Rutherford Backscattering Spectrometry Analysis Research Articles

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.

Electrical and physical characterizations of the effects of oxynitridation and wet oxidation at the interface of SiO2/4H-SiC(0001) and

The effects of oxynitridation and wet oxidation at the interface of SiO2/4H-SiC(0001) and were investigated using both electrical and physical characterization methods. Hall measurements and split capacitance–voltage (C–V) measurements revealed that the difference in field-effect mobility between wet oxide and dry oxynitride interfaces was mainly attributed to the ratio of the mobile electron density to the total induced electron density. The surface states close to the conduction band edge causing a significant trapping of inversion carriers were also evaluated. High-resolution Rutherford backscattering spectroscopy (HR-RBS) analysis and high-resolution elastic recoil detection analysis (HR-ERDA) were employed to show the nanometer-scale compositional profile of the SiC-MOS interfaces for the first time. These analyses, together with cathode luminescence (CL) spectroscopy and transmission electron microscopy (TEM), suggested that the deviations of stoichiometry and roughness at the interface defined the effects of oxynitridation and wet oxidation at the interface of SiO2/4H-SiC(0001) and .

Medium energy, heavy and inert ion irradiation of metallic thin films: studies of surface nano‐structuring and metal burrowing

In context to the ion induced surface nanostructuring of metals and their burrowing in the substrates, we report the influence of Xe and Kr ion‐irradiation on Pt:Si and Ag:Si thin films of ~5‐nm thickness. For the irradiation of thin films, several ion energies (275 and 350 keV of Kr; 450 and 700 keV of Xe) were chosen to maintain a constant ratio of the nuclear energy loss to the electronic energy loss (Sn/Se) in Pt and Ag films (five in present studies). The ion‐fluence was varied from 1.0 × 1015 to 1.0 × 1017 ions/cm2. The irradiated films were characterized using Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The AFM and SEM images show ion beam induced systematic surface nano‐structuring of thin films. The surface nano‐structures evolve with the ion fluence. The RBS spectra show fluence dependent burrowing of Pt and Ag in Si upon the irradiation of both ion beams. At highest fluence, the depth of metal burrowing in Si for all irradiation conditions remains almost constant confirming the synergistic effect of energy losses by the ion beams. The RBS analysis also shows quite large sputtering of thin films bombarded with ion beams. The sputtering yield varied from 54% to 62% by irradiating the thin films with Xe and Kr ions of chosen energies at highest ion fluence. In the paper, we present the experimental results and discuss the ion induced surface nano‐structuring of Pt and Ag and their burrowing in Si. Copyright © 2016 John Wiley & Sons, Ltd.

Structural, morphological, electrical, and optical properties of silver thin films of varying thickness deposited on cupric oxide

In this investigation, silver (Ag) films of varying thickness (25–100 nm) were grown on cupric oxide (CuO) on silicon and quartz. The CuO preparation was carried out by the thermal oxidation annealing of copper (Cu) thin films deposited by DC magnetron sputtering. The physical properties of the prepared films were studied by different techniques. Rutherford backscattering spectroscopy (RBS) analysis indicated that the Ag film thickness was about 25–100 nm. X-ray diffraction (XRD) results showed that by increasing Ag thickness, the film crystallinity was improved. Also, atomic force microscopy (AFM) and scanning electron microscopy (SEM) results demonstrated that the surface morphology and the grain size were affected by the Ag film thickness. Furthermore, the electrical resistivity of films determined by four-point probe measurements versus the Ag film thickness was discussed. A reduction in the optical band gap energy of CuO is observed from 1.51 to 1.42 eV with an increase in Ag film thickness to 40 nm in Ag/CuO films.

Tailoring Electrical Transport Across Metal-Thermoelectric Interfaces Using a Nanomolecular Monolayer.

We report a 13-fold increase in electrical contact conductivity Σc upon introducing a 1,8-octanedithiol (ODT) monolayer at Cu-Bi2Te3 interfaces. In contrast introducing ODT at Ni-Bi2Te3 interfaces results in a 20% decrease in Σc. Rutherford backscattering spectrometry, X-ray diffraction and electron spectroscopy analyses indicate that metal-sulfur and sulfur-Bi2Te3 bonds at metal-Bi2Te3 interfaces inhibit chemical mixing, curtail metal-telluride formation, and suppress oxidation. Suppressing p-type Cu2Te favors electrical transport across Cu-metallized n-type Bi2Te3, whereas inhibiting the formation of Ohmic-contact-promoting NixTey compromises the electrical conductance at Ni-Bi2Te3 interfaces. Our findings illustrate that molecular nanolayers could be attractive for manipulating interface chemistry and phase formation for tailoring electrical transport across metal-thermoelectric interfaces for solid-state refrigeration applications.

Synthesis and characterization of P δ-layer in SiO2 by monolayer doping

Achieving the required control of dopant distribution and selectivity for nanostructured semiconducting building block is a key issue for a large variety of applications. A promising strategy is monolayer doping (MLD), which consists in the creation of a well-ordered monolayer of dopant-containing molecules bonded to the surface of the substrate. In this work, we synthesize a P δ−layer embedded in a SiO2 matrix by MLD. Using a multi-technique approach based on time of flight secondary ion mass spectrometry (ToF-SIMS) and Rutherford backscattering spectrometry (RBS) analyses, we characterize the tuning of P dose as a function of the processing time and temperature. We found the proper conditions for a full grafting of the molecules, reaching a maximal dose of 8.3 × 1014 atoms/cm2. Moreover, using 1D rate equation model, we model P diffusion in SiO2 after annealing and we extract a P diffusivity in SiO2 of 1.5 × 1017 cm2 s−1.

Amorphous hydrogenated carbon thin films deposited on stainless steel using high energy plasma focus device

Abstract Amorphous hydrogenated carbon (a-C:H) films have been deposited on stainless steel — AISI 304 substrates using a high energy plasma focus device in acetylene and acetylene/hydrogen discharge. The influence of hydrogen content on the microstructural and mechanical properties of hydrogenated amorphous carbon (a-C:H) films has been studied in detail. The films were deposited with the same numbers of focus shot. They were placed at the same distance from anode tip but at different angular positions with respect to the anode axis. The results of Raman spectroscopy show successful deposition of (a-C:H) films. Also, it confirms the influence of hydrogen content on the diamond character. The peak intensity ratio of the D-band to G-band (I D /I G ), the G-peak position and the full width at half maximum of the G-peak, FWHM (G), are used to characterize (a-C:H) films. The total hydrogen and copper atomic contents were obtained from elastic recoil detection analysis (ERDA) experiments and Rutherford backscattering spectrometry (RBS) analysis, respectively. Their results confirm the dependency of hydrogen and copper atomic contents on the angular positions. Field emission scanning electron micrographs show the granular surface morphology of the deposited films. X-ray diffraction (XRD) analysis confirms the amorphous structure of the films. The hardness measurement performed on the samples shows that the sample hardness is significantly improved.

Characterisation of metallic mordants in Subarctic Athapaskan quillwork: a PIXE-RBS study on replicate samples

Native American quillwork collections remain little studied due to the limited availability of quillwork material for sampling. In this paper we explore the use of non-invasive Particle Induced X-Ray Emission (PIXE) and Rutherford Backscattering Spectrometry (RBS) to characterise metallic residues in a set of modern porcupine quills prepared with a range of metallic mordants. PIXE analysis was used to determine the concentrations of various mordants present, while RBS analysis allowed additional information on the depth-profiling of the mordants at the surface of the quills to be obtained.

Effect of deposition temperature on structural, optical properties and configuration of CdSe nanocrystalline thin films deposited by chemical bath deposition

CdSe nanoparticle thin films were deposited on glass substrates by the chemical bath deposition (CBD) method at low deposition temperature ranging from room temperature up to 50°C while the pH of the bath was kept constant at 12.1. The structural and morphological variation were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) technique. The energy band gap and optical properties were characterized by the absorbance spectra. Rutherford backscattering spectroscopy (RBS) analysis reveals the excess of Cd rather than Se in depth profile along the thin film thickness. The prepared CdSe nanoparticles have cubic structure and by increasing the temperature the deposited films become continues, homogeneous and tightly adherent. The results also revealed that by increasing the deposition temperature from room temperature up to 50°C, the band gap decreases from 3.52eV up to 1.84eV.

Rutherford Backscattering Spectrometry analysis of iron-containing Bi2Se3 topological insulator thin films

Fe-containing Bi2Se3 topological insulators (TI) thin films have been grown to investigate the intricate interplay between topological order and the incorporation of ferromagnetic atoms. Here we present the quantitative characterisation of the Bi2Se3 thin films with up to 16at% Fe incorporated during the growth process on GaAs (111) substrate by Molecular Beam Epitaxy. We report the elemental composition and depth profiles of the Bi2Se3:Fe films obtained using Rutherford Backscattering Spectrometry (RBS) and their formed crystalline phase obtained by X-ray diffraction (XRD). Resistance of the TI to beam-induced damage was investigated by channelling RBS. Using the elemental composition from RBS and the thickness from XRD measurements the Fe-free film density was deduced. For Fe-containing samples, the diffraction reveals the formation of two distinct crystalline phases, as well as their intergrowth pattern, in which the basal planes of Bi2Se3 coexist with an additional Fe–Se phase. This intergrown composite, with chemical compatibility of the Fe–Se phase with the crystalline Bi2Se3 structure, preserves the intrinsic topological surface states of the TI component despite the inhomogeneous distribution of the constituent phases. RBS analysis gives the stoichiometry of the Bi2Se3, and Bi2Se3:Fe samples (estimated between 0 and 16at% Fe) and gives insights into the composition of FeSex phases present.

Identifying the dominant interstitial complex in dilute GaAsN alloys

Significant composition-dependent incorporation of N into non-substitutional sites is often reported for dilute GaAsN alloys. To distinguish (N-N)As, (N-As)As, and (AsGa-NAs) complexes, we compare Rutherford backscattering spectrometry and nuclear reaction analysis (NRA) spectra with Monte Carlo-Molecular Dynamics simulations along the [100], [110], and [111] directions. For the Monte Carlo simulation, we assume that (N-N)As is aligned along the [111] direction, while (N-As)As is aligned along the [010] direction. The measured channeling NRA spectra exhibit the highest (lowest) yield in the [111] ([100]) directions. Similar trends are observed for simulations of (N-As)As, suggesting that (N-As)As is the dominant interstitial complex in dilute GaAsN.

Interfacial reactions and surface analysis of W thin film on 6H-SiC

Tungsten (W) thin film was deposited on bulk single crystalline 6H-SiC substrate and annealed in vacuum at temperatures ranging from 700 to 1000°C for 1h. The resulting solid-state reactions, phase composition and surface morphology were investigated by Rutherford backscattering spectroscopy (RBS), grazing incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM). XRD was used to identify the phases present and to confirm the RBS results. The RBS spectra were simulated using the RUMP software in order to obtain the deposited layer thickness, composition of reaction zone and detect phase formation at the interface. RBS results showed that interaction between W and SiC started at 850°C. The XRD analysis showed that WC and CW3 were the initial phases formed at 700 and 800°C. The concentration of the phases was however, too low to be detected by RBS analysis. At temperatures of 900 and 1000°C, W reacted with the SiC substrate and formed a mixed layer containing a silicide phase (WSi2) and a carbide phase (W2C). The SEM images of the as-deposited samples showed that the W thin film had a uniform surface with small grains. The W layer became heterogeneous during annealing at higher temperatures as the W granules agglomerated into island clusters at temperatures of 800°C and higher.

Diffusion of phosphorus in olivine and molten basalt

The diffusivity of phosphorus in San Carlos olivine (SCO) was measured at near-atmospheric pressure and 650–850 °C by in-diffusion of P from a surface powder source consisting of pre-reacted SCO and AlPO 4 . The experiments were conducted in evacuated silica-glass ampoules at oxygen fugacities fixed by solid-state buffers, generally Ni-NiO but also including two experiments buffered at wustite-magnetite. Phosphorus uptake profiles were characterized by Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA). The temperature dependence of P diffusion in SCO conforms to the expected Arrhenius relation D = D 0 exp(− E a /R T ), where the constants are as follows: log( D 0 , m 2 /s) = −10.06 ± 0.80 and E a = 229 ± 16 kJ/mol. These values characterize P as a relatively slow diffuser in olivine—slower by about an order of magnitude than Cr and Ca at basalt near-liquidus temperatures—but substantially faster than Si. With a view toward modeling P uptake during rapid growth of natural olivines, P diffusion was also characterized in dry MORB basalt melt over the temperature range 1250–1500 °C at 1 GPa, using traditional diffusion couples contained in graphite. Phosphorus diffusion profiles in the quenched and depressurized samples were quantified by laser-ablation ICP/MS. Phosphorus diffusion in basaltic melt is similar to that of Si, with log( D 0 , m 2 /s) = −6.30 ± 0.7 and E a = 147 ± 22 kJ/mol. The new data for P diffusion in olivine and basalt melt can be used to explore the acquisition of fine-scale zoning in natural olivine phenocrysts through kinetic models, as well as the survival of P zoning in olivine with time spent at elevated temperature. Models of growth entrapment of a P-enriched near-surface layer in the olivine lattice indicate that crystal growth at plausible sustained rates is indeed likely to result in regions of anomalously high P content in the resulting crystal. Phosphorus concentrations above the equilibrium partitioning value can also result from development of a diffusive boundary layer in the melt against a rapidly growing crystal, but this mechanism is ineffective at typical sustained olivine growth rates, requiring dendrite-forming growth speeds. Preservation of P zoning on the scale of a few micrometers apparently requires cooling within a few months of formation of the zoning.

Rutherford backscattering spectroscopy and structural analysis of DC reactive magnetron sputtered titanium nitride thin films on glass substrates

Titanium nitride thin films were deposited on sodalime glass substrate using DC reactive magnetron sputtering technique with 99.99 % pure titanium target. High purity nitrogen and argon gases were used as the reactive and sputtering gases respectively. The sputtering deposition time was fixed at 10 min for all samples, while the chamber sputtering pressure was varied from 0.80 to 11.33 Pa with corresponding change in the nitrogen partial pressure. The films were characterized using Rutherford backscattering (RBS) spectroscopy, UV–visible spectrophotometry, scanning electron microscopy and optical microscopy. The RBS studies revealed disparity in film thicknesses and stoichiometry with respect to the deposition sputtering pressure. Up to 10 % oxygen concentration was observed in films deposited at relatively low sputtering pressures of 0.80 and 1.07 Pa, while no oxygen was detected in the films deposited at higher sputtering pressure. High pressure sputtered TiNx films showed distinct optical properties reminiscent of indium tin oxide with high transmission of 86.74 % maximum in the visible range and wide band gap energy of 3.78 eV.

Bipolar Switching Behavior of ZnO x Thin Films Deposited by Metalorganic Chemical Vapor Deposition at Various Growth Temperatures

The bipolar resistive switching behaviors of ZnO films grown at various temperatures by metalorganic chemical vapor deposition have been investigated. The ZnO films were grown on Pt/Ti/SiO2/Si(100) substrate, and the ZnO growth temperature was varied from 300°C to 500°C in steps of 100°C. Rutherford backscattering spectroscopy analysis results showed that the chemical compositions of the ZnO films were oxygen-poor Zn1O0.9 at 300°C, stoichiometric Zn1O1 at 400°C, and oxygen-rich Zn1O1.3 at 500°C. Resistive switching properties were observed in the ZnO films grown at 300°C and 400°C. In contrast, high current, without switching properties, was found in the ZnO film grown at 500°C. The ZnO film grown at 500°C had higher concentration of both nonlattice oxygen (4.95%) and oxygen vacancy (3.23%) than those grown at 300°C or 400°C. The resistive switching behaviors of ZnO films are related to the ZnO growth temperature via the relative amount of oxygen vacancies in the film. Pt/ZnO/Pt devices showed asymmetric resistive switching with narrow dispersion of switching voltage.

Solid State Reaction and Operational Stability of Ruthenium Schottky Contact-on-6H-SiC Under Argon Annealing

Thin films of ruthenium-on-6-hexagonal silicon carbide (6H-SiC) were analysed by Rutherford backscattering spectroscopy (RBS) at various annealing temperatures. Some thin film samples were also analysed by scanning electron microscope (SEM). RBS analysis indicated minimal element diffusion, and formation of ruthenium oxide after annealing at 500°C. Large-scale diffusion of ruthenium (Ru) was observed to commence at 700°C. The SEM images indicated that the as-deposited Ru was disorderly and amorphous. Annealing of the thin film improved the grain quality of Ru. The fabricated Ru-6H-SiC Schottky barrier diodes (SBD) with nickel ohmic contacts showed excellent rectifying behaviour and linear capacitance–voltage characteristics up to an annealing temperature of 900°C. The SBDs degraded after annealing at 1000°C. The degradation of the SBDs is attributed to the inter-diffusion of Ru and Si at the Schottky-substrate interface.

Interface behaviour and electrical performance of ruthenium Schottky contact on 4H-SiC after argon annealing

Rutherford backscattering spectrometry (RBS) analysis, carried out at various annealing temperatures, of a thin film of ruthenium on n-type four-hexagonal silicon carbide (4H-SiC) showed the evidence of ruthenium oxidation, ruthenium silicide formation and diffusion of ruthenium into silicon carbide starting from an annealing temperature of 400°C. Ruthenium oxidation was more pronounced, and ruthenium and silicon interdiffusion was very deep after annealing at 800°C. Raman analysis of some samples also showed ruthenium silicide formation and oxidation. The Schottky barrier diodes showed very good linear capacitance–voltage characteristics and excellent forward current–voltage characteristics, despite the occurrence of the chemical reactions and interdiffusion of ruthenium and silicon at ruthenium–silicon–carbide interface, up to an annealing temperature of 800°C.

Calculation for optimization of the experimental conditions for RBS analysis at the HUS 5SDH-2 tandem accelerator

The dependences of the depth and mass resolutions of analysis using Rutherford Backscattering Spectrometry (RBS) on some experimental conditions (such as the beam energy, the target tilting angle, etc.) have been investigated. A computer program for simulating the RBS spectra and for calculating the depth and mass resolution under different experimental conditions was developed. The results of calculation were experimentally checked by using some reference samples. The good agreements between calculated and experimental values have been found. The optimum analysis conditions over a wide range of RBS applications based on our calculation can be chosen. This investigation was conducted by using the RBS system at HUS 5SDH-2 Tandem accelerator at the Hanoi University of Science.

Definitive Insight into the Graphite Oxide Reduction Mechanism by Deuterium Labeling.

The reduction of graphite oxide is one of the most important reactions in the production of graphene in gram quantities. The mechanisms of these widely used reactions are poorly understood. The mechanism of the chemical reduction of two different graphite oxides prepared by the chlorate (Hofmann method) and permanganate methods (Hummers method) has been investigated. Three different reduction agents, lithium tetrahydridoaluminate, sodium tetrahydridoborate, and lithium tetrahydridoborate, as well as their deuterated counterparts, were used for the reduction of graphite oxide. Reduced graphite oxides were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, elemental combustion analysis, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy, and simultaneous thermal analysis. The concentration of boron incorporated into graphene was measured by prompt gamma activation analysis. Rutherford back-scattering spectroscopy and elastic recoil detection analysis were used for the determination of the elemental composition, including deuterium concentration, as evidence of CH bond formation.

Highly Conformal Amorphous W–Si–N Thin Films by Plasma-Enhanced Atomic Layer Deposition as a Diffusion Barrier for Cu Metallization

Ternary and amorphous tungsten silicon nitride (W–Si–N) thin films were grown by atomic layer deposition (ALD) using a sequential supply of a new fluorine-free, silylamide-based W metallorganic precursor, bis(tert-butylimido)bis(bis(trimethylsilylamido))tungsten(VI) [W(NtBu)2{N(SiMe3)2}2], and H2 plasma at a substrate temperature of 300 °C. Here, W(NtBu)2{N(SiMe3)2}2 was prepared through a metathesis reaction of W(NtBu)2Cl2(py)2 (py = pyridine) with 2 equiv of LiN(SiMe3)2 [Li(btsa)]. The newly proposed ALD system exhibited typical ALD characteristics, such as self-limited film growth and linear dependency of the film growth on the number of ALD cycles, and showed a high growth rate of 0.072 nm/cycle on a thermally grown SiO2 substrate with a nearly zero incubation cycle. Such ideal ALD growth characteristics enabled excellent step coverage of ALD-grown W–Si–N film, ∼100%, onto nanotrenches with a width of 25 nm and an aspect ratio ∼4.5. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy analysis confirmed that the incorporated Si and W were mostly bonded to N, as in Si–N and W–N chemical bonds. The film kept its amorphous nature until annealing at 800 °C, and crystallization happened at local areas after annealing at a very high temperature of 900 °C. An ultrathin (only ∼4 nm thick) ALD-grown W–Si–N film effectively prevented diffusion of Cu into Si after annealing at a temperature up to 600 °C.