YAG Laser Deposition Research Articles

Biocompatibility of dental implants coated with hydroxyapatite using pulsed Er:YAG laser deposition.

We aimed to improve the biocompatibility and osteoinductive potential of Ti implants using a simulated intraoral hydroxyapatite (HAp) coating. We devised a novel surface treatment for aggressive induction of osteoblast adhesion and bone regeneration on the implant surface. A thin α-tricalcium phosphate (α-TCP) film was deposited on the implant surface using a pulsed Er:YAG laser. The coating was converted to HAp through artificial saliva immersion, which was confirmed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM showed needle-like HAp crystals on the Ti disks and sandblasted implant surfaces after immersion in artificial saliva for 96 h. Microcomputed tomography and histological evaluation 4 and 8 weeks after implantation into beagle dog mandibles showed that the HAp-coated implant was biocompatible and exhibited superior osteoinduction compared to that of sandblasted implants. Coating the implant surface with HAp using an Er:YAG laser has potential as a new method of the implant-surface debridement.

Pulsed laser deposition of nanostructured HgI2 on Si substrate for photodetector application

Nanostructured mercury iodide (HgI2) films were deposited on glass and silicon substrates by Nd:YAG laser deposition technique. The structural, optical and electrical properties of HgI2 films deposited at two laser energy densities of 5.1 and 6.3 J/cm2 were studied. The structural studies show that the deposited films are crystalline in nature with tetragonal phase and the film grown at 5.1 J/cm2 was highly oriented along (002) plane, whereas the film deposited at 6.3 J/cm2 was highly oriented along (114). Scanning electron microscope (SEM) investigations reveal that the film prepared at 5.1 J/cm2 has morphology of spherical nanograins and converted to nanorods morphology as laser energy density increases to 6.3 J/cm2. Energy dispersive x-ray (EDX) data confirmed that the atomic ratio of the [Hg]/[I] increases with increasing laser energy density. The optical properties showed that the optical energy gap of the films prepared at 5.1 and 6.3 J/cm2 were 3.72eV and 4eV, respectively. The electrical resistivity of the films deposited at 5.1 and 6.3 J/cm2 was found to be 8.3 × 108 and 1.03 × 109 Ω cm, respectively. The best properties of the film and the device were obtained for film deposited at laser energy density near the calculated threshold energy density. The photodetection properties of n-HgI2/p-Si heterojunction photodetector showed that the maximum responsivity of the photodetector was 0.34AW-1 at 410 nm. The effect of laser energy density on the quantum efficiency and specific detectivity of the HgI2/p-Si photodetectors was studied. The band lineup of n-HgI2/p-Si was constructed under illumination.

Synthesis and Characterization of Gallium Oxide Nanoparticles using Pulsed Laser Deposition

In this paper, the productions of gallium oxide (Ga2O3) nanoparticles were achieved via using the Nd: YAG laser deposition method with a fundamental wavelength (1064 nm). These nanoparticles were characterized by using different methods such as X-ray diffractometer (XRD), atomic force microscopy (AFM) and Ultraviolet–visible (UV–vis) spectroscopy. To examine the effects of laser energy on the properties of nanoparticles, the experimental results and theoretical considerations were prepared by the effective method of pulse laser deposition. The synthesis of Ga2O3NPs) was achieved with different ranges of energies (500 to 900 mJ). Average crystallite sizes of the synthesized nanoparticles were found to be in the range of 15-37 nm. On the other hand, the AFM images showed that the size is ranging between 60 and 85 nm. Optical parameters of the samples showed a strong dependence on average crystallite size.

Laser-assisted production of HAp-coated zirconia structured surfaces for biomedical applications

ObjectivesThe aim of this study was to develop a novel design for implants surface functionalization through the production of HAp-coated zirconia structured surfaces by means of hybrid laser technique. The HAp-rich structured surfaces were designed to avoid hydroxyapatite (HAp) coating detachment from the zirconia surface during implant insertion, thus guaranteeing an effective osseointegration. Materials and methodsThe functionalization process of zirconia surface started by creating micro-textures using a Nd:YAG laser and subsequent deposition of a HAp coating on the designated locations by dip-coating process. Afterwards, a CO2 laser was used to sinter the HAp coating. The potential of the HAp-coated zirconia structured surfaces was inspected concerning HAp bioactivity preservation, surface wettability, HAp coating adhesion to the textured surfaces and mechanical resistance of zirconia, as assessed by different approaches. ResultsThe functionalized surfaces exhibited a superhydrophilic behavior (2.30 ± 0.81°) and the remaining results showed that through the hybrid strategy, it is possible to maintain the HAp bioactivity as well as promote a strong adhesion of HAp coating to the textured surfaces even after high energy ultrasonic cavitation tests and friction tests against bovine bone. It was also verified that the flexural strength of zirconia (503 ± 24 MPa) fulfills the strict requirements of the ISO 13356:2008 standard and as such is expectable to be enough for biomedical applications. SignificanceThe promising results of this study indicate that the proposed surface design can open the window for manufacturing zirconia-based implants with improved bioactivity required for an effective osseointegration as it avoids the coating detachment problem during the implant insertion.

Cell Adhesion Ability of α-Tricalcium Phosphate Films Formed on Titanium Substrates by an Er:YAG Laser Deposition Method: Imprecations for Management of Peri-Implant Inflammation

Dental implants have been widely used to restore missing or damaged teeth. Peri-implantitis is one of the main causes of the implant loss. However, a consensus concerning clinically successful peri-implantitis treatment has not been reached at present. We have newly proposed a treatment method for the peri-implantitis by applying the intraoral laser ablation technique to induce a surface modification of dental implants. In the present study, we investigated the cell adhesion ability of α-tricalcium phosphate (α-TCP) films formed on titanium substrates by an Erbium-Doped:Yttrium, Aluminum, and Garnet (Er:YAG) laser deposition method. Cell adhesion was enhanced by the α-TCP films attached firmly to the substrates using the Er:YAG laser deposition method. This intraoral laser deposition technique can be used to recover the osteointegration ability which was lost by the treatment procedures for peri-implantitis.

Spectroscopic study the plasma parameters for SnO2 doped ZnO prepared by pulse Nd:YAG laser deposition

In this work, plasma parameters such as (electron temperature (Te), electron density (ne), plasma frequency (fp) and Debye length (λD)) were studied using spectral analysis techniques. The spectrum of the plasma was recorded with different energy values, SnO2 and ZnO anesthetized at a different ratio (X = 0.2, 0.4 and 0.6) were recorded. Spectral study of this mixing in the air. The results showed electron density and electron temperature increase in zinc oxide: tin oxide alloy targets. It was located that The intensity of the lines increases in different laser peak powers when the laser peak power increases and then decreases when the force continues to increase.

Spectroscopic study the plasma parameters for Pb doped CuO prepared by pulse Nd:YAG laser deposition

In this work, plasma parameters such as, the electron temperature )Te(, electron density ne, plasma frequency )fp(, Debye length )λD(and Debye number )ND), have been studied using optical emission spectroscopy technique. The spectrum of plasma with different values of energy, Pb doped CuO at different percentage (X=0.6, 0.7, 0.8) were recorded. The spectroscopic study for these mixing under vacuum with pressure down to P=2.5×10-2 mbar. The results of electron temperature for X=0.6 range (1.072-1.166) eV, for X=0.7 the Te range (1.024-0.855) eV and X=0.8 the Te is (1.033-0.921) eV. Optical properties of CuO:Pb thin films were determined through the optical transmission method using ultraviolet visible spectrophotometer within the range (190 – 1100) nm.

Formation of metastable phases of ferrous sulfide via pulsed Nd:YAG laser deposition: Experimental and theoretical study

Highly polymorphic ferrous sulfide exhibits attractive optical, semiconducting, magnetic and biocatalytic properties related to its phase modification. Nd:YAG laser ablation of ferrous sulfide (FeS) in vaccum results in noncongruent deposition of nanostructured FeS1-x thin films. Deposits have been carried out on Ta, Al and Cu substrates and achieved thin films were analyzed using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and electron diffraction in order to characterize morphology, chemical composition and phase transformation induced by ablative process. Round-shaped and ring-like particles, shapeless agglomerates as well as flat discontinuous areas have been observed for all the coats deposited on various substrates. However, using HRTEM, in agreement with electron diffraction, different phase compositions on various substrates have been detected. Cubic pyrite phase (FeS2) has been detected on Ta substrate. Metastable rhombohedral smythite Fe9S11 and cubic pyrite FeS2 have been found on Al substrate. And cubic pyrite FeS2, metastable rhombohedral smythite Fe9S11 and metastable orthorhombic marcasite FeS2m have been revealed on Cu substrate. The detected crystalline nanograins in all deposits were surrounded by amorphous phase. Furthermore, to gain deep insight into the electronic structure of obtained stable (cubic pyrite) and less known unstable phases (orthorhombic marcasite and rhombohedral smythite) the density functional theory is employed and important characteristics such as band gap values have been calculated.

Optimization of Humid Conditions Using an Ultrasonic Nebulizer for the Fabrication of Hydroxyapatite Film with the Er:YAG Laser Deposition Method

Restoration and maintenance of tooth substance are primary concerns in operative dentistry. Intact tooth is mainly composed of hydroxyapatite (HAp). However, there are no practical HAp materials for the treatment of tooth decay and hypersensitivity. We have newly proposed and developed a tooth restoration technique with intraoral laser ablation using an Er:YAG laser in order to form the HAp thin film on tooth surface in the atmosphere at room temperature. However, the fabricated HAp film is not uniform for the present due to the unsettled water condition at the material surface during the laser ablation. In the present study, we tried to optimize the humid condition using a nebulizer for the fabrication of HAp layer with the Er:YAG laser deposition method. The HAp layers were fabricated on a titanium substrate while changing the flow rate of water mist in order to determine the relationship between the spraying amount and the HAp layer structure. It is revealed that there exists the optimal humid condition to fabricate the uniform hydroxyapatite coating film with the Er:YAG laser deposition method.

Growth of Niobium Thin Films on Si Substrates by Pulsed Nd:YAG Laser Deposition

The growth of Nb thin films on Si(100) substrates by pulsed Nd:YAG laser deposition (PLD) under different laser fluences (4–15 J/cm2) was reported. The influence of laser fluence on ablation rate and deposition rate was discussed. X-ray diffraction (XRD) investigations of the deposited films showed an amorphous structure. The droplet density on the film surface observed by scanning electron microscopy (SEM) analyses was extremely low. It was experimentally proved that the droplets on the film surface originated from liquid phase on the target surface. Profilometric measurements of the deposited Nb films revealed a substantial asymmetry in the film thickness related to the plume deflection effect. The measured electrical resistivity of the Nb film was higher than that of high purity Nb bulk. The present investigations of ablation and deposition process of Nb thin films are related to its potential application in superconducting radio-frequency (SRF) cavities.

Effect of energy fluence and Ti/W co-deposition on the structural, mechanical and tribological characteristics of diamond-like carbon coatings obtained by pulsed Nd:YAG laser deposition on a steel substrate

To obtain diamond-like carbon (DLC) coatings, a graphite target was exposed to pulsed Nd:YAG laser radiation (1064nm wavelength) at an energy of 30mJ. The laser fluence was selected so as to initiate either effective plume ionization (80J/cm2) or the greatest deposition rate (9J/cm2). The properties of the coatings at 9J/cm2 were modified through co-deposition of Ti and W atoms. A time-of-flight method was used to study the laser plume. The deposition rate, density, surface morphology, structure and chemical state of the coatings were studied using Rutherford backscattering spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, micro-Raman spectroscopy, atomic force microscopy, and profilometry. The mechanical and tribological properties of coatings were also studied. Loads of 1N or 5N were applied to a steel ball (diameter 3mm) during ball-on-disk sliding tests; only the greater load caused noticeable wear of the coatings. While an increase in the laser fluence decreased the deposition rate by a factor of approximately 18, it also enhanced the maximum energy of ions and the average energy of atoms. As a result, the DLC coating at 80J/cm2 had a density (2.45g/cm3), sp3 content (46%), and hardness (25.4GPa) 1.1–1.2 times greater than the pure DLC coating at 9J/cm2. Moreover, the coating at 9J/cm2 had a rougher surface and microcracks that resulted in pronounced wear of the coating and the counterbody. However, accumulation of wear debris provided for the formation of a low friction tribolayer, so the friction coefficient for this coating was 0.06 or less compared to 0.1 for sliding against the coating obtained at 80J/cm2. Co-deposition of Ti and W suppressed cracking and provided smooth surface coatings. Both elements caused a decrease in the sp3 content and formed chemical bonds with C atoms. However, the increase in wear resistance was evident only with Ti co-deposition.

Characterization of nanostructured hydroxyapatite prepared by Nd:YAG laser deposition

Pulsed laser deposition, under dry and water vapor conditions, was employed to synthesize nanostructured hydroxyapatite films by pulsed laser deposition (PLD) of chlorapatite target for the purpose of coating metallic bone implants by this material. A pulsed Nd:YAG laser operating at a wavelength of 1064nm and emitting 9ns pulses was used for deposition. AFM microscopy, FTIR spectroscopy, optical microscopy, adhesion and microhardness measurements were conducted to characterize the films. The in vitro test for the synthesized hydroxyapatite was performed using simulated body fluid (SBF). The results showed a successful transformation of the chlorapatite to hydroxyapatite films characterized by all the HAp peaks with 60nm root mean square roughness, (80–327)nm grain size, and a microhardness of 512 HV.

SnO2 thin films grown by pulsed Nd:YAG laser deposition

SnO2 thin films have been deposited on glass substrates by pulsed Nd:YAG laser at different oxygen pressures, and the effects of oxygen pressure on the physical properties of SnO2 films have been investigated. The films were deposited at substrate temperature of 500°C in oxygen partial pressure between 5.0 and 125 mTorr. The thin films deposited between 5.0 to 50 mTorr showed evidence of diffraction peaks, but increasing the oxygen pressure up to 100 mTorr, three diffraction peaks (110), (101) and (211) were observed containing the SnO2 tetragonal structure. The electrical resistivity was very sensitive to the oxygen pressure. At 100 mTorr the films showed electrical resistivity of 4×10−2 Ω cm, free carrier density of 1.03×1019 cm−3, mobility of 10.26 cm2 V−1 s−1 with average visible transmittance of ∼87%, and optical band gap of 3.6 eV.

Parametric studies of diamond-like carbon by pulsed Nd:YAG laser deposition

This paper presents the results, analysis and discussions of parametric studies of diamond-like carbon (DLC) thin films by pulsed Nd:YAG laser deposition. Effects on the DLC properties and growth rate were investigated by varying the deposition parameters, namely the laser wavelength and fluence, substrate and temperature. For characterization, visible Raman spectroscopy, current-voltage measurement, optical interferometry, and optical absorption technique were employed. Comparisons were made with previous work by other workers who had also employed pulsed Nd:YAG lasers. The results also supported the subplantation mechanism for DLC formation.

Investigation of droplet formation in pulsed Nd:YAG laser deposition of metals and silicon

In the process of pulsed laser deposition of nickel (Ni) and ruthenium (Ru) thin films, the occurrence of phase explosion in ablation was found to affect the deposition rate and enhance the optical emissions from the plasma plume. Faster thin-film growth rates coincide with the onset of phase explosion as a result of superheating and/or sub-surface boiling which also increased the particulates found on the thin-film surface. These particulates were predominantly droplets which may not be round but flattened and also debris for the case of silicon (Si) ablation. The droplets from Ni and Ru thin films were compared in terms of size distribution and number density for different laser fluences. The origins of these particulates were correlated to the bubble and ripple formations on the targets while the transfer to the thin film surface was attributed to the laser-induced ejection from the targets.

Amorphous carbon–silicon heterojunctions by pulsed Nd:YAG laser deposition

Amorphous carbon (a-C) films were deposited at 10 − 4 Pa on n-Si (Si-111) and p-Si (Si-100) substrates using a pulsed Nd:YAG laser with fundamental, second- and third-harmonic outputs. These unhydrogenated and undoped a-C films were characterized by visible and UV Raman spectroscopy which indicated the presence of substantial amount of sp 3 hybridized carbon network depending on the laser wavelength. The bulk resistivity in the Au/a-C/indium tin oxide structure varied between (10 9–10 13) Ω cm — the lowest resistivity was obtained for films deposited by the fundamental laser output at 1064 nm while the highest value was by the third-harmonic laser output at 355 nm. All the a-C/Si heterostructures exhibited a nonlinear current density–voltage characteristic. Under light illumination, by taking into consideration the fill factor of ~ 0.2 for a-C/n-Si, the conversion efficiency at the highest photovoltage and photocurrent, at an illumination density of 0.175 mW/cm 2 was estimated to be ~ 0.28%.

Properties of ITO on plastics and glass by Nd:YAG laser deposition at 355 and 532 nm

Indium tin oxide (ITO) was deposited on polycarbonate (PC), polyethylene terephthalate (PET) and glass substrates at room temperature and in a low-pressure oxygen environment by a pulsed Nd:YAG laser at 355 and 532 nm. The ITO film resistivity varied with the oxygen pressure, which achieved the lowest value of 1.5 × 10 −3 Ω cm from the four-point probe measurements. The highest optical transmittance which depended on the target-to-substrate distance, was determined from UV–vis–NIR spectrophotometer. The highest optical transmission was 94% at 5 cm. The carrier concentration, of the order of 10 19 cm −3 was determined from the Hall-effect measurements. Those films deposited at 355 nm of laser wavelength did show some better properties as compared to 532 nm. Attempts were made to use these ITO-coated plastic substrates for the fabrication of a organic light-emitting device that was based on single-layer, molecularly doped (poly( N-vinyl carbazole)) (PVK) with a mixture of tris(8-hydroxyquinoline) aluminum (III) (Alq 3) and N, N'-bis (3-methylphenyl)- N, N'-bis-(phenyl)-benzidine (TPD) of 1:1 ratio.

Pulsed Nd:YAG laser deposition of indium tin oxide thin films in different gases and organic light emitting device applications

The microstructures, electrical and optical properties of indium-doped tin oxide (ITO) films, deposited on glass substrates in different background gases by a pulsed Nd:YAG laser, were characterized. The optimal pressure for obtaining the lowest resistivity in ITO thin film is inversely proportional to the molecular weight of the background gases, namely the argon (Ar), oxygen (O 2), nitrogen (N 2) and helium (He). While substrate heating to 250 °C decreased the ITO resistivity to < 4 × 10 − 4 Ω cm, obtaining the optical transmittance of higher than 90% depended mainly on the background gas pressure for O 2 and Ar. Obtaining the lowest ITO resistivity, however, did not beget a high optical transmittance for ITO deposition in N 2 and He. Scanning electron microscope pictures show distinct differences in microstructures due to the background gas: nanostructures when using Ar and N 2 but polycrystalline for using O 2 and He. The ITO surface roughness varied with the deposition distance. The effects on the molecularly doped, single-layer organic light emitting device (OLED) operation and performance were also investigated. Only ITO thin films prepared in O 2 and Ar are suitable for the fabrication OLED with performance comparable to that fabricated on the commercially available, magnetron-sputtered ITO.

Preparation of Organic Light-Emitting Thin Films by Pulsed Laser Deposition

Organic thin films such as Alq3, TPD and PVCz used for an organic electroluminescence (OEL) devices were prepared by pulsed laser deposition (PLD) technique using one of fundamental (λ=1064 nm) or second harmonic (λ=532 nm) of a Nd: YAG laser and a KrF excimer (λ=248 nm) laser. Both Alq3 and TPD films deposited by using Nd: YAG laser showed photoluminescence (PL) spectra similar to those of the targets, which have peaks of 525 nm and 420 nm, respectively. However clear PL could not be seen in the films by KrF excimer laser. Structural compositions of the Alq3 and TPD films depended on the laser wavelength. According to photon energy of a laser light, deposition process using Nd: YAG laser were dominated by the thermal effect, while the process using KrF excimer laser was influenced by a photochemical reaction.NVCz films were grown by pulsed Nd: YAG (532 nm) laser deposition method using the monomer NVCz target at the laser fluence of 300 mJ/cm2. The NVCz films had absorption spectra indicating the polymeric molecular structure similar to the spin-coated PVCz film. This research suggests the possibility of the polymer film formation using PLD process without heating and the initiator.

Properties of metal doped tungsten oxide thin films for NO x gas sensors grown by PLD method combined with sputtering process

The gas sensors based on tungsten oxide (WO 3) thin films and doped with different amount of gold (Au) or palladium (Pd) were synthesized by a new developed preparation system using the pulsed Nd:YAG (532 nm) laser deposition method combined with dc sputtering. The crystalline structure and crystallographic orientation of the prepared Au doped WO 3 (WO 3–Au) thin films, measured by X-ray diffraction system, suggested that there were distinct peaks of WO 3 (0 0 1) and (2 0 1) and weak peaks of WO 3 (1 2 0), (1 1 1), (0 0 2) and (1 1 2). The maximum sensitivity for 200 ppm NO 2 were approximately 69 for WO 3–Au thin film and 24 for WO 3–Pd thin film at the operating temperature of 300 °C, respectively. These maximum sensitivities are higher than that of the non-doped WO 3 sensor which sensitivity is about 17. This may be due to its electronic and/or chemical sensitization effect.