Argon Target Research Articles

Compositional Optimization of Sputtered SnO2/ZnO Films for High Coloration Efficiency

We performed an electrochromic investigation to optimize the composition of reactive magnetron-sputtered mixed layers of zinc oxide and tin oxide (ZnO-SnO2). Deposition experiments were conducted as a combinatorial material synthesis approach. The binary system for the samples of SnO2-ZnO represented the full composition range. The coloration efficiency (CE) was determined for the mixed oxide films with the simultaneous measurement of layer transmittance, in a conventional three-electrode configuration, and an electric current was applied by using organic propylene carbonate electrolyte cells. The optical parameters and composition were measured and mapped by using spectroscopic ellipsometry (SE). Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) measurements were carried out to check the SE results, for (TiO2-SnO2). Pure metal targets were placed separately from each other, and the indium–tin-oxide (ITO)-covered glass samples and Si-probes on a glass holder were moved under the two separated targets (Zn and Sn) in a reactive argon–oxygen (Ar-O2) gas mixture. This combinatorial process ensured that all the compositions (from 0 to 100%) were achieved in the same sputtering chamber after one sputtering preparation cycle. The CE data evaluated from the electro-optical measurements plotted against the composition displayed a characteristic maximum at around 29% ZnO. The accuracy of our combinatorial approach was 5%.

Measurement of the absolute efficiency of the X-ARAPUCA photon detector for the DUNE Far Detector 1

The DUNE far detector has been designed to detect photons and electrons generated by the charged products of the interaction of neutrinos with a massive liquid argon (LAr) target. The photon detection system (PDS) of the first DUNE far detector (FD1) is composed of 6000 photon detection units, named X-ARAPUCA. The detection of the prompt light pulse generated by the particle energy release in LAr will complement and boost the DUNE LAr Time Projection Chamber. It will improve the non-beam events tagging and enable at low energies the trigger and the calorimetry of the supernova neutrinos. The X-ARAPUCA is an assembly of several components. Its photon detection efficiency (PDE) depends on the design of the assembly, on the grade of the individual components and on their coupling. The X-ARAPUCA PDE is one of the leading parameters for the PDS sensitivity, that in turn determines the sensitivity of the DUNE for the detection of core-collapse supernova within the galaxy and for nucleon decay searches. In this work we present the final assessment of the absolute PDE of the FD1 X-ARAPUCA baseline design, measured in two laboratories with independent methods and setups. Preliminary results were reported in Palomares (JINST 18(02):C02064, https://doi.org/10.1088/1748-0221/18/02/C02064, 2023). One hundred sixty units of these X-ARAPUCA devices have been deployed in the NP04 facility at the CERN Neutrino Platform, the 1:20 scale FD1 prototype, and will be operated during the year 2024. The assessed value of the PDE is a key parameter both in the NP04 and in the DUNE analysis and reconstruction studies.

Resolving studies of Balmer alpha lines relevant to the LIBS analysis of hydrogen isotope retention

Utilizing Laser-Induced Breakdown Spectroscopy (LIBS) for detecting deuterium and tritium retention in fusion devices poses a significant challenge due to the experimental limitations in resolving hydrogen isotope Balmer alpha lines (Hα, Dα, and Tα). This study utilizes the Rayleigh criterion to distinguish Tα and Dα lines by determining the maximum line widths and corresponding plasma parameters. Experimental validation was performed through LIBS analysis of heavy water-doped graphite/silica gel targets in both argon and helium atmospheres to assess the predicted plasma parameters and line profile shapes. The optimization of laser pulse energy, gas pressure, delay, and gate times aimed at achieving fully resolved lines based on the intensity, width, and the dip between deuterium and hydrogen Balmer alpha lines. By fine-tuning these experimental parameters, the study successfully achieved a dip of less than 10 % between the Hα and Dα lines with a satisfactory signal-to-noise ratio, demonstrating the feasibility of fully resolving the Tα and Dα lines. These findings underscore the potential of LIBS in enhancing the detection of deuterium and tritium retention in fusion devices.

Imaging systems for the liquid Argon target of SAND at the DUNE Near Detector Complex

The Deep Underground Neutrino Experiment (DUNE) has among its primary goals the determination of the neutrino mass ordering and the possible CP-violating phase in the neutrino mixing matrix. The System for On-Axis Neutrino Detection (SAND) is one of the three components of the DUNE Near Detector complex, permanently located on-axis to monitor the neutrino beam stability and measure its flux. SAND includes a novel liquid Argon detector - GRAIN - designed to image neutrino interactions using scintillation light produced in Ar by charged particles, eliminating the dependence on slow charge collection of LAr TPCs. Two optical systems are currently being developed for GRAIN, both based on Silicon Photomultiplier (SiPM) matrices, coupled either to UV cryogenic lenses or Coded Aperture masks. This contribution will present the design of GRAIN optical systems and their spatial resolution performance in preliminary simulation studies.

Magnetron carbon structures obtained by high-frequency magnetron sputtering in Argon and Nitrogen

Purpose of research. Creation and characterization of carbon nanostructures by high-frequency magnetron sputtering from a carbon target in argon on a silicon substrate and in a reactive nitrogen environment, obtained on a Ni catalyst buffer layer. Methods. High-frequency magnetron sputtering on a silicon substrate with changes in control parameters: sputtering time power and working gas pressure Ar and N. Research was carried out using X-ray phase analysis, atomic force microscopy and holographic microscopy, Raman scattering. Results. The formation of carbon nanotubes, including single-walled ones, was confirmed by the method of Raman scattering of light along the lines ID 1363 and IG 1564 cm-1, as well as ωRDМ 308 and 227 cm–1. Using atomic force microscopic images, the fractal dimension of the nanofilms was calculated, which indicated their 3D nature. Based on X-ray phase analysis of magnetron nanofilms, the dimensions of the coherence region, texture, microdeformations and interplanar deformation distortions were determined. Conclusion. In carbon magnetron nanofilms, deformations of both signs occur: both compressive (∆a < 0) and tensile (∆a > 0). Carbon magnetron nanofilms are represented, among other things, by single-walled carbon nanotubes, the chirality of which in an argon environment is (6, 6), and in a reactive mixture of nitrogen and argon on a Ni buffer layer (7, 7). It was discovered that in high-frequency magnetron mode, silicon carbide is formed in both inert and reactive environments.

Comparative study of RF sputtered Fe2O3- and Fe3O4-doped indium saving indium tin oxide thin films

In present work the properties of iron-doped indium tin oxide (ITO) films with reduced to 50 mass% indium oxide content prepared by co-sputtering of ITO and Fe2O3 targets and ITO and Fe3O4 targets in mixed argon–oxygen atmosphere were studied by various methods. The influence of different working gas flow rates, RF power of iron oxide targets, type of doping oxide and heat treatment temperatures on the electrical, optical, structural, and morphological properties of the films was characterized by means of four-point probe method, ultraviolet–visible (UV–Vis) spectroscopy, X-ray diffraction and atomic force microscopy.

Investigation of carrier transport in ZnO and ZnO:Al thin films sputtered at different oxygen conditions

Undoped and doped zinc oxide in film form is used in a wide range of applications. Its electrical and optical properties depend on the oxide conditions during preparation, which are influenced by many deposition parameters. The aim of this work was to experimentally investigate the properties of films deposited under clearly defined oxygen-rich and oxygen-poor conditions. The observed property changes were then described based on theoretical assumptions about internal defects formed in ZnO under different oxygen conditions. To achieve the objective, the ZnO and ZnO:Al films were sputtered in a mixture of argon and oxygen to ensure oxygen-rich conditions. Oxygen-poor conditions were provided by co-sputtering from oxide and metal targets in argon. We have found that the growth in oxygen-rich conditions leads to approximately stoichiometric ZnO films and the films prepared under oxygen-poor conditions are strongly oxygen deficient. The resistivity of undoped ZnO films can be controlled from 108 to 10−2 Ωcm while maintaining high transparency in the visible spectrum. The high resistivity is caused by the formation of deep acceptors under oxygen-rich conditions. The high concentration of zinc interstitials is responsible for the low resistivity in oxygen poor conditions. Even in the case of ZnO:Al films, the carrier concentration is strongly reduced at oxygen-rich conditions by the deep acceptors. These defects tend to relax during vacuum annealing at 300 °C due to self-diffusion. The carrier mobility is mainly related to the crystallinity. The formation of a high number of basal edge dislocations has been identified as a reason for the reduction in transmittance.

Evidence of 1000 eV positive oxygen ion flux generated in reactive HiPIMS plasma

The arrival of highly energetic (near 1000 eV) positive atomic oxygen ions at the substrate region has been detected in a unipolar reactive high-power impulse magnetron sputtering process operated with an uncooled copper target in argon–oxygen mixtures. Examination of the ion fluxes from discharge plasma was performed with a magnetic sector mass-spectrometer and an electrostatic energy analyzer. The energy of fast positive O+ ions is close to the value of eV d (e—elementary charge, V d—discharge voltage), which indicates their connection to the well-studied fraction of negative O− ions, which undergo acceleration in the cathode sheath. After switching the oxygen gas supply off, the flux of energetic O+ species decreases gradually as the poisoned target surface layers become depleted of oxygen due to sputtering in pure argon. Presumably, the observed energetic O+ ions originate as a result of low-angle scattering of fast negative O− ions from other charged or neutral species in the plasma followed by electron detachment, ionization, or charge exchange.

Search for low-mass dark matter WIMPs with 12 ton-day exposure of DarkSide-50

We report on the search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 10 GeV/c2, from the analysis of the entire dataset acquired with a low-radioactivity argon target by the DarkSide-50 experiment at Laboratori Nazionali del Gran Sasso. The new analysis benefits from more accurate calibration of the detector response, improved background model, and better determination of systematic uncertainties, allowing us to accurately model the background rate and spectra down to 0.06 keVer. A 90% C.L. exclusion limit for the spin-independent cross section of 3 GeV/c2 mass WIMP on nucleons is set at 6×10−43 cm2, about a factor 10 better than the previous DarkSide-50 limit. This analysis extends the exclusion region for spin-independent dark matter interactions below the current experimental constraints in the [1.2, 3.6] GeV/c2 WIMP mass range.5 MoreReceived 28 July 2022Accepted 6 January 2023DOI:https://doi.org/10.1103/PhysRevD.107.063001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDark matterParticle dark matterPhysical SystemsWeakly interacting massive particlesTechniquesDark matter detectorsParticle detectorsParticles & FieldsNuclear PhysicsGravitation, Cosmology & Astrophysics

Partial-wave representation of the strong-field approximation. II. Coulomb asymmetry in the photoelectron angular distribution of many-electron atoms

Strong-field ionization experiments are routinely performed with different atomic targets. While these experiments helped reveal many details about the light-matter interaction in intense laser fields, the target atoms are often modeled in a rather crude manner by neglecting most of their electronic structure. Until the present, therefore, many above-threshold ionization measurements had been understood only qualitatively, and this especially applies to the ionization with elliptically polarized laser pulses, for which the photoelectron angular distributions are known to exhibit a quite strong (Coulomb) asymmetry. This asymmetry arises from the Coulomb and short-range forces between the photoion and the outgoing field-dressed electron in the continuum. We demonstrate here how the strong-field approximation (SFA) can be combined with atomic structure theory for modeling such target-resolved observations. Using a partial-wave representation of the SFA, we show that this combination reproduces the Coulomb asymmetry for argon and xenon targets in good agreement with previous experiments and especially if a distorted-wave Volkov continuum is applied for the active electron. We therefore conclude that a better account of the initial and final electron waves in strong-field theories will enhance our understanding of ionization phenomena in intense fields.

Preparation and Structural Investigation of Ultra-Uniform Mo Films on a Si/SiO2 Wafer by the Direct-Current Magnetron Sputtering Method

As a kind of important strategic resource, molybdenum (Mo) and its alloys are widely applied in solar cells and 5G radio frequency filters. In order to improve the yield of industrial production, it is important to reduce the nonuniformity of thin-film thickness. We prepared Mo films on CMOS compatible Si/SiO2 wafers through a magnetron sputtering method and systematically investigated the effect of tuning of several process parameters on film thickness nonuniformity and other structural properties, including crystallite size (D), microstrain (ε), and dislocation density (δ). At optimized sputtering power (80 W), chamber pressure (0.4 Pa), argon flow rate (90 sccm), substrate temperature (350 °C), and target–substrate distance (9 cm), the deposited 200 nm-thick Mo films show a unified <110> preferred orientation, and the film thickness nonuniformity reaches an excellent value of 0.46%, with a surface roughness of 0.83 nm and the full width at half maximum (FWHM) of X-ray diffraction (XRD) (110) rocking curve as low as 0.47°. Our results provide efficient reference for the preparation of uniform metal films, which have potential for improving the quality and yield in filter device manufacturing.

Two-dimensional axisymmetric radiation hydrodynamics model of moderate-intensity nanosecond laser-produced plasmas

A two-dimensional axisymmetric radiation hydrodynamics model has been proposed to simulate nanosecond laser ablation of a solid target in ambient argon, air and helium at different pressures. The heat conduction equation used to simulate the conduction of laser deposition energy in the target and gas dynamic equations to describe the interaction between laser and vapor plasma and the evolution of plasma are coupled through the Knudsen layer relations at the target-vapor interface. A collisional-radiative model including 12 atomic processes is used to calculate the population of atomic energy levels and fractional ion abundance. The internal energy and pressure of the plasma are expressed by the equations of state based on a real gas approximation, which divides the internal energy into the ionization energy, thermal energy, and excitation energy of atoms and ions. The distributions of the temperature, pressure, density and velocity of the target and plasma are calculated by using this model, and the results are analyzed. Experimental results of multiple diagnostic tools including fast photography, shadowgraphy images, spatio-temporally resolved optical emission spectroscopy and laser interferometry, are used to benchmark the simulation results, and satisfactory consistencies are obtained. The model provides a numerical tool to interpret experimental data of a moderate-intensity nanosecond laser ablated solid target when the temperature of the target surface does not reach the critical value.

Equivalent circuits of FeCoZr-alloy nanoparticles deposited into Al2O3 and PZT dielectric matrices nanogranular composite films

The paper presents equivalent substitution circuits (ESCs) describing nanogranular composite films (Fe0.45Cо0.45Zr0.10)x(Al2O3)1 – x and (Fe0.45Cо0.45Zr0.10)x(PZT)1 – x with a concentration of metal-containing granules in the range 0.3 &lt; х &lt; 0.8. Films of 2–7 μm thick were obtained by ion-beam sputtering of composite targets in pure argon or in Ar – O2 mixture, followed by stepwise (with a step of 25 K) isochronous (15 min) annealing in air in the temperature range of 398 – 873 K. Deposition of nanocomposites in an oxygen-containing atmosphere or subsequent annealing in air led to the formation of nanoparticles with a core – shell structure consisting of Fe0.45Cо0.45Zr0.10 metallic alloy cores coated with shells of native iron and cobalt oxides (FeO, Fe3O4, Fe2O3, CoO). It has been established that when such shells contain semiconductor-type iron oxides (like FeO and Fe3O4) the frequency dependences of the total impedance Z (f, T) of nanocomposites can be described using ESCs containing two resonant RCL-circuits, that is accompanied by a positive phase shift of the current relative to the applied bias voltage (the so-called negative capacitance effect). The prevailing of dielectric-like oxides (Fe2O3) in shells around metallic cores leads to ESCs either with one resonant RCL-circuit or without it at all. This results in disappearing of the negative capacitance effect when usual capacitive-like behaviour of nanocomposite behaviour is observed. It is shown that if we construct ESCs for nanocomposites with different ratios of the metallic (FeCoZr) and dielectric (Al2O3, PZT) components, it is possible to describe the Z (f, T) dependences for every circuit elements (R, C, L) corresponding both to individual phase components in nanocomposites including intrinsic semiconductor- or dielectric-like iron and cobalt oxides in shells around metallic cores.

First direct limit on the 334 keV resonance strength in ^{22}Ne(alpha ,gamma )^{26}Mg reaction

In stars, the fusion of ^{22}Ne and ^4He may produce either ^{25}Mg, with the emission of a neutron, or ^{26}Mg and a gamma ray. At high temperature, the (alpha ,n) channel dominates, while at low temperature, it is energetically hampered. The rate of its competitor, the ^{22}Ne(alpha ,gamma )^{26}Mg reaction, and, hence, the minimum temperature for the (alpha ,n) dominance, are controlled by many nuclear resonances. The strengths of these resonances have hitherto been studied only indirectly. The present work aims to directly measure the total strength of the resonance at E_{text {r}} = 334 keV (corresponding to E_{text {x}} = 10949 keV in ^{26}Mg). The data reported here have been obtained using high intensity ^4He^+ beam from the INFN LUNA 400 kV underground accelerator, a windowless, recirculating, 99.9% isotopically enriched ^{22}Ne gas target, and a 4pi bismuth germanate summing gamma -ray detector. The ultra-low background rate of less than 0.5 counts/day was determined using 63 days of no-beam data and 7 days of ^4He^+ beam on an inert argon target. The new high-sensitivity setup allowed to determine the first direct upper limit of 4.0,times ,10^{-11} eV (at 90% confidence level) for the resonance strength. Finally, the sensitivity of this setup paves the way to study further ^{22}Ne(alpha ,gamma )^{26}Mg resonances at higher energy.

A substandard candle: the low-nu method at few-GeV neutrino energies

As accelerator-based neutrino oscillation experiments improve oscillation parameter constraints with more data, control over systematic uncertainties on the incoming neutrino flux and interaction models is increasingly important. The intense beams offered by modern experiments permit a variety of options to constrain the flux using in situ “standard candle” measurements. These standard candles must use very well understood interaction processes to avoid introducing additional interaction model dependence. One option often discussed in this context is the “low-nu ” method, which is designed to isolate neutrino interactions where there is low energy-transfer to the nucleus, such that the interaction cross section is expected to be approximately constant as a function of neutrino energy. The shape of the low-energy transfer event sample can then be used to extract the flux shape. Applications of the method at high neutrino energies (many tens of GeV) are well understood. However, the applicability of the method at the lower energies of current and future few-GeV accelerator neutrino experiments remains unclear due to the presence of nuclear and form-factor effects inherent in the interaction models.In this analysis we examine the prospects for improving constraints on the accelerator neutrino fluxes in situ with the low-nu method in an experiment-independent way, using (anti)neutrino interactions on argon and hydrocarbon targets from the GENIE, NEUT, NuWro and GiBUU event generators. We begin by investigating the extent to which deviations from the constant cross-section assumption are dependent on poorly understood aspects of the neutrino interaction model. We then assess whether a low energy-transfer event sample can be confidently identified using experimentally accessible observables. We finally consider how the practicalities of reconstructing the energy spectrum of interacting neutrinos in realistic detectors might further limit the utility of low-nu flux constraints. The results show that flux constraints from the low-nu method would be severely dependent on the interaction model assumptions used in an analysis of neutrinos with energies below 5 GeV, and anti-neutrinos below at least 15 GeV. The spread of model predictions show that a low-nu analysis is unlikely to offer much improvement on typical neutrino flux uncertainties, even with a perfect detector. Notably—running counter to the assumption inherent to the low-nu method—the model-dependence increases with decreasing energy transfer for experiments in the few-GeV region.

On thermal stability and oxidation behavior of metastable W–Zr thin-film alloys

The thermal stability and oxidation behavior of metastable W–Zr thin-film alloys with up to 83 at.% Zr were thoroughly investigated with a focus on the effect of gradual substitution of Zr for W. The films were prepared by dc magnetron co-sputtering of W and Zr targets in argon on unheated and unbiased substrates. The experiments showed that a supersaturated α-W(Zr) solid solution structure of as-deposited W-rich films with up to 19 at.% Zr is highly thermally stable up to 1200 °C in argon and the thermal stability of the W–Zr thin-film metallic glasses (33–83 at.% Zr) decreases with increasing Zr content. Nevertheless, the thermal stability of the W–Zr thin-film metallic glass with 33 at.% Zr reaches 1420 °C, which is very high value for binary metallic glass. The annealing of W-rich films (0–24 at.% Zr) in air leads to the formation of a protective surface oxide layer, which serves as a more effective oxygen diffusion barrier due to an increasing packing factor and amorphization with Zr addition. On the other hand, no protective surface oxide layer is grown during the annealing in air in the case of the W–Zr thin-film metallic glasses and the oxidation leads to the formation of compact, homogeneously oxidized substoichiometric W–Zr–O films with an amorphous structure and enhanced mechanical properties before reaching the final mass gain.

Determination of the argon spectral function from(e,e′p)data

The E12-14-012 experiment, performed in Jefferson Lab Hall A, has measured the $(e, e'p)$ cross section in parallel kinematics using a natural argon target. Here, we report the full results of the analysis of the data set corresponding to beam energy 2.222 GeV, and spanning the missing momentum and missing energy range $15 \lesssim p_m \lesssim 300$ MeV/c and $12 \lesssim E_m \lesssim 80$ MeV. The reduced cross section, determined as a function of $p_m$ and $E_m$ with $\approx$4\% accuracy, has been fitted using the results of Monte Carlo simulations involving a model spectral function and including the effects of final state interactions. The overall agreement between data and simulations turns out to be quite satisfactory ($\chi^2$/n.d.o.f.=1.9). The resulting spectral function will provide valuable new information, needed for the interpretation of neutrino interactions in liquid argon detectors.

Effects of racetrack magnetic field strength on structure and properties of amorphous carbon coatings deposited by HiPIMS using deep oscillation pulses

In this study, non‑hydrogenated diamond like carbon (DLC) coatings were deposited by sputtering a graphite target in argon (Ar) by high power impulse magnetron sputtering (HiPIMS) using deep oscillation pulses. The effects of the magnetic field strength (B) tangential to surface of the target racetrack on the deposition parameters were studied. The structure, adhesion, and mechanical properties of DLC coatings deposited at different B were investigated by scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), scratch test, and nanoindentation. The tribological properties of the DLC coatings were evaluated using ball on disk wear test under dry and lubricated test conditions. It was found that the peak target current and substrate current density increased as B increased due to the enhanced electron confinement which results in an increased ionization efficiency. The enhanced ion bombardment was beneficial for improving the structure and properties of DLC coatings. As B increased, the DLC coatings exhibited more compact structure, smaller carbon mounds, and higher sp3 bond fractions. The improvement of the microstructure of the DLC coatings contributed to improved hardness and wear resistance of the coatings in both dry and lubricated test conditions. However, the deposition rate decreased at higher B owing to the high probability of back-attraction of carbon ions. The results suggested that controlling B in the range of 600 G to 700 G is important for achieving fully dense structure, high sp3 bond fractions, and high hardness for the DLC coatings deposited using HiPIMS. A further increase in B to 850 G showed no significant changes in the magnetic field induced effects on the structure and properties of the coatings.

Uncertainties Due to Hadronic Production in Final-State Interactions at Long-Baseline Neutrino Facility

Recent neutrino oscillation experiments used high atomic number nuclear targets to attain sufficient interaction rates. The use of these complex targets introduced systematic uncertainties due to the nuclear effects in the experimental observables and need to be measured properly to pin down the discovery. Through this simulation work, we are trying to quantify the nuclear effects in the argon (Ar) target in comparison to hydrogen (H) target which are proposed to be used at Deep Underground Neutrino Experiment far detector and near detector, respectively. Generated Events for Neutrino Interaction Experiments and NuWro, two neutrino event generators, are used to construct final state kinematics. To quantify the systematic uncertainties in the observables, we present the ratio of the oscillation probabilities (P(Ar)/P(H)) as a function of the reconstructed neutrino energy.

Structural, optical and electrical properties of CuO nanostructures prepared by reactive DC magnetron sputtering

An attempt is made to explore the CuO nanostructures and their attributes in this work. CuO nanostructures are deposited on glass substrates using DC reactive magnetron sputtering using Cu target in argon (84%) and oxygen (16%) environment. These nanostructures are deposited at sputtering power of 70 W, different sputtering pressures in the range 1.0–8.0 Pa and deposition time of 10–60 min. X-ray diffraction (XRD) technique is used to determine the oxide phase of the deposited nanostructures. The XRD pattern matches CuO standard diffraction data (ICDD file 00-005-0661), confirming that no additional oxide phases appeared in the nanostructure coated for different deposition time at higher pressure. Due to the very low content of CuO, no peaks attributable to CuO are observed in the nanostructures deposited for 10 min at sputtering pressure of 3.0–8.0 Pa. In the nanostructure deposited at 1.0 Pa, a new phase Cu2O has evolved. The nanostructure deposited for 60 min has a crystallite size of 26 nm. Field emission scanning electron microscopy (FESEM) is used to analyse the morphologies of the nanostructures. Isolated nanograins of CuO are observed in nanostructures that have been deposited for 10 min, when the deposition time is extended to 40 and 60 min, an almost film-like structure is formed. Sputtering pressure of 8.0 Pa produces highly isolated nanograins; lowering the pressure results in less isolated nanograins. UV–Visible absorption spectroscopy is utilized for optical studies. Transmittance and absorbance spectra are recorded in the 200–1100 nm wavelength range. The nanostructures absorb light strongly in the 280–400 nm region and it is observed that decrease in the sputtering pressure (from 8.0 Pa to 1.0 Pa) and higher deposition time enhance the absorption capacity in this range (280–400 nm) as well as in the visible range. The nanostructures have transmittance of more than 80% in the wavelength range 780–1100 nm. The sheet resistance of the nanostructures is estimated to be between 10.3 and 25.0 kΩ/sq. Hall measurement confirms p-type conductivity of CuO nanostructures and carrier concentration reaches the order of 1018 cm−3.