Si Target Research Articles

Enhancement of thermal and mechanical stabilities of silicon doped titanium nitride coating by manipulation of sputtering conditions

This study investigates the influence of substrate (AISI M42 tool steel) bias voltage (from −30 to −80 V), on the mechanical properties of magnetron sputtered TiSiN coating derived from Ti and Si targets. Thermal stability, microstructure (crystallite size, microstrain, lattice constant), morphology and mechanical (hardness, Young's modulus, residual stresses) properties, of the deposited TiSiN coatings, were investigated with synchrotron powered X-ray diffraction (SR-XRD), X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and nanoindentation techniques. Rietveld analysis, of the in-situ SR-XRD, in the temperature range of 25–800 °C, demonstrated cubic TiN form in (Ti,Si)N solid solutions, with TiO2 and Ti2O3 identified at lower bias voltages. Density functional theory supplemented the experimental results.Increase in the bias voltage resulted in: (i) a decrease in Si content, (ii) significant smoothening of surface morphology, (iii) change in the phase composition and microstructure, (iv) improved oxidation resistance and thermal oxidation threshold, and (v) hardness and Young's modulus of the coatings increased up to 50% to 33 GPa and 450 GPa, respectively.

Нелинейные эффекты при распылении арсенида галлия и кремния кластерными ионами висмута

An experimental study on the influence of the energy and the number of atoms in the bombarding ions Bin+ (n = 1-4) on the sputter yield of GaAs was carried out. It was shown that the specific sputter yield Ysp nonadditively increase with an increasing of n and specific kinetic energy Esp per an atom in the bombarding ion, and the efficiency of energy transfer from bombarding ions to target atoms also increases with an increasing of n. A comparison was made with the previously obtained results for Si targets.

Nonlinear effects in the sputtering of gallium arsenide and silicon by bismuth cluster ions

An experimental study on the influence of the energy and the number of atoms in the bombarding ions Bin+ (n=1-4) on the sputter yield of GaAs was carried out. It was shown that the specific sputter yield Ysp non-additively increases with increasing n and specific kinetic energy Esp per an atom in the bombarding ion, and the efficiency of energy transfer from bombarding ions to target atoms also increases with increasing n. A comparison was made with the previously obtained results for Si targets. Keywords: ion sputtering, non-additivity factor, cluster ions, bismuth.

SiO2-coated molecularly imprinted sensor based on Si quantum dots for selective detection of catechol in river water

Selectivity is an important goal to the final analysis of targets. But for silicon quantum dots (Si QDs), a kind of QDs with low-toxic from a wide range of sources, the selective detection is mainly through the special force between Si QDs and targets. Yet it is necessary to find a way to realize the selective detection for more common target analysis. Herein, the molecularly imprinted polymers based on Si QDs (Si QDs@SiO2 @MIPs) was successfully prepared for selective detection of catechol (CT). Si QDs were firstly modified with 3-Aminopropyltriethoxysilane (APTES), the template molecule CT was effectively contacted with Si QDs after modifications, under the action of cross-linking agent tetraethyl orthosilicate (TEOS), Si QDs@SiO2 @MIPs were synthesized through the sol-gel method. Si QDs@SiO2 @MIPs displayed a strong fluorescent emission at 447 nm and were quenched in the presence of CT via dynamic quenching. Under optimum conditions, the relative fluorescent intensity of Si QDs@SiO2 @MIPs was gradually weakened in response to the increased CT concentrations in the range of 0.018–100 µM. A low detection limit of 0.018 µM for CT determination was obtained. This developed strategy was evaluated by detecting CT in the real river water samples. Satisfactory recoveries were obtained in the range of 97.77−101.70%. Moreover, the high-performance liquid chromatography (HPLC) method was conducted as a reference of CT detection, the results powerfully demonstrated the accuracy and feasibility of the method proposed in this work. Thus, the strategy is possibly a promising method for Si QDs to expand more target detection.

Compositional gradients at the nanoscale in substoichiometric thin films deposited by magnetron sputtering at oblique angles: A case study on SiOx thin films

AbstractWe demonstrate the existence of stoichiometric variations at the nanoscale when growing nanocolumnar SiOx thin films by reactive magnetron sputtering deposition at oblique angles. Results show stoichiometric variations in the range 0.3 < x < 1.3 when growing a SiO0.5 thin film. This agrees with results from a numerical growth model that obtains a shift of the stoichiometry in all nanocolumns from lower values at the side facing the Si target to higher values at the opposite side. The different momentum distribution of the gaseous reactive and sputtered species results in preferential incorporation of the latter at a particular side of the nanocolumns. The general occurrence of this mechanism during the reactive magnetron sputtering deposition of substoichiometric thin films at oblique angles is discussed.

Gold-coated silicon nanoripples achieved via picosecond laser ablation for surface enhanced Raman scattering studies

We report the results from ablation studies of polished single crystalline Si targets (of resistivity 1–10 Ohm-cm) submerged in acetone by employing the focused Airy pattern of the p-polarized laser pulses of duration ∼ 2 ps. The Airy pattern was obtained by inserting a circular aperture with hard edge before the focusing convex lens. The ablation was performed on the Si substrate at diverse scanning speeds of the motorized stage (25–600 μm/sec) with a fixed pulse energy (∼50 μJ) resulting in high/low spatial frequency laser induced periodic surface structures (HSFLIPSS/ LSFLIPSS). These are believed to be the outcome of varied electric fields and the varied pulse numbers at different scan speeds. The effective number of pulses estimated on the Si target demonstrated the surface structures with different grating periods. At lower and higher number of pulses HSFLIPSS were obtained. At an intermediate number of pulses, LSFLIPSS were observed. Further, the obtained HSFLIPSS (with grating periods ∼111 nm, 114 nm) were gold coated (25 nm) with magnetron dc sputtering technique and subsequently employed them for surface enhanced Raman scattering (SERS) studies of explosive molecules 5-amino, 3-nitro, 1,3,5-nitrozole (ANTA) at a very low concentration of 100 nM. SERS imaging of ANTA from the mentioned HSFLIPSS illustrated the uniformity in SERS signatures with an intensity variation below 10% at different locations of the SERS active platform.

Amorphous SiSn Alloy: Another Candidate Material for Temperature Sensing Layers in Uncooled Microbolometers

Herein, the prospect of using amorphous Si1–x Sn x alloys as alternative temperature‐sensing active materials in microbolometers is evaluated by studying their temperature‐dependent resistive properties along with their infrared optical properties. Si1–x Sn x thin films (200 nm thick), with varying Sn concentrations, are prepared at room temperature by cosputtering from Si and Sn targets using simultaneous radio frequency and DC magnetron sputter deposition. Low beam energy X‐ray microanalysis is used to estimate the atomic concentrations of the prepared films. Atomic force microscopy analysis shows an increase in the root‐mean‐square surface roughness of the prepared Si1–x Sn x thin films, with increasing Sn content. Sheet resistance versus temperature measurements are performed yielding temperature coefficients of resistance of 3.25, 2.65, and 1.72% K−1 at resistivity values of 116.18, 27.36, and 2.34 Ω cm for Sn concentrations of 35%, 44%, and 48%, respectively. Infrared ellipsometry measurements are performed to extract the optical properties of the Si1–x Sn x thin films and optical simulations confirm that a Fabry–Pérot cavity microbolometer configuration containing an Si1–x Sn x thin film can achieve high absorptance in the 8–12 μm band. This study shows that Si1–x Sn x alloys are a suitable, simple, and low‐cost replacement for thermometer layers used in uncooled infrared microbolometers.

Metal-insulator multilayer precursors for enhanced Sm2+ absorption and Tm2+ luminescence in SiAlO thin films prepared by magnetron sputtering

Silicon-aluminum-oxigen (SiAlO) coatings doped with Sm2+ and prepared by reactive magnetron co-sputtering of Si, Al, and Sm targets, are attractive for luminescence solar concentrator applications but suffer from the low absorption between 300 and 600 nm. This article reports that the main cause of low absorption is a high concentration of undesired Sm3+. This finding is supported by optical transmittance, photoluminescence emission and excitation characterization, and X-ray photoelectron spectroscopy data of the Sm's 3d5/2 edge. We present an alternative deposition process for obtaining Sm doped SiAlO layers with enhanced Sm2+ absorption by incorporating Sm through the use of multilayer thin-film precursors composed of metallic Sm and SiAlO layers. After thermal post-deposition treatments, diffusion and reaction of the metallic Sm layers with the SiAlO host results in coatings showing the characteristic 5d → 4f transitions of Sm2+ in the region between 250 and 600 nm which were not detectable in Sm-doped single layers. This same deposition strategy produces Tm doped SiAlO coatings with Tm2+‘s characteristic luminescence at 1132 nm when the SiAlO host is in the mullite composition region. The photoluminescence excitation spectrum of Tm2+ is compared to phosphor with similar composition and covers the range between 300 and 700 nm.

Optimization of a short-pulse-driven Si Heα soft x-ray backlighter

High backlighter brightness is important to maximize the number of detected photons in radiography experiments and to minimize the background while backlighting high-energy-density plasmas with strong self-emission. Several different configurations were tested to improve the brightness of the Si Heα x-ray line emission at a photon energy of 1865 eV from high-energy (>1 kJ), short-pulse (∼20 ps), laser-driven backlighter targets. The emission from low-density SiO2 foam targets, the effects of a laser prepulse, and Si targets with a CH “shield” that form a small cavity were compared to solid-density, flat Si targets. The CH “shield” targets showed the best performance with a>5×improvement in time-integrated emission and an x-ray pulse duration of ∼25 ps with no measurable spectral shift of the Si Heα emission line. A conversion efficiency from laser light into Si Heα photons on the order of 1 × 10–5 was inferred from the data.

Incorporation of colloidal Si nanoparticles into chemical bath solutions to synthesize nc-Si/CdS nanocomposite thin films

Colloidal silicon nanoparticles (nc-Si) with diameters below 10 nm, were synthesized by the laser ablation of solids in liquids technique by ablating a bulk Si target immersed in deionized water. The obtained suspension was diluted in deionized water at volume ratios of 1:16, 2:15 and 4:13 in order to have different concentrations of Si nanoparticles. Each colloidal suspension was used to prepare precursor solutions for chemical bath deposition of nc-Si/CdS nanocomposite thin films with different nc-Si contents. According to UV–Vis Results, nanocomposite films reached optical transmission values of 90–98% for wavelengths above 500 nm, while the pure CdS reached values near 65%. Furthermore, the band gap increases linearly with nc-Si volume ratio in the bath. Photoluminescence emissions shifted to lower energies as nc-Si volume ratio increased. A signal associated to nanocrystalline Si appeared at 600 nm for nanocomposite films. Structural characterization showed no significant changes for nc-Si containing samples. • The laser ablation in solids technique can be combined with chemical bath deposition to synthesize nanocomposite thin films. • Nanocomposite films are crystalline. • Visible light emission from silicon nanoparticles embedded in CdS can be obtained.

Structure and Properties of DLC Films Deposited on Mg Alloy at Different C2H2 Flows of Magnetron Sputtering Process

Diamond-like carbon (DLC) film is widely used due to its excellent properties, such as high hardness and high wear resistance. To investigate the advantages of DLC film applied on the surface of Mg alloy, direct current (DC) pulse magnetron sputtering was used to prepare DLC film via plasma sputtering a graphite target and introducing C2H2 gas. The silicon interlayer was fabricated by sputtering the Si target. A scanning electron microscope (SEM), transmission electron microscope (TEM), a nano-indentation instrument, an electrochemical workstation and a pin-on-disc tester were employed to obtain the surface morphology, microstructure, mechanical properties, corrosion behavior and wear resistance of the obtained film, respectively. The results show that the DLC films are dense and compact, and the structure changes from amorphous to nanocrystalline with the increase of C2H2 flow. The film prepared at low C2H2 flow has larger surface roughness, lower deposition rate, higher hardness and elasticity modulus, poorer corrosion resistance and better wear resistance, compared with the film prepared at higher acetylene flow. The self-corrosion potential of the obtained DLC film is higher than −0.95 V, the corrosion current density is 10−7 A/cm2 orders of magnitude, and the wear rate is 10−9 mm3/Nm orders of magnitude. The friction coefficient of the film is less than 0.065, the hardness is 17.3 to 22.1 MPa, and the elastic modulus is 145 to 170 MPa. The DLC films obtained on the surface of AZ91 alloy have good comprehensive properties.

Si sputtering yield amplification: a study of the collisions cascade and species in the sputtering plasma

The sputtering yield amplification (SYA) is a phenomenon based on doping a sputtering target with atoms of higher atomic mass. This doping changes the depth and the direction of the collision cascade in the target surface promoting a higher ejection of target atoms. In this work, we present a new way of generating the SYA phenomenon without the need of expensive and complex deposition systems. This was accomplished by increasing the working pressure and adding small pieces of W, as dopant element, on the racetrack of a Si target. The physical phenomena necessary to promote the SYA, for our experimental parameters, were analysed in two different deposition chambers and two sizes of sputtering targets. Based on the collisions in the gas phase, a calculation on the number of W atoms returning to the racetrack area was made, considering the number of atoms deposited on the thin films, to determine their effect on the cascade of collisions. In addition, calculations with the simulation of metal transport code were developed to determine the location on the racetrack zone the returning atoms were redeposited. By using reference samples placed on the racetrack of the Si target, we found that the percentage of SYA depends on the number of dopant atoms redeposited as well as the depth distribution these atoms had in the racetrack surface.

Effect of microstructure and mechanical properties on the tribological and electrochemical performances of Si/DLC films under HCl corrosive environment

Si-doped diamond-like carbon (Si/DLC) films appear very attractive due to their superior mechanical and tribological properties and chemical inertness. In the present work, Si/DLC films with silicon concentration from 1.64 to 15.32 at.% were fabricated on 304 stainless steel by adjusting Si target current using unbalanced magnetron sputtering system. The microstructure, surface morphology and mechanical properties of the films with different Si concentration, as well as the tribological and electrochemical properties of the films under HCl corrosive environment were systematically investigated. Results showed that Si doping increased the sp3 CC content, hardness, and elastic modulus of as-fabricated films, lowered the residual stress, but deteriorated the adhesion strength. At the same time, the appropriate Si concentration was conducive to low surface roughness and dense microstructure. The Si/DLC films presented good tribological performances in 1 M HCl solution, including low friction coefficient and wear rate. The degradation of tribological properties was attributed to the synergistic effect of less solid lubrication, declined adhesion strength, worse resistance to elastic and plastic deformation. The wear mechanism was mainly dominated by abrasive wear. Furthermore, the Si/DLC film with 15.32 at.% Si provided the best corrosion resistance, which benefited from its dense structure, higher thickness, and the highest sp3 CC content.

Characterization of Si/Mg<sub>2</sub>Si multilayer mirrors manufactured by sputtering of Mg and Si targets

Characterization of Si/Mg<sub>2</sub>Si multilayer mirrors manufactured by sputtering of Mg and Si targets

Pulsed production of antihydrogen

Antihydrogen atoms with K or sub-K temperature are a powerful tool to precisely probe the validity of fundamental physics laws and the design of highly sensitive experiments needs antihydrogen with controllable and well defined conditions. We present here experimental results on the production of antihydrogen in a pulsed mode in which the time when 90% of the atoms are produced is known with an uncertainty of ~250 ns. The pulsed source is generated by the charge-exchange reaction between Rydberg positronium atoms—produced via the injection of a pulsed positron beam into a nanochanneled Si target, and excited by laser pulses—and antiprotons, trapped, cooled and manipulated in electromagnetic traps. The pulsed production enables the control of the antihydrogen temperature, the tunability of the Rydberg states, their de-excitation by pulsed lasers and the manipulation through electric field gradients. The production of pulsed antihydrogen is a major landmark in the AEbar{g}IS experiment to perform direct measurements of the validity of the Weak Equivalence Principle for antimatter.

Preparation and tunable optical properties of amorphous AlSiO thin films

Thin films in the aluminosilicate (AlSiO) system containing up to 31 at. % Al and 23 at. % Si were prepared by reactive RF magnetron co-sputtering in order to investigate the dependence of film formation and optical properties on substrate temperature and Si and Al contents. The obtained films were amorphous with smooth microstructure. The growth rate at different substrate temperatures ranged from 1.2 to 3.3 nm/min and increase with increasing the Si target power. The roughness decreases and thickness increases with increasing Si content. The thickness of the films grown at a deposition temperature of 100 °C is found to be higher than the films deposited at 300 and 500 °C. The AlSiO-coated glasses have a higher transmission in the visible region than the uncoated glass. The spectroscopic ellipsometry analysis reveals that the refractive index value decreased with decreasing the Al content, having extinction coefficient values of zero in the measured spectral region and band gap values ≥ 3.4 eV. The obtained thin films have over 90% transmittance in the visible range and no systematic variation of transmittance was observed with substrate temperature. The results suggest that glass substrate coated with AlSiO thin films have improved optical properties.

Change in ion sputtering coefficients of targets due to cross-dusting during simultaneous operation of two sputters

The influence of cross-dusting of silicon and metal targets simultaneously sputtered by argon ions on partial sputtering coefficients of targets materials components is studied to take this effect into account in the technology of gradient optical coating deposition. The effect has been numerically simulated as series of cascades of binary collisions of bombarding ions and recoil atoms with target atoms. Addition of metal atoms (Ti, V, Zr, Hf, Nb and Ta) to the Si target enhances the partial sputtering of Si atoms but addition of Si atoms to the metal targets decreases the partial sputtering of metals atoms. Also the coefficients of reflection (back scattering) of the bombarding argon ions from the targets with different additives have been calculated. It is possible that enhanced sputtering of Si atoms from the coatings with a “heavy” component by reflected neutralized ions would lead to dusting the “heavy” target by silicon.

Structural Properties of Fe3Si thin Films at Different Pulsed-Laser-Deposition Modes

The formation and investigation of Fe3Si thin films by pulsed laser deposition is reported. The structural properties depending on the formation parameters are investigated. Three different approaches to the synthesis of iron-silicide thin films by pulsed laser deposition are explored: deposition from a stoichiometric alloy target, the simultaneous co-deposition of pure Fe and Si targets by two lasers and the single-laser cyclic co-deposition of pure targets.

Microstructure Evolution and Mechanical Behavior of Mo–Si–N Films

The molybdenum silicon nitride (Mo–Si–N) films were deposited by a radio frequency (RF) magnetron reactive dual-gun co-sputtering technique with process control on input power and gas ratio. Composition variation, microstructure evolution, and related mechanical and tribological behavior of the Mo–Si–N coatings were investigated. The N2/(Ar + N2) flow ratios were controlled at 10/20 and 5/20 levels with the tuning of input power on the Si target at 0, 100, and 150 W. As the silicon contents increased from 0 to 33.7 at.%, the film microstructure evolved from a crystalline structure with Mo2N and MoN phases to an amorphous feature with the Si3N4 phase. The analysis of selected area electron diffraction patterns in TEM also indicated an amorphous feature of the Mo–Si–N films when Si content reached 20 at.% and beyond. The hardness and Young’s modulus changed from 16.5 to 26.9 and 208 to 273 GPa according to their microstructure features. The highest hardness and modulus were attributed to nanocrystalline Mo2N and MoN with Si solid-solution. The crystalline Mo–Si–N films showed a smooth tribological track and less wear failure was found. In contrast, the wear track with severe failures were observed for Mo–N and amorphous Mo–Si–N coatings due to their lower hardness. The ratios of H/E and H3/E2 were intensively discussed and correlated to the wear behavior of the Mo–Si–N coatings.

Magnesium, silicon, and hydroxyapatite deposition on the Ti-xNb-2Ag-2Pt alloy by co-sputtering after nanotube formation

In this study, to improve the material properties and biocompatibility of Ti alloys, Ti-xNb-2Ag-2Pt alloy was prepared by adding niobium (Nb), silver (Ag), and platinum (Pt). The surface was treated by anodization, and surface treated alloy was coated with HA, Mg, and Si through magnetron sputtering. Ti-xNb-2Ag-2Pt alloys were based on a Ti-2Ag-2Pt alloy, and the Nb content was changed to 10, 30, and 50 wt%. The nanotubes were formed by anodization in 1 M H3PO4 and 0.8 wt% NaF electrolyte, following which the sample was coated by RF-and DC-magnetron sputtering using HA, Mg, and Si targets. The surface morphology and material properties of Ti-xNb-2Ag-2Pt alloys were analyzed by optical microscopy (OM), nano-indentation tests, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometer (EDS), and X-ray diffractometer (XRD).In the case of Ti-xNb-2Ag-2Pt alloys, the martensitic and needle-like structure decreased and the equiaxed structure increased with increasing Nb content. The elastic modulus of Ti-50Nb-2Ag-2Pt alloys was lower than that of Ti-10Nb-2Ag-2Pt alloys. As the Nb content increased, the shape of the nanotubes changed irregularly and nanotube diameter of Ti-xNb-2Ag-2Pt alloys decreased. Also, nanotube diameter after co-sputtered Mg and Si on HA coated surface decreased compared to only HA deposited nanotubes.