Rutherford Backscattering Spectrometry Analysis Research Articles

Direct growth of highly oriented GaN thin films on silicon by remote plasma CVD

We report on low-temperature (500 °C) and low-pressure (0.3 mbar) direct growth of GaN thin films on silicon (100) substrates using remote plasma chemical vapour deposition (RP-CVD). In the custom-designed reactor, an RF inductively coupled plasma is generated remotely from the substrate’s area to facilitate the decomposition of group-V precursor, N2 with added H2, while group-III precursor trimethylgallium (TMGa), is directly injected into the growth chamber mixed with H2 carrier gas. Growth parameters such as RF power, process pressure and gas flow rates have been optimized to achieve a film growth rate of about 0.6 µm h−1. Several characterization techniques were used to investigate the plasma and the properties of the grown thin films in terms of their crystallinity, morphology, topography, and composition. The films are highly textured with a preferential orientation along the c-axis of the wurtzite structure. They present a small roughness in the nanometer range and a columnar microstructure with a grain size of one hundred nanometer, and a gallium polarity (+c plane oriented). Rutherford backscattering spectrometry and nuclear reaction analysis show that the chemical composition is homogeneous through the depth of the layer, with a III/V ratio close to 1, a very low content of oxygen (below the detection limit ∼1%) and a carbon content up to 11%. It was shown that the increase of plasma power helps to reduce this carbon contamination down to 8%. This research paves the way for a growth method compatible with cost reduction of III–V thin film production achieved through reduced gas consumption facilitated by RP-CVD operation at low pressure.

A machine learning approach to self-consistent RBS data analysis and combined uncertainty evaluation

We introduce a machine learning approach designed for the self-consistent analysis of data acquired through simultaneous Rutherford backscattering spectrometry (RBS) in multiple scattering geometries, with subsequent determination of the analysis uncertainty. Using a simulated data set, the successful self-consistent evaluation of up to six simultaneous RBS data collections was achieved by employing artificial neural networks (ANN). The results demonstrate enhanced accuracy and precision when concatenating multiple RBS spectra as input to the ANN. The precision was quantified through the combined uncertainty, encompassing the ANN random uncertainty, the ANN systematic uncertainty, and the model robustness. While applied to only RBS analysis, this approach holds promise for advancing the analysis of data collected by next-generation RBS equipment and Total ion beam analysis, offering a robust and efficient framework for future research.

Enhanced accuracy through machine learning-based simultaneous evaluation: a case study of RBS analysis of multinary materials

We address the high accuracy and precision demands for analyzing large in situ or in operando spectral data sets. A dual-input artificial neural network (ANN) algorithm enables the compositional and depth-sensitive analysis of multinary materials by simultaneously evaluating spectra collected under multiple experimental conditions. To validate the developed algorithm, a case study was conducted analyzing complex Rutherford backscattering spectrometry (RBS) spectra collected in two scattering geometries. The dual-input ANN analysis excelled in providing a systematic analysis and precise results, showcasing its robustness in handling complex data and minimizing user bias. A comprehensive comparison with human supervision analysis and conventional single-input ANN analysis revealed a reduced susceptibility of the dual-input ANN analysis to inaccurately known setup parameters, a common challenge in material characterization. The developed multi-input approach can be extended to a wide range of analytical techniques, in which the combined analysis of measurements performed under different experimental conditions is beneficial for disentangling details of the material properties.

Comparison between conventional Si and new generation of SiC detector for high proton energy spectrometry

A SiC Schottky diode and a Si surface barrier detector have been compared during Rutherford backscattering spectrometry (RBS) using 2–3 MeV proton beams. Both detectors are suited to detect high energetic ions with high-energy resolution for spectroscopic analysis. The correlations between the detector parameters and the surface passivating layers, ion energy and current dependence, ion penetration depth, detection efficiency and energy resolution, are outlined. Comparative RBS analysis performed using SiC and Si detectors has been investigated to highlight the advantages and disadvantages of the use of SiC with respect to the traditional Si junction detector. RBS spectrometry has been carried out using projectiles of proton incident on different targets to analyse their composition and thickness by the detection of the backscattered ions revealed by Si and SiC detectors.

Structural and electrical properties of (Cr1−x ,V x )N thin films epitaxially grown on MgO(001) substrates

(Cr1−x ,V x )N thin films were grown on MgO(001) substrates by pulsed laser deposition, and their structural and electrical properties were characterized. The composition of the thin films was determined by Rutherford backscattering spectroscopy and X-ray fluorescence analysis. X-ray diffraction analyses confirmed that the thin film grown epitaxially and the lattice constant decreasing as x increased. The temperature dependence of the electrical resistivity of the (Cr1−x ,V x )N thin films indicated that CrN and VN exhibited metallic behavior, whereas (Cr1−x ,V x )N exhibited semiconductor behavior. The semiconductor behavior of (Cr1−x ,V x )N might be associated with Anderson localization in addition to Mott–Hubbard interactions.

Cryogenic heavy ion RBS-ERDA depth profiling of ion implanted PET films

The analysis of thin films using heavy ions offers some specific advantages over traditional light ion beam analysis techniques. In this work, polyethylene terephthalate (PET) substrate was implanted with 150 keV Ag+-ions at low temperature at fluences of 1.00 x 1016 and 5.00 x 1016 ions/cm2. A newly constructed low temperature chamber equipped with heavy ion Rutherford Backscattering Spectrometry (HI-RBS) and Elastic Recoil Detection Analysis (HI-ERDA) detectors was used for sample characterisation, using 14 MeV 28Si4+-ions at an irradiation fluence of about 2.40 x 1013 ions/cm2. The analyses were carried out at room temperature and with the sample holder cooled to liquid nitrogen temperature. Silicon beam irradiation effects on the PET were then compared at room- and low-temperature measurements. Significant hydrogen loss of about 64 % relative to pristine PET was observed for room-temperature measurements, whereas for low-temperature analyses the hydrogen loss was about 12 %. The significant release of hydrogen atoms from the surface region of the PET was accompanied by a drastic change in the surface layer composition. For room-temperature measurements, there was surface enhancement of the carbon content by about 31 %, while for low-temperature measurements the accumulation was about 9 % compared to the nominal 45 % content in pristine PET.

Correlated characterization of 20Ne-implanted targets using nuclear reaction analysis, Rutherford backscattering spectrometry, and ion transport modeling

We present the preparation and characterization of a large sample of implanted noble gas targets for use in precision nuclear astrophysics measurements with intense proton beams. Tantalum and titanium backings were prepared using wet-acid etching, outgassed via resistive heating, and implanted with 20Ne+ beams from differing ion sources. These experimental targets were investigated using both nuclear reaction analysis techniques on the 1169-keV resonance in 20Ne(p, γ)21Na and Rutherford backscattering spectrometry analysis with 2-MeV α-particle beams. Results from these analyses reveal small target-to-target variations in stoichiometry, while exhibiting excellent agreement independent of ion-beam analysis method. We also present a self-consistent validation of the nuclear reaction analysis results using ion transport simulations in TRIM-2013 that rely on input parameters from SIMNRA scattering-yield fits to Rutherford backscattering spectra. In addition to a complete description of the implantation profile, this analysis method provides an alternate solution for characterizing a large sample of implanted targets when no suitable resonances are available for nuclear reaction analysis.

The sensory and photo-catalytic properties of graphene oxide and polyimide thin films implanted by 1500 keV Cu ions

Thin films of polyimide (PI) and graphene oxide (GO) were exposed to the accelerated Cu-ions with an energy of 1500 keV at different ion fluences (3.75 × 1012; 3.75 × 1014; 1 × 1016) cm−2. The reason for Cu-ion irradiation lies in the modification of thin PI and GO layers and their subsequent use in electronics, photo-catalysis and humidity sensing. It was expected that three ways would primarily carry out modification: i) interaction of the accelerated ions with atoms and electrons of the irradiated films, ii) implantation of Cu ions inside the matrices and their attachment to the structures in the form of CuO, and iii) formation of C and Cu aggregates and Cu nanoparticles in the subsurface layer to form an electrically conductive network. The effects of the interactions of energetic Cu-ions on the PI and GO matrices, including the prediction of the depth of Cu ion penetration, were simulated by SRIM software. Elemental changes, including the depth profiles of implanted Cu-ions, were investigated by Rutherford backscattering spectrometry (RBS) and Elastic recoil detection analysis (ERDA). Changes in the chemical bonding on the PI and GO surfaces were studied by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The effect of energetic Cu-ions on the surface morphology was analyzed by Atomic force microscopy (AFM). For the possible application of PI and GO composites in electronics and sensory, the sheet resistivity were measured by the two- point method and the effect of air humidity on electrical properties was studied. Furthermore, the degradation of Rhodamine B solution in the presence of prepared composites under UV-light irradiation was measured for possible use in photo-catalysis. It was found that the interaction of Cu- ions with the matrix leads to the release of oxygen and hydrogen, resulting in an increase in carbon concentration. The increase in carbon concentration leads to an increase in the electrical conductivity of both materials. The irradiation with Cu ion fluence of 1 × 1016 cm−2 probably formed in PI a subsurface conducting network that reduced the sheet resistivity by almost eleven orders of magnitude. The ion irradiation by Cu ion with fluences below 1 × 1016 cm−2 enhances the photo- catalytic properties of both used materials and the best result was achieved in the case of PI irradiated by the ion fluence of 3.75 × 1014 cm−2.

Interfacial reaction and phase formation in Pd/ZrO/Pd/TiO/Pd multilayer stack on silicon substrate: Investigated by ion beam techniques

The influence of the annealing temperature on the stability of the multilayer stack Pd/Zr/Pd/Ti/Pd thin films system, with both Zirconium (Zr) and Titanium (Ti) layers containing oxygen (O), deposited on silicon substrate was investigated. Using the in-situ real-time Rutherford backscattering spectrometry (RBS) analysis, the multilayer stacked thin film systems were linearly heated, at a constant heating rate, from room temperature up to 600 °C and found to be stable up to ∼370 °C whereby the inter-diffusion of Palladium (Pd), from both the third and the fifth layer, towards the forth layer comprising of Ti and O in 2:1 ratio, was observed. Moreover, the Ti, from the Ti–O layer, was found to spread to low and higher channels during Pd diffusion. Above 480 °C the second reaction was observed between Pd and silicon substrate, forming a hexagon silicide phase (Pd2Si) confirmed by X-ray diffraction. The thickness of the Pd2Si layer increased with increasing temperature and its activation energy was estimated to be 2.30 eV, which is about 1.10 eV and 0.65 eV higher than the activation energy of the Pd2Si phase formation at 100 °C and 250 °C, respectively. Therefore, the activation energy of the Pd2Si phase depends on the temperature at which the phase is growing.

The catalytic, sensory and electrical properties of GO, PI and PLLA implanted by low-energy copper ions

In this work, we focused on ion beam modification and doping of graphene oxide (GO), polylactic acid (PLLA) and polyimide (PI) by low-energy Cu ions for a study of catalytic, sensory and electrical properties. We implanted the GO and polymer samples with 20 keV Cu ions with three implantation fluences from 3.75 × 1012 cm−2 to 1.0 × 1016cm−2. As follows, the elemental composition and structural changes were studied using Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Rutherford Back-scattering Spectroscopy (RBS) and Elastic Recoil Detection Analysis (ERDA). The surface morphology was analysed using Atomic Force Microscopy (AFM). The electrical properties of prepared structures were characterized by 2-point sheet resistivity measurement and the sensory properties were analysed in an atmospheric chamber and compared with BME280 combined humidity/temperature/pressure sensor. The photo-catalytic properties were studied by Rhodamine-B disintegration under UV light. Ion beam implantation has been applied successfully to the functionalization of used samples. The electrical conductivity increased with increasing Cu ion fluence. The GO and PI demonstrated effective sensory and photo-catalytic performance and the best result was achieved for Cu ion fluence of 3.75 × 1012 cm−2.

Characterization of magnesium channeled implantation layers in GaN(0001)

The effect of Mg channeled implantation into epitaxially grown gallium nitride (GaN) was studied using Hall-effect measurements, photoluminescence (PL), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and Rutherford backscattering spectroscopy (RBS). In the channeled implantation, deeper profiles were obtained with lower implantation energy and less damage compared to random implantation. The donor–acceptor pair signal at ∼3.28 eV, suggesting that Mg is activated, was confirmed by PL measurement when the ion dose and implantation energy are 1 × 1014 cm−2 and 20 keV, respectively. However, even with channeled implantation, several types of defects including point defects and oblong defects as seen in the random implantation were observed by TEM/STEM analysis. RBS analysis showed slightly worse crystal qualities in channeled implantation compared to non-implanted samples. Mg channeled implantation is useful to achieve deeper profiles (>1 μm), but further condition tuning of process will be necessary for practical application.

Preparation of wafer-scale highly conformalamorphous hafnium dioxide thin films by atomic layer deposition using a thermally stable boratabenzene ligand-containing hafnium precursor

In the present study, HfO2 thin films were fabricated via atomic layer deposition (ALD) using a novel heteroleptic metal organic precursor [tris (dimethylamino) dimethylaminoboratabenzene hafnium] [η6:η1-(C5H5BNMe2)Hf(NMe2)3; (BBHf)] along with O2 as the oxygen source at a range of growth temperatures (i.e., 150–350 °C). This novel precursor is a heteroleptic complex synthesized by the introduction of a boratabenzene ligand (BB) into the parent Hf metal sphere to achieve an enhanced thermal stability. In this system, O2 is used as a mild oxygen-containing reactant to replace the typically employed ozone (O3). Distinctive self-limiting deposition was established with a comparatively high growth per cycle value of 0.068 nm, and linear growth was observed as a function of the ALD cycle number. Thermal decomposition was not detected at or below 350 °C, thereby indicating the improved thermal stability compared to when frequently used Cp (cyclopentadienyl)-amide precursors are employed. Under the ALD deposition conditions employed herein (275 °C), a complete step coverage was achieved with a good conformality on high aspect ratio dual trenches [top and bottom widths = 40 and 15 nm, respectively, aspect ratio (AR) ≈ 6.3], and uniformity was obtained on the large planar substrate (15 cm diameter). Upon annealing at 700 °C, the as-grown film formed an amorphous structure with a slightly enhanced crystallinity, while annealing at 850 °C led to the generation of nanocrystalline HfO2 films with amorphous structures, as indicated by X-ray diffraction measurements. The as-grown films were determined to be slightly rich in oxygen compared to the stoichiometry of HfO2, although they also contained significant amounts of residual impurities, such as H, B, and C (∼6, 6, and 7 at.%, respectively), as confirmed by Rutherford backscattering spectrometry and elastic recoil detection analyses. The impurity levels were further reduced by increasing the growth temperature and by subsequent post-annealing, as evidenced by X-ray photoelectron spectroscopy and secondary-ion mass spectrometry analyses. Finally, ellipsometry analysis was performed to measure the optical properties of the prepared ALD-HfO2 thin films. It is expected that the described process may be of significance in the preparation of high-k films wherein thermally stable amorphous films with extremely conformal and uniform coatings are required to fabricate next-generation electronic devices.

Influence of swift heavy ion irradiation on bimetallic gold-silver nanoparticles in dielectric matrices and their optical properties

Nanosized gold-silver (AuAg) alloy nanoparticles (NPs) of sizes, 2 nm -25 nm embedded in fused quartz are synthesized using sequential implantation and post annealing at 900℃ for 1 h in Argon environment. The post annealed film is irradiated using swift heavy ions (SHI), 120 MeV Ag ions to investigate the effect of electronic energy deposition, (Se×ϕ), on size, shape and composition of the alloy NPs. Transmission electron microscopy (TEM) analysis of the as- implanted AuAg film reveals the formation of small sized, 1.8 nm-3.5 nm, bimetallic AuAg NPs. Rutherford backscattering spectroscopy (RBS) spectra along with its fitted graph convey the annealing induced out diffusion, mixing and formation of larger sized, 2 nm -25 nm, alloy NPs through Ostwald ripening. SHI irradiation results in deformation in shape from spherical to ellipsoidal alloy NPs with major axis align along the beam direction and the average aspect ratio is about 1.20. RBS analysis results convey the formation of Ag enriched alloy NPs after irradiation. The smaller nanoparticles are found dissolved while larger ones grow and elongate along the ion beam direction. SPR properties are modified by SHI induced processes of melting, sputtering and re-precipitation in the ion tracks.The un-irradiated film exhibits a single intense SPR peak at 536 nm, while the irradiated film gives rise two SPR peaks: Ist, a blue shifted SPR peak from 536 nm to 515 nm with significantly reduced intensity and much wider FWHM; and, IInd, a small SPR peak around 460 nm. SHI induced modifications on the NPs are understood in terms of thermal spike model. The detailed analysis shows that SHI can be used as a tool to tailor size, shape and composition of the bimetallic AuAg alloy NPs and their SPR properties.

Characterization of agricultural biomass by particle induced x-ray emission and Rutherford backscattering techniques

Particle-induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) techniques are non-destructive elemental analyses method with high sensitivity and capability for multi-element analysis in one spectrum. These techniques have not been used for the elemental characterization of biomass. So, this study characterized and evaluated elemental compositions of some selected agricultural biomass (Palm kernel shell (PKS), coconut shell (CS), cassava peel (CP), and Africa star apple seed shell (ASASS)) using combined PIXE and RBS. The results were compared with the ultimate analysis and optical-based techniques. Results from PIXE and RBS analysis confirm the presence of C, O, S, Na, Mg, P, Si, K, Ca, Fe, Cl, Al, Ti, Cu, and Zn in the tested biomass samples. Estimation of RBS accuracy by direct comparison with the ultimate analysis of some biomass samples showed a wide disparity of ±10.7% and ±2.57% in the RBS data for carbon and oxygen in PKS and a disparity of ±5.22% and ±0.55% in the RBS data for carbon and oxygen in coconut shell respectively. In the case of minor and trace element concentrations, estimated errors in the range of 1–3% and 2.68–4% were observed for optically based techniques compared with PIXE and RBS analysis, respectively.

Compositional and Structural Modifications by Ion Beam in Graphene Oxide for Radiation Detection Studies

In the present study, graphene oxide foils 10 μm thick have been irradiated in vacuum using same charge state (one charge state) ions, such as protons, helium and oxygen ions, at the same energies (3 MeV) and fluences (from 5 × 1011 ion/cm2 to 5 × 1014 ion/cm2). The structural changes generated by the ion energy deposition and investigated by X-ray diffraction have suggested the generation of new phases, as reduced GO, GO quantum dots and graphitic nanofibers, carbon nanotubes, amorphous carbon and stacked-cup carbon nanofibers. Further analyses, based on Rutherford Backscattering Spectrometry and Elastic Recoil Detection Analysis, have indicated a reduction of GO connected to the atomic number of implanted ions. The morphological changes in the ion irradiated GO foils have been monitored by Transmission Electron, Atomic Force and Scanning Electron microscopies. The present study aims to better structurally, compositionally and morphologically characterize the GO foils irradiated by different ions at the same conditions and at very low ion fluencies to validate the use of GO for radiation detection and propose it as a promising dosimeter. It has been observed that GO quantum dots are produced on the GO foil when it is irradiated by proton, helium and oxygen ions and their number increases with the atomic number of beam gaseous ion.

(Invited) Comparison of Compositional, Optical and Mechanical Properties of Sicn Thin Films Prepared By Ecr-PECVD with Different Hydrocarbon Precursors

Silicon carbon nitride (SiCN) ternary compounds present remarkable mechanical strength, bandgap tunability, optical responsivity in the UV region, and dielectric performance in microelectronics due to the combined features of silicon nitride (SiN), silicon carbide (SiC), and carbonitride (CN) [1]. The SiCN compounds can be formed using fabrication methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and chemical synthesis. Successful SiCN thin films fabricated with different techniques and their characteristics have been reported extensively in the literature; however, the influence of hydrocarbon gas precursors has not drawn the same amount of attention for SiCN. Chemical, physical, and mechanical properties of thin films are determined by the growth parameters and the choice of sources used, like the organic single-molecule (methylsilazanes) or highly pure individual gas precursors [2,3]. The chemical vapor deposition systems mainly affect the energy of bombarding ions. Plasma-enhanced CVD has been commonly used for thin-film depositions since it provides low deposition temperature, high purity, good step coverage, and easy control of reaction parameters.Our work focuses on the electron-cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVD) method to fabricate SiCN thin films. This method differs from other PECVD methods because it can generate a dense, highly ionized plasma (1011 ions/cm3) and ion impingement energies on the substrate as low as 20 eV [4]. A combination of argon diluted silane (SiH4) and molecular nitrogen (N2) are utilized. For carbon incorporation, we explored the influence of methane (CH4), acetylene (C2H2), and ethane (C2H6) hydrocarbon gas precursors on SiCN thin film properties. The stoichiometry, density of the thin film, optical constants, and the bonding structure of SiCN thin films as a function of hydrocarbon carbon flow rates are presented. Due to the hydrogen-containing precursors used, the silicon carbonitride films deposited by CVD methods contain a significant amount of hydrogen (H), lowest for C2H2 and highest for C2H6. Nearly stoichiometric silicon nitride and silicon carbide thin films were also prepared to interpret the measurements further. From Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analysis, quantitative elemental composition distributions including H were found for films deposited with both carbon sources. For further investigation of the bonding structure of SiCN, Fourier Transform Infrared (FTIR) Spectroscopy was performed. Furthermore, we studied the hardness and Young’s modulus by nanoindentation, and optical constants were measured by variable angle spectroscopic ellipsometry (VASE).[1] C.W. Chen, C.C. Huang, Y.Y. Lin, L.C. Chen, K.H. Chen, W.F. Su, Optical prop- erties and photoconductivity of amorphous silicon carbon nitride thin film and its application for UV detection, Diamond Relat. Mater. 14 (3-7) (2005) 1010–1013.[2] Schwarz-Selinger, T., Von Keudell, A., & Jacob, W. (1999). Plasma chemical vapor deposition of hydrocarbon films: The influence of hydrocarbon source gas on the film properties. Journal of Applied Physics, 86(7), 3988-3996.[3] V.I. Ivashchenko, A.O. Kozak, O.K. Porada, L.A. Ivashchenko, O.K. Sinelnichenko, O.S. Lytvyn, T.V. Tomila, V.J. Malakhov, Characterization of SiCN thin films: experimental and theoretical investigations, Thin Solid Films 569 (2014) 57–63.[4] M. G. Boudreau, "SiOxNy Waveguides Deposited by ECR-PECVD", M.Eng. thesis, McMaster University, 1993.

Advanced microstructure, morphology and CO gas sensor properties of Cu/Ni bilayers at nanoscale

In this study, we investigated the morphology of synthesized Cu/Ni nanoparticles in trace of carbon sources by the co-deposition process of RF sputtering and RF-PECVD methods and localized surface plasmon resonance of CO gas sensing of Cu/Ni nanoparticles. The surface morphology was studied by analyzing 3D micrographs of atomic force microscopy using image processing techniques and fractal/multifractal analyses. The MountainsMap® Premium software with the two-way ANOVA (Variance analysis) and least-significant differences tests were used for statistical analysis. The surface nano-patterns have a local and global particular distribution. Experimental and simulated Rutherford backscattering spectra confirm the quality of nanoparticles. Then, prepared samples were exposed to CO gas flue to study their gas sensor application using the localized surface plasmon resonance method. Increasing the Ni layer over Cu one shows an interesting result in both morphology and gas sensing sides. Advanced stereometric analyses for the surface topography of thin films in conjunction with Rutherford backscattering spectrometry and Spectroscopic analysis make a unique study in the field.

Design and Development of a Chopper for Ion Beam Current Measurement and Monitoring

For the ion beam analysis of insulating materials, we have investigated the design and calibration of an ion beam chopper. The chopper consists of a holder, a chopper plate, four photo sensors, a stepper motor, and an electronic control unit. The chopper plate was designed based on sharing an equal fraction of the ion beam between the chopper and the target. The situation of the chopper to the ion beam is controllable by using four photo-sensors around it. The time intervals in which the material is analyzed and the number of incident ions measured are determined via gate pulses governed by the sensors’ signals. The ion beam current was measured by charge integration at the chopper plate. We calculated the charge correction factors to eliminate the contribution of secondary electrons to the measurements. The measurements were done via Rutherford backscattering spectroscopy (RBS) analysis of a thin Au layer deposited on Si wafer with helium and proton ions in the energy range of 1–2.2 MeV with a precision of less than 5%. The charge correction factors are independent of the ion beam current.

Tunable emission from Eu:SiOxNy thin films prepared by integrated magnetron sputtering and plasma enhanced chemical vapor deposition

This paper reports tunable emission of trivalent (Eu3+) and divalent (Eu2+) europium (Eu) from SiOxNy films fabricated by integrated electron cyclotron plasma enhanced chemical vapor deposition and magnetron sputtering. The photoluminescence (PL) spectra of intense red emission from Eu3+ around 600 nm and blue (cyan) broadband emission from 400 to 750 nm of Eu2+ are observed under daylight conditions with the naked eye. The spectra reveal a strong dependency of the PL on the atomic concentration of the dopant and the silicon/nitrogen ratio. The atomic composition of the films is investigated by Rutherford backscattering spectrometry and elastic recoil detection analysis. Values of the refractive indices are obtained by variable angle spectroscopic ellipsometry. To confirm the presence of crystalline phases of europium silicate Eu4.67(SiO4)3O [Eu2(Si2O7)] and europium silicon oxynitride (EuSi2N2O2) distributed in the amorphous host matrix of SiOxNy, high-resolution x-ray diffraction is used. The findings of this work are promising toward the realization of europium-doped Si-based materials for photonics and lighting technologies.

In1-xGaxSb nanofoams made by ion irradiation of sputtered films: Atomic composition and structure

This article reports on the atomic composition and structural changes induced by ion irradiation in In1-xGaxSb films deposited by magnetron sputtering on SiO2/Si. Samples with x values equal 0, 0.2, 0.4, 0.5 and 1 were irradiated with 16 MeV Au+7 ions, in the fluence range 5 × 1013–2 × 1014 cm−2 (3 × 1014 for GaSb) and the structure and atomic composition of the films were investigated. Upon irradiation, all films attain a nanofoam-like structure, and the most pronounced swelling was observed in ternary films with 20% Ga atomic concentration. With particle induced x-ray emission technique, we identified the presence of C, O, Ga, In and Sb, with C and O concentrations significantly higher in the nanofoams, compared to the as-deposited films. Rutherford backscattering spectrometry analysis showed the atomic composition of the ternaries is not uniform, but forms two layers with slightly different relative atomic concentrations, specially after irradiation, with C and O uptake greatly enhanced by ion irradiation, more pronounced towards the surface. Grazing incidence x-ray diffraction analysis revealed that ion irradiation with total fluence of 2 × 1014 cm−2 induces amorphization of the ternaries, except for samples with 50% Ga, which remain polycrystalline, despite the ion-induced porosity.