Laser Deposition Technique Research Articles

Effect of laser parameters on the properties of high entropy alloys: A preliminary study

This preliminary study investigates the fabrication of Al-Co-Cr-Fe-Ni-Cu and Al-Ti-Cr-Fe-Co-Ni High Entropy Alloys with the Laser Deposition Technique. The effect of the laser parameters on the microstructure and hardness properties of the advanced materials were studied for aerospace applications. The results revealed that significant 300% increment occurs in the microhardness from 200 to 600 HV for the AlCoCrFeNiCu alloy system and 70% increment from 500 to 850 HV for the AlTiCrFeCoNi system as the laser power increases from 600 W to 800 W. However, as the scanning speed increases, the microhardness decreases. There were no notable changes in the microstructure interface of both alloys with a change in process parameters and further analysis showed the AlCoCrFeNiCu alloy had a transitional columnar dendritic structure while the AlTiCrFeCoNi alloy had the equiaxed dendritic microstructure with the direction of the grains observed along with the height of the deposit. The hardness properties of AlTiCrFeCoNi observed was attributed to the Ti content known to improve strength by facilitating a solid laves phase which suggests a potential application for aerospace wear-resistant coatings.

The structural and optical properties of mg-doped zinc oxide multiquantum barrier thin films

[Formula: see text]O asymmetric quantum barriers on JGS1 quartz glass and [Formula: see text] substrates were prepared by a pulsed laser deposition (PLD) technique. Microstructure characterization confirmed the designed structure. Because of the design of [Formula: see text] asymmetric quantum barrier, representative exciton peaks were observed in the optical absorption spectrum at room-temperature. This confirmed that the designed [Formula: see text] asymmetric quantum barrier structure realized the quantum-binding effect at room-temperature. Moreover, when [Formula: see text], the asymmetric quantum barrier structure had optimum performance compared with other [Formula: see text] values.

Improved growth conditions of pulsed laser-deposited PbI2 nanostructure film: towards high- photosensitivity PbI2/CNTs/Si photodetectors

Nanostructured PbI2 films were grown by laser deposition technique at a substrate temperature of 45 °C was demonstrated. Herein, we attempted to improve and control the crystal growth of PbI2 film and p-PbI2/MWCNTs/p-Si photodetector by finding the optimum laser fluence. X-ray diffraction XRD results illustrate that the grown PbI2 films are polycrystalline with hexagonal structure along (001) and the film crystallinity degraded with increasing the laser fluence. Scanning electron microscope SEM revealed that the particle size decreases as laser fluence increase and film deposited at 3.9 J/cm2 was dense and the grains distributed uniformly over the surface of the film. Energy dispersive X-ray EDX data confirms that the film stoichiometry depends on laser fluence and the film deposited at 3.9 J/cm2 was stoichiometric PbI2. The Photosensitivity investigations reveal that responsivity as high as 0.4 A/W at 610 nm was obtained for the p-PbI2/MWCNTs/p-Si photodetector prepared at 3.9 J/cm2 without post-deposition annealing.

Optical Properties of Mixed ZnO: Fe2O3 Grown via Pulsed laser deposition

In this study, mixing of zinc oxide (ZnO) nanoparticles with iron oxide(Fe2O3) at (0, 0.1, 0.3, 0.5 and 1)%wt., are deposited on glass substrates by pulsed laser deposition (PLD) technique for study characterization ZnO:Fe2O3 as solar cell electrode. The profound effect of mixed film on the structural and optical of ZnO: Fe2O3 thin films was observed. Meanwhile, the films have polycrystalline Hexagonal structures for ZnO, Rhombohedra and cubic structure for Fe2O3, and as indicated by the X-ray diffraction patterns of the films. The mean crystallite size of ZnO increase with increasing mixed ratio. The direct energy gap (Eg) of ZnO is 3.36 eV and decreasing with increasing mixed ratio.

Flower-like aluminium nitride nanostructures deposited by rf magnetron sputtering on superhard rhodium boride films

In this work, we demonstrate the feasibility to obtain aluminium nitride (AlN) nanostructures by radio frequency magnetron sputtering technique. In particular, nanostructured flower-like morphologies are achieved through a direct growth of AlN films on superhard rhodium boride (RhB) layers deposited by means of pulsed laser deposition (PLD) technique. AlN is deposited at different substrate temperatures in the range 300–500 °C in order to investigate the effects on morphology and crystalline structure. The samples are characterized by field emission scanning electron microscopy, atomic force microscopy, X-ray diffraction analysis and photoluminescence measurements. Results reveal nanostructured flower-like morphology of AlN for samples grown at different temperatures, while the smoothing of flower-petals with the increasing of temperature is observed. X-ray diffraction analysis indicate that the (002) crystallographic texture of the samples decreased upon the increase of the deposition temperature and only for the sample deposited at 300 °C a strong c-axis orientation is obtained.

Dynamically tuneable PLD grown SBN75 thin film based Electro optic modulator

Abstract:Present work reports the growth of Strontium Barium Niobate (Sr0.75 Ba0.25 Nb2 O6, SBN 75)thin films using Pulsed laser deposition (PLD) technique for possible realization of electrically tunable modulators. Structural and optical properties of grown SBN75 thin film were investigated indicating the growth of high quality polycrystalline and optically transparent. Prism coupling technique was further utilized for coupling the incident laser light λ = 633 nm with the grown SBN75 thin film. The guided EM radiation could be further coupled with the electric field for the realization of EO modulator.

Effect of lasing energy on the structure and optical and gas sensing properties of chromium oxide thin films

Chromium oxide (Cr2O3) thin films were prepared by the pulsed laser deposition (PLD) technique onto glass substrates using different laser pulse energies (500–900 mJ). The thickness of the prepared films ranged from 177.3 to 372.4 nm. The X-ray diffraction (XRD) study revealed that Cr2O3 thin films are amorphous, but they converted to the rhombohedral crystalline structure with space symmetry group after annealing at 300 °C for two hours. Furthermore, the atomic force microscopy (AFM) exhibited the formation of smooth and well-dispersed surfaces. The optical measurements in the wavelength range between 300 and 1100 nm confirmed that the optical energy gap of the prepared films decreased with increasing laser pulse energy, and a transition of the indirect type with a band gap of ≈ 3.90 eV was determined. The effect of the operation temperature on thin films’ sensitivity has been studied with the aim of optimizing the operation temperature as well as the response and recovery time for the prepared Cr2O3 thin films.

In vitro haemocompatibility and cytocompatibility evaluation of silver thin film-deposited heart valve prosthesis material

ABSTRACTOne of the most important requirements for a blood-interfacing implant like pyrolytic carbon (PyC)-based heart valve prosthesis is biocompatibility. The aim of this investigation was to evaluate the in vitro haemocompatibility and cytocompatibility of PyC surfaces coated with silver thin films by pulsed laser deposition (PLD) technique at various ablation pulses. The haemocompatibility of the coated PyC surfaces was assessed by the estimation of thrombin time (TT) and the percentage of haemolysis and analysis of platelet aggregation by scanning electron microscopy. The in vitro cytotoxicity of AgNP-coated PyCs at 7500 and 10,000 ablation pulses was tested against chick fibroblast and human peripheral blood mononuclear (PBM) cells by optical microscopy, methylthiazolyl diphenyl-tetrazoliumdiphenyl-tetrazolium bromide assay and epifluorescence microscopy. The results showed that the deposition of AgNPs on PyCs up to 10,000 ablation pulses had improved the haemocompatibility significantly when compared to uncoated controls which were evident from the increased TT, decreased haemolysis and little or no platelet aggregation. AgNP coating of PyCs prepared at both ablation pulses had significantly improved their cytocompatibility to fibroblast and PBM cells when compared to untreated controls. Deposition of AgNPs by PLD technique has converted the procoagulant nature of PyC material into anticoagulant one and also enhanced the cytocompatibility of the heart valve material.

Enhancement of Critical Current Density of Yttrium Barium Copper Oxide Thin Films by Introducing Nano dimensional Cerium Oxide Defects

The critical current density, Jc  has been the most important parameter used in the design and engineering of effective devices which is one of the implementation of high temperature superconductors (HTSC). In this work, an effort has been made to further improve the critical current density of YBa2Cu3O7-x (YBCO) thin films by preventing the magnetic flux line lattice against the Lorentz force by pinning it in place with the aid of nano-dimensional defects. These defects were generated by distributing nano sized CeO2 islands after YBCO layer was created on LaAlO3 substrates perpendicular to the film using pulsed laser deposition (PLD) technique. Three samples with buffer layers of CeO2 were prepared. CeO2 with 50 pulses, 100 pulses and 150 pulses, after each 1000 pulses of YBCO were prepared five layers for each of the samples. The structural characterization of YBCO/CeO2 and YBCO pristine films were carried out using x-ray diffraction (XRD) and scanning electron microscopy (SEM). Superconducting proprieties were measured using a vibrating sample magnetometer (VSM). Jc  for the pure YBCO and the YBCO/CeO2 films were calculated from magnetization (M) versus Field (H) loops using Bean’s model. Jc  for the 50 pulses of YBCO/CeO2 films was found to be increased slightly by an order of magnitude of about 40% with respect to those of YBCO films without the nano dimensional defects.

Development of Next‐Generation Organic‐Based Solar Cells: Studies on Dye‐Sensitized and Perovskite Solar Cells

AbstractNext‐generation organic solar cells such as dye‐sensitized solar cells (DSSCs) and perovskite solar cells (PSCs) are studied at the National Institute of Advanced Industrial Science and Technology (AIST), and their materials, electronic properties, and fabrication processes are investigated. To enhance the performance of DSSCs, the basic structure of an electron donor, π‐electron linker, and electron acceptor, i.e., D–π–A, is suggested. In addition, special organic dyes containing coumarin, carbazole, and triphenylamine electron donor groups are synthesized to find an effective dye structure that avoids charge recombination at electrode surfaces. Meanwhile, PSCs are manufactured using both a coating method and a laser deposition technique. The results of interfacial studies demonstrate that the level of the conduction band edge (CBE) of a compact TiO2 layer is shifted after TiCl4 treatment, which strongly affects the solar cell performance. Furthermore, a special laser deposition system is developed for the fabrication of the perovskite layers of PSCs, which facilitates the control over the deposition rate of methyl ammonium iodide used as their precursor.

XPS resolved surface states analysis of ZnO and Ni doped ZnO films for quantum well applications

ZnO and Ni doped ZnO (NiZnO) thin films were fabricated on c-plane sapphire substrate using Pulsed Laser Deposition (PLD) Technique. The surface states of the deposited thin films were analyzed using X-Ray Photoelectron spectroscopy (XPS) technique. The Zn LMM Auger transitions during XPS were examined in detail to identify the doping induced structural transformations in ZnO films. Hall effect and UV-Visible spectroscopic measurements were carried out on the prepared samples to estimate the electronic and optical properties. The obtained results favor the utilization of NiZnO as active well layer and ZnO as barrier layer in NiZnO/ZnO based Quantum Well structure fabrication.

Study of birefringence and electro-optic effect in SBN60 thin film

Recent advances towards Electro-optic (EO) modulators make use of the Pockel’s effect in non-centrosymmetric crystals which allows the efficient modulation of light beam. The large value of electro-optic (EO) coefficient of Strontium barium niobate has gained advances in field of electro optic devices. In the present work, field-induced birefringence was measured in the transverse geometry for 800 nm thin SBN film deposited using Pulsed Laser Deposition (PLD) technique on the fused silica substrate. A small birefringence was induced in the as-deposited film by the alignment of the incident laser along c-axis in the film plane and applying dc electric field perpendicular to it. The value of induced birefringence was found to vary with applied electric field in a non-linear manner indicating the presence of EO Pockel’s and a weak Kerr effect.

Pulsed laser deposited hexagonal wurzite ZnO thin-film nanostructures/nanotextures for nanophotonics applications

The high-quality and transparent thin-film zinc oxide (ZnO) nanostructures/nanotextures deposited on glass and silicon substrates using pulsed laser deposition (PLD) technique are reported. A solid-state, Nd-YAG laser was used for the PLD process. The films were deposited (i) at room temperature of 25°C (as deposited), (ii) at 150°C, (iii) at 300°C, (iv) at 450°C, and (v) at 600°C and annealed in the vacuum chamber. The depositions were also carried out at different laser repetition rates such as 10 and 5 Hz. UV spectroscopy and photoluminescence (PL) spectroscopy were carried out for optical studies. X-ray diffraction studies were carried out for all samples and analyzed the effects of the laser repetition rate, deposition, and annealing temperatures on the structural properties. Field-emission scanning electron microscope images are recorded for the best-structured samples. The electrical parameters were calibrated using the Hall effect measurement system and the IV characterization was performed using a CHI Electrochemical workstation. The deposition temperature has a significant effect on the microstrain and dislocation density of the ZnO thin film and optical phenomena with various electrical parameters, including the electron mobility, conductivity, and magnetoresistance. These promising results are suitable conditions for nanophotonics applications.

Structural and electrical transport properties of La2Mo2O9 thin films prepared by pulsed laser deposition

We have studied the structure and electrical properties of La2Mo2O9 thin films of different thicknesses prepared by the laser deposition technique at different substrate temperatures. The structural properties of the thin films have been investigated using XRD, XPS, AFM, TEM, SEM, and Raman spectroscopy. The electrical transport properties of the thin films have been investigated in wide temperature and frequency ranges. The cubic nature of the thin films has been confirmed from structural analysis. An enhancement of the oxygen ion conductivity of the films up to five orders of magnitude is obtained compared to that of the bulk La2Mo2O9, suggesting usefulness of the thin films as electrolytes in micro-solid oxide fuel cells. The enhanced dc ionic conductivity of the thin films has been interpreted using the rule of the mixture model, while a power law model has been used to investigate the frequency and temperature dependences of the conductivity. The analysis of the results predicts the three-dimensional oxygen ion conduction in the thin films.

Alternate current conductivity in BSb films prepared by PLD technique: Electron transport processes in low-temperature range (10-275 K)

This study is focused on the measurement of alternate current (a.c.) electrical conductivity of BSb films, deposited on fluorine-doped tin oxide (FTO)-coated glass substrates at 673K by the pulsed laser deposition (PLD) technique. The frequency-dependent a.c. conductivity is measured as a function of temperature (10-275K) and frequency (100Hz-100kHz). The transport processes governing the electrical conduction processes in this material are analyzed critically. It is observed from FESEM micrograph that the film is composed of small discrete grain with sizes varying in the range 6-12nm. It is interesting to notice from $ \ln\sigma_{\rm ac}$ versus 1000/T plot that there are three distinct zones: i) Semiconductor zone at high temperature from 275 to 150K, ii) Insulator zone at low temperature from 70 to 10K and iii) an abrupt change of the $ \ln\sigma_{\rm ac}$ versus 1000/T plot at ∼ 75 indicating MIS transition occurring in this BSb film. We found that the activation energy for the BSb films in the lower-temperature range was quite low ∼ 6 to 41neV, while that in the higher-temperature range was 20 to 50meV.

TiO2- CuI Nanoparticle /Ru Solid State Dye-Sensitize Solar Cells

In this work solid state dye sensitized solar cell (SSDSSC) type (ITO / TiO2/ Ru / CuI / Ag) is fabricated. The thin films are prepared by pulse laser deposition (PLD) technique under the vacuum pressure of 3×10−3 mbar and annelid at 450 oC. In this technique Nd:YAG laser at 1064 nm wavelength with (200 , 500 , 800) pulsed was used. It was noticed from (I-V) characteristics of the solar cell that the photocurrent collected from the TiO2 (NP) is increase as the number of laser pulses increase. The conversion efficiency of TiO2 is increased from 2.115% up to 5.654% and for CuI from 1.73 % to 5.19 % when the number of pulses increase from 200 up to 800.

Epitaxial thin-film growth of Ruddlesden–Popper-type Ba3Zr2O7 from a BaZrO3 target by pulsed laser deposition

Ruddlesden–Popper Ba3Zr2O7 thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba3Zr2O7 phase from BaZrO3 target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba3Zr2O7 thin films were annealed at 500, 600 and 800 °C. X-ray diffraction (XRD) reveals the formation of Ba3Zr2O7 phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 °C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba3Zr2O7 Ruddlesden–Popper-type perovskite structure.

ANGULAR DISTRIBUTION OF TUNGSTEN MATERIAL AND ION FLUX DURING NANOSECOND PULSED LASER DEPOSITION

Tungsten thin films were prepared by pulsed laser deposition (PLD) technique on glass substrates placed at the angles of 0[Formula: see text] to 70[Formula: see text] with respect to the target surface normal. Rutherford backscattering Spectrometry (RBS) analysis of the films indicated that about 90% of tungsten material flux is distributed in a cone of 40[Formula: see text] solid angle while about 54% of it lies even in a narrower cone of 10[Formula: see text] solid angle. Significant diffusion of tungsten in glass substrate has been observed in the films deposited at smaller angles with respect to target surface normal. Time-of-flight (TOF) measurements performed using Langmuir probe indicated that the most probable ion energy decreases from about 600 to 91[Formula: see text]eV for variation of [Formula: see text] from 0[Formula: see text] to 70[Formula: see text]. In general ion energy spread is quite large at all angles investigated here. The enhanced tungsten diffusion in glass substrate observed at smaller angles is most probably due to the higher ion energy and ion assisted recoil implantation of already deposited tungsten.

Pulsed laser deposition of silver nanoparticles on prosthetic heart valve material to prevent bacterial infection

Pyrolytic carbon (PyC) is a biomaterial widely employed as artificial heart valve but prone to bacterial infections like endocarditis. The aim of this investigation was to prevent bacterial colonisation by coating the surface of PyC with a thin film of silver nanoparticles (AgNPs) using pulsed laser deposition (PLD) technique. Thin films were deposited at 5000, 7500, 10,000, 12,500 and 15,000 ablation pulses and characterised by surface profilometer, scanning electron microscopy, energy dispersive X-ray analysis and atomic force microscopy. The antibacterial activity of AgNPs films was evaluated against gram-positive and gram-negative bacteria including methicillin resistant Staphylococcus aureus (MRSA) by the zone of inhibition method. The mean particle sizes of all AgNPs were below 30 nm and the film thickness, roughness and particle size increased with the increase in number of ablation pulses. All films of AgNPs showed significant antibacterial effect against all tested pathogens except that films prepared at 12,500 pulses alone had antibacterial activity against MRSA. The AgNPs coating had led to the betterment of haemocompatibility of PyC especially at 7500 and 10,000 ablation pulses. Film roughness as well as AgNPs’ particle size which are in nano range can be attributed to the inhibition of bacterial growth. The coating of AgNPs thin films on PyC samples using PLD technique had improved haemocompatibility properties and potential to prevent bacterial attack of the biomaterial surface.

Photovoltaic characteristics of boron doped amorphous carbon films deposited by pulsed laser deposition using graphite target

This paper reports on the successful deposition of boron (B) doped carbon films (p-C(B)) and fabrication of p-C(B)/n-Si solar cells by pulsed laser deposition (PLD) technique at room temperature using graphite target. The B content in the film was determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.2-1.7 atomic percentage. The photovoltaic values of the device, a maximum open circuit voltage, V oc = 250 m V and short circuit current density, J sc = 2.113 mA/cm 2 were obtained, when exposed to AM 1.5 illumination (100 mW/cm 2 , 25°C). The maximum energy conversion efficiency was found tentatively to be about, η = 0.2%, together with the fill factor, FF = 45%. In this paper, the dependence of the B content on electrical and optical properties of the p-C(B) films and the photovoltaic characteristic of the p-C(B)/n-Si structure photovoltaic solar cells are discussed.