid Interface and their Electrocatalytic Properties

AbstractThe liquid‐liquid interface (LLI) technique has been used to form thin films of various materials parallel to the interface. In this report, by taking CuS as an example, we show that CuS not only adopts thin film structures at the liquid‐liquid interface parallel to the interface but can also utilize beyond the interface to form self‐supported vertically aligned CuS thin films by controlling the precursor concentration. We also report the formation of a self‐assembled monolayer of CuS nanoparticles in the dichlorobenzene‐water interface at a lower concentration of copper. Thin films generated at LLI show p‐type conductivity with a sheet resistance of ∼350 Ω/□ and transparency up to 72 % at 550 nm. CuS also show electrocatalytic activity towards glucose sensing with a sensitivity of 3958 μA mM−1 cm−2, which is among the best in copper‐based materials.