Advantages Of Pulsed Laser Deposition Research Articles

Thin Films Fabricated by Pulsed Laser Deposition for Electrocatalysis

Thin Films Fabricated by Pulsed Laser Deposition for Electrocatalysis

Largest possible deviations from stoichiometry transfer during pulsed laser deposition

One of the major advantages of pulsed laser deposition (PLD) is the ability to transfer complex multicomponent materials stoichiometrically from a target to the growing film on a substrate. Nevertheless, in some systems small deviations from stoichiometry were found. In this paper, we show that it is possible to grow homogeneous alloy films with concentrations over an unprecedented large range of 0–97 wt% W from a single W80Cu20 target by just varying the laser fluence and additionally tilting the substrate during deposition. This is probably the largest deviation from stoichiometry transfer possible in a binary system.

Pulsed laser deposition of a dense and uniform Au nanoparticles layer for surface plasmon enhanced efficiency hybrid solar cells

A highly dense and uniform layer of Au nanoparticles (NPs) on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film has been produced by the pulsed laser deposition (PLD) technique toward the production of an improved efficiency photovoltaic device. The advantage of PLD over other techniques is the easy and precise control of the Au NPs size and spatial distribution, without needing of further NP surface functionalization. The efficiency enhancement factor related to Au NPs doping has been evaluated in a solar cell based on poly-(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) diffused bilayer. The short-circuit current density, J SC, increases by 18 % and the power conversion efficiency by 22 %, respectively, in comparison with an equivalent device without Au NPs. The optical and morphological properties of the Au NPs layer have been selected in order to evaluate the contribution of the surface plasmon resonance as enhancement factor of the solar cell efficiency, in a range size where light scattering is negligible.

Matrix shaped pulsed laser deposition: New approach to large area and homogeneous deposition

Pulsed laser deposition (PLD) is one of the well-established physical vapor deposition methods used for synthesis of ultra-thin layers. Especially PLD is suitable for the preparation of thin films of complex alloys and ceramics where the conservation of the stoichiometry is critical. Beside several advantages of PLD, inhomogeneity in thickness limits use of PLD in some applications. There are several approaches such as rotation of the substrate or scanning of the laser beam over the target to achieve homogenous layers. On the other hand movement and transition create further complexity in process parameters. Here we present a new approach which we call Matrix Shaped PLD to control the thickness and homogeneity of deposited layers precisely. This new approach is based on shaping of the incoming laser beam by a microlens array and a Fourier lens. The beam is split into much smaller multi-beam array over the target and this leads to a homogenous plasma formation. The uniform intensity distribution over the target yields a very uniform deposit on the substrate. This approach is used to deposit carbide and oxide thin films for biomedical applications. As a case study coating of a stent which has a complex geometry is presented briefly.

Brush-Shaped ZnO Heteronanorods Synthesized Using Thermal-Assisted Pulsed Laser Deposition

Brush-shaped ZnO heteronanostructures were synthesized using a newly designed thermal-assisted pulsed laser deposition (T-PLD) system that combines the advantages of pulsed laser deposition (PLD) and a hot furnace system. Branched ZnO nanostructures were successfully grown onto CVD-grown backbone nanowires by T-PLD. Although ZnO growth at 300 °C resulted in core-shell structures, brush-shaped hierarchical nanostructures were formed at 500-600 °C. Materials properties were studied via photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations. The enhanced photocurrent of a SnO(2)-ZnO heterostructures device by irradiation with 365 nm wavelength ultraviolet (UV) light was also investigated by the current-voltage characteristics.

Tribological properties of diamond-like carbon films deposited by pulsed laser arc deposition

A novel method, pulsed laser arc deposition combining the advantages of pulsed laser deposition and cathode vacuum arc techniques, was used to deposit the diamond-like carbon (DLC) nanofilms with different thicknesses. Spectroscopic ellipsometer, Auger electron spectroscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and multi-functional friction and wear tester were employed to investigate the physical and tribological properties of the deposited films. The results show that the deposited films are amorphous and the sp2, sp3 and C-O bonds at the top surface of the films are identified. The Raman peak intensity and surface roughness increase with increasing film thickness. Friction coefficients are about 0.1, 0.15, 0.18, when the film thicknesses are in the range of 17-21 nm, 30-57 nm, 67-123 nm, respectively. This is attributed to the united effects of substrate and surface roughness. The wear mechanism of DLC films is mainly abrasive wear when film thickness is in the range of 17-41 nm, while it transforms to abrasive and adhesive wear, when the film thickness lies between 72 and 123 nm.

Thermoelectric properties of Bi2Te3 based thin films fabricated by pulsed laser deposition

AbstractBi2Te3-based thin films were fabricated on glass substrates by the pulsed laser deposition (PLD) method. The vapor pressures of Bi and Te are significantly different, so controlling the stoichiometric composition is difficult when using conventional physical vapor deposition techniques, and the thermoelectric properties of Bi2Te3 films are sensitive to the film composition. PLD is a promising technique for the fabrication of telluride-based films such as Bi2Te3 due to its superior capability for controlling the film composition. Another advantage of PLD is the flexibility that it allows in terms of atmosphere in the reaction chamber; high concentrations of gases such as oxygen or argon can be introduced. We have measured various compositions of Bi2Te3 based films, and have identified the optimal compositions for both n-type and p-type material. The thermal conductivities of these Bi2Te3 films were evaluated by an exact measuring system, and the results were twice as low as those of conventional bulk materials. These results suggest that PLD has significant advantages for the deposition of in-plane Bi2Te3-based thin films.

Pulsed laser deposition of hard magnetic films

Pulsed laser deposition from elemental targets was used to prepare highly textured hard magnetic Nd–Fe–B and Fe–Pt films with coercivities of 2 T and 5.2 T, respectively. In situ methods such as reflection high energy electron diffraction and Auger electron spectroscopy were applied to analyse film composition and structure during growth. Optimisation of the hard magnetic properties is discussed together with the specific advantages of pulsed laser deposition.

Laser MBE of ceramic thin films for future electronics

The advantages of pulsed laser deposition for oxide film growth and of molecular beam epitaxy for two-dimensional film growth were combined to develop a method for atomically controlled layer-by-layer epitaxy of complex oxides and other ceramic thin films. This laser MBE method has been proved to be particularly useful for the purpose. Two-dimensional molecular layer epitaxy has been verified by the clear observation of RHEED intensity oscillations for the growth of various ceramics including perovskites, infinite-layer cuprates, rock salt oxides, corundum, and fluorites on oxide substrates. Epitaxial growth of BaTiO3, BaO and sapphire films was achieved even at such a low temperature as 20°C. Some phenomena indicating novel quantum effects were observed in high quality ZnO film and SrTiO3/SrVO3 superlattice, both fabricated by laser MBE. In view of the versatility and structure-sensitive properties of oxides, lattice engineering by laser MBE is expected to be a promising technology for opening a new field of oxide electronics.

Laser Ablation. Progress in Oxide Materials Research by Laser Molecular Beam Epitaxy.

The advantages of pulsed laser deposition for oxide film growth and of molecular beam epitaxy for 2-dimensional film growth have been combined to develop a method for atomically controlled epitaxy of oxide thin films and heterojunctions. Molecular layer epitaxy has been verified by the clear observation of RHEED intensity oscillations for the growths of various oxides with perovskite, infinite-layer, rock salt, corundum, and fluorite structures. Epitaxial growth of BaO and sapphire films was achieved even at such a low temperature as 20°C. New structures with exotic properties were revealed in SrTiO3/SrVO3 superlattice, infinite-layer cuprates, and ZnO hexagonal platelets film. In view of the versatility and structure-sensitive properties of oxides, this lattice engineering technology by laser MBE is expected to open a new field of oxide electronics.

Laser radiation: A tool for generation of defined thin film properties for application

Pulsed laser deposition as a method of physical vapour deposition suitable for the deposition of thin films with complex structures and compositions is briefly reviewed. Excimer, Nd:YAG and CO 2 laser radiation are comparatively investigated as a function of laser parameters and processing variables in order to deposit thin ceramic (Al 2O 3, ZrO 2, SiC, BN, BaTiO 3, Y 1Ba 2Cu 3O 7-) films on various substrates (stainless steel, hard metal, Si, ZrO 2, SrTiO 3). The methods of generating multicomponent and multilayer thin films, including the advantages of pulsed laser deposition, are described, indicating the great future application potential of pulsed laser deposition as a versatile and flexible method for the generation of films with complex compositions and structures. The laser parameters and processing variables achieve different vapour and/or plasma states, represented in the number, momentum and energy of the ensemble of species generated, which are used to deposit thin films with defined properties according to the application, in view of the mechanical-technical properties, tribological properties, fatigue and thermal barrier, illustrated by examples.