Rutherford Backscattering Spectrometry Measurements Research Articles

Multiscale phonon thermal transport in nano-porous silicon

We performed a comprehensive multi-scale phonon-mediated thermal transport study of nano-porous silicon (np-Si) films with average porosities in the range of φ = 30%–70%. This depth-resolved thermal characterization involves a combination of optical methods, including femtosecond laser-based time-domain thermo-reflectance (TDTR) with MHz modulation rates, opto-thermal micro-Raman spectroscopy, and continuum laser wave-based frequency domain thermo-reflectance (FDTR) with kHz modulation rates probing depths of studied samples over 0.5–1.2, 2–3.2, and 23–34 μm, respectively. We revealed a systematic decrease in thermal conductivity (k) with the rise of φ, i.e., with the lowering of the Si crystalline phase volumetric fraction. These data were used to validate our semi-classical phonon Monte Carlo and finite element mesh simulations of heat conduction, taking into account disordered geometry configurations with various φ and pore size, as well as laser-induced temperature distributions, respectively. At high φ, the decrease in k is additionally influenced by the disordering of the crystal structure, as evidenced by the near-surface sensitive TDTR and Rutherford backscattering spectroscopy measurements. Importantly, the k values measured by FDTR over larger depths inside np-Si were found to be anisotropic and lower than those detected by the near-surface sensitive TDTR and Raman thermal probes. This finding is supported by the cross-sectional scanning electron microscopy image indicating enhanced φ distribution over these micrometer-scale probed depths. Our study opens an avenue for nano-to-micrometer scale thermal depth profiling of porous semiconducting media with inhomogeneous porosity distributions applicable for efficient thermoelectric and thermal management.

Co-deposition of bismuth-nitrogen films on MgO (001) by molecular beam epitaxy

We attempted to grow a thin film of BiN by co-deposition of bismuth and nitrogen on rock-salt structure MgO (001) substrates. Furthermore, we studied the effect of variation of the growth temperature and the nitrogen to bismuth flux ratios on sample growth. For the samples grown and conditions used, we do not find strong evidence for the formation of a bulk Bi-N alloy. Even for very high nitrogen to bismuth flux ratio, we observed only bismuth and no nitrogen using bulk Rutherford back-scattering spectroscopy measurements, and only 1%–2% nitrogen was seen through surface Auger electron spectroscopy measurements. The in-plane lattice measurements show that the resulting Bi (110) samples are strained, which is presumably caused by lattice mismatch between the sample and the substrate when grown without any buffer layer. The use of a high-temperature buffer layer helps to release strain in the sample but only along one axis. Measurements of the atomic layer spacing using x-ray diffraction and also scanning tunneling microscopy confirm the Bi (110) thin film sample structure.

Pathway to high performance, low temperature thin-film solid oxide cells grown on porous anodised aluminium oxide

Reversible solid oxide cells (rSOCs) present a promising solution to future energy challenges through the efficient conversion between electrical and chemical energy. To date, the benefits of rSOC technology have been off-limits to portable power and electrolysis applications due to the excessive polarisation resistance of the oxygen electrode at low temperatures, characterised by high area specific resistance (ASR) values below 500 °C. In this work we demonstrate growth of symmetric and complete rSOC structures based on state-of-the-art vertically aligned nanocomposite (VAN) films grown by pulsed laser deposition (PLD) on porous Pt-coated anodised aluminium oxide (AAO) substrates. The symmetric rSOC structures give the first demonstration of an rSOC oxygen electrode with ASR below 0.1 Ωcm2 at temperatures less than 450 °C. This is achieved through oxygen vacancy tuning by annealing, as confirmed by Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) and Rutherford Backscattering Spectrometry (RBS) measurements. Thus, the present work describes a promising route towards future high-performance rSOC devices for portable power applications.

Mechanism of Electrochemical Oxidation of Titanium Via Isotopic Labeling, Medium Energy Ion Scattering, Nuclear Reaction Profiling, in-Situ Rutherford Backscattering Spectrometry, and Electrochemical Impedance Spectroscopy

The few nanometres of titanium oxide present on titanium and Ti alloy surfaces are responsible for protecting the underlying metal from oxidation and enabling its use in many high-performance applications. The oxide provides a hard, uniform, and thermodynamically stable protective coating on an otherwise soft and very reactive metal. Because of its passivating oxide film, titanium has found uses in biomedical implants, aerospace engineering, corrosive industrial piping, and other areas where high strength and low weight are required.Our project is aimed at understanding the atomistic mechanisms of TiO2 formation and growth. We have taken several different approaches to investigate the details of this process. In one approach, the electrochemical oxidation mechanism of titanium at applied potentials between 0 and 10 V vs the saturated calomel reference electrode (SCE) was examined for ultra-thin Ti films sputtered onto Si(001) substrates and exposed in-situ to H2 18O, and then anodized in D2 16O. The effects of this isotopic labeling procedure were studied using medium energy ion scattering (MEIS) and nuclear reaction profiling (NRP). Both MEIS and NRP results are consistent in showing that the titanium oxide layer is composed of two distinct regions (Ti16O2/Ti18O2/Ti/Si) for the entire range of the formation voltages (0–10 V vs SCE). The oxygen component of the outermost region consists entirely of 16O, and the 18O region is always adjacent to the Ti metal. No Ti or 18O loss into the electrolyte solution during anodization was detected. The oxide thickened linearly as a function of potential in the 0–10 V range vs SCE, with experimental anodization ratio of 24.5±0.6 Å V−1. Mott–Schottky (MS) analyses showed positive slopes, indicating formation of an n-type TiO2 semiconductor, with O vacancies (or Ti interstitials) as major charge carriers in the 0–10 V range. Charge carrier densities, ND = (0.8-5.0)×1021 cm−3 were calculated from Mott–Schottky analysis and were well within the range of results reported in the literature. We observed a decrease in the charge carrier densities above ∼4 V vs SCE, that can be connected to defect annihilation or minor modification in the structure (electrostatic annealing) of the growing TiO2 film.In a second approach, we are using Rutherford backscattering spectrometry (RBS) for elemental depth profiling during oxide growth to determine oxidation rates and the role of the anodization potential on the Ti oxide layer structure and morphology. RBS is a powerful ion beam-based analytical tool used to determine thickness at the nanometer scale and elemental depth distribution, making it an excellent choice for studying the thin oxide on titanium. A difficulty with using RBS for such studies has been that RBS must function under ultra-high vacuum, and this has made it incompatible with performing aqueous electrochemistry; therefore, RBS had to be performed as an ex situ analysis, like MEIS and NRP. We are overcoming this limitation by using a specially designed in-situ cell with an ion-permeable silicon nitride window to provide a barrier between the ultra-high vacuum (UHV) required to perform RBS and the aqueous electrolyte solution required for anodization. In this cell, the thin silicon nitride window is coated with titanium and functions as the working electrode when exposed to the aqueous electrolyte solution. RBS measurements are taken as the titanium metal is anodized to titanium oxide. RBS is then performed during in-situ anodization, to obtain information about the growth mechanism of titanium oxide. Our initial in-situ RBS results show a significant increase in the oxidation rate of titanium compared to equivalent ex-situ measurements, and we also observe spontaneous TiO2 film growth without applying an anodic polarization. These effects are likely generated by strongly oxidizing water radiolysis products (e.g., H2O2 or ·OH) formed by the action of high-energy He+ ions interacting with the electrolyte solution.This paper discusses our experimental methods and presents an overview of the results and conclusions of this work.

Effect of tin concentration on the morphological & crystal structure, and optical properties of chemical vapor deposited MAPb1−xSnxI3 perovskite films for 0 ≤ x < 0.5

In this article, we evaluate the impact of Sn proportion on the morphology and crystal structure, and its influence on the optical properties of MAPb1−xSnxI3 (0 ≤ x < 0.5) perovskite films. The uniform and compact Sn-Pb halide films with a variety of grain sizes were deposited using a low-pressure chemical vapor deposition (LP-CVD) system and were sequentially converted into perovskite films. Rutherford backscattering spectrometry (RBS) measurements were performed to determine the depth profile of elements and the simulated spectra suggested multilayered films. The x-ray diffraction (XRD) patterns confirmed the formation of the perovskite phase, i.e. tetragonal structure with I4cm space group. The energy bandgap (Eg) and the Urbach energy (Eu) approximation insinuate a tradeoff between the attainment of low bandgap Sn-Pb halide perovskites and defect-disorder tolerant films.

Modelling the strain build-up in nitrogen implanted tungsten films on silicon substrates

A model of the strain accumulation in nitrogen implanted polycrystalline tungsten films deposited on 110 single-crystalline silicon substrates is presented. The films, with the nominal thickness of 500 nm, were implanted at room temperature, in a direction perpendicular to the sample surface with an energy of 60 keV N2+ ions and concentrations between 0.5 × 1017/cm2 and 5 × 1017/cm2. The proposed model is based on the simulations of the X-ray diffraction 2θ-ω scans in the vicinities of the 110 W most intense Bragg peak. Up to a fluence of 2 × 1017/cm2, the increase of asymmetry towards lower angles of the 110 W peak is interpreted as a linear increase in strain affecting the entire implanted region. Then, the solubility of N in W saturates and phase transition to fcc β-W2N is observed. The phase transition occurs at the surface strain regions of the implanted crystal volume while the lowest strained regions are masked by the β-W2N barrier and even evidence some relaxation. After 3 × 1017/cm2, the strain deduced for the 111 and 200 planes of the fcc β-W2N formed pseudo-layer increases at different rates. While the former comprises a maximum tensile deformation of 3.8 %, the latter is more resilient to nitrogen irradiation developing less than half of the strain magnitude (1.5 %). After 4 × 1017/cm2, Rutherford backscattering spectrometry measurements suggest partial sputtered N while X-ray diffraction indicates no strain-relief at the remaining surface fcc β-W2N. The N concentration derived by the ion beam technique and the combined 110 W/ (111, 200) β-W2N strain profiles as functions of depth agree with the Simulations of Ions and Radiation in Matter theoretical predictions.

Photoluminescence from InSb1−xBix alloys at extended wavelengths on InSb

The incorporation of dilute concentrations of bismuth into traditional III–V alloys produces significant reductions in bandgap energy presenting unique opportunities in strain and bandgap engineering. However, the disparity between the ideal growth conditions for the host matrix and those required for substitutional bismuth incorporation has caused the material quality of these III–V–Bi alloys to lag behind that of conventional III–V semiconductors. InSb1−xBix, while experimentally underexplored, is a promising candidate for high-quality III–V–Bi alloys due to the relatively similar ideal growth temperatures for InSb and III–Bi materials. By identifying a highly kinetically limited growth regime, we demonstrate the growth of high-quality InSb1−xBix by molecular beam epitaxy. X-ray diffraction and Rutherford backscattering spectrometry (RBS) measurements of the alloy's bismuth concentration, coupled with smooth surface morphologies as measured by atomic force microscopy, suggest unity-sticking bismuth incorporation for a range of bismuth concentrations from 0.8% to 1.5% as measured by RBS. In addition, the first photoluminescence was observed from InSb1−xBix and demonstrated wavelength extension up to 7.6 μm at 230 K, with a bismuth-induced bandgap reduction of ∼29 meV/% Bi. Furthermore, we report the temperature dependence of the bandgap of InSb1−xBix and observed behavior consistent with that of a traditional III–V alloy. The results presented highlight the potential of InSb1−xBix as an alternative emerging candidate for accessing the longwave-infrared.

Ni-Au layers on sapphire prepared by direct current magnetron sputtering

Thin bimetallic Ni-Au layers (∼100 nm) with three different Au content were prepared by direct current magnetron sputtering onto sapphire substrates. The elemental composition and the layer thickness of bimetallic layers were controlled during the sputtering process. The prepared Ni-Au layers were annealed at temperatures of 400°C and 900°C in the air to determine the behavior of Au and Ni in the layers after heating. The elemental composition and depth profiling was provided by Rutherford backscattering spectrometry (RBS). The surface morphology was examined via Scanning electron microscopy (SEM). RBS measurement revealed inter-diffusion Au into sapphire substrate after thermal annealing and the formation of grains and voids.

Stabilization of nanoscale iron films by self-terminated electrodeposition in sulfate electrolyte

Iron and iron oxide nanostructures are of broad interest for numerous applications, such as in the fields of magnetic data storage, spintronics, biosensing and catalysis. In all of these cases, defined deposition on nanometer scale is essential for functionality. For conventional electrodeposition of transition metals, precise thickness control and layer stability at the nanoscale are difficult due to dissolution tendencies in acidic electrolytes after the voltage is switched off. In contrast to previous studies that focused on self-termination of Ni and Ni-based alloys, we investigate the thickness control of nanoscale iron oxide/iron layers using self-terminated electrodeposition from sulfate electrolytes. Electrochemical quartz crystal microbalance measurements show that self-terminated thickness can be controlled by both deposition potential and iron ion concentration. Comparison of experimental results with model calculations based on diffusion theory reveal two different growth modes for self-termination. At low iron ion concentration, self-termination of iron proceeds via the formation of an ultrathin iron hydroxide layer. At larger iron ion concentration, precipitation of bulk Fe(OH)2 dominates the film growth and self-termination is shifted to more negative potentials. All self-terminated layers exhibit enhanced stability in the electrolyte after the voltage is switched off compared to those deposited in the conventional deposition regime. With in situ Rutherford backscattering spectrometry measurements, we can follow the self-terminating deposition and the stability after voltage switch-off for longer times online. Surface analytical and morphological analyses show that the self-terminated layers exhibit a higher iron oxide/iron ratio and are smoother than layers obtained by conventional electrodeposition.

Coexistence of soft and hard magnetic phases in single layer amorphous Tb–Co thin films

Amorphous, ferrimagnetic Tb–Co thin films prepared with a thin Ta underlayer and either a Ta or a Pt overlayer show evidence of both soft and hard magnetic phases. At room temperature, the films exhibit conventional ferromagnetism, but low temperature magnetometry measurements reveal the decoupling of the two magnetic phases with decreasing temperature due to increased anisotropy energy of the hard layer at lower temperatures. Decreasing the film thickness to 2 nm, slightly above the superparamagnetic limit found at 1 nm, a soft, low-density phase was isolated and found to be present in all the films as confirmed with x-ray reflectivity and Rutherford backscattering spectrometry measurements. For greater thicknesses, the bottom layer retains its soft magnetic nature, while the remainder of the film is denser and has strong perpendicular magnetic anisotropy, leading to the exchange-spring behavior when the anisotropy becomes large, either at low temperatures or via a Pt overlayer that adds a strong interfacial anisotropy to the layer. Micromagnetic simulations of a soft/hard bilayer model with the experimentally determined anisotropy and magnetization parameters into a soft/hard bilayer model reproduced the experimental hysteretic behavior very well. These findings demonstrate how the magnetic state and the response of a-Tb–Co films to external fields can be controlled, providing a high degree of tunability that is promising for high-performance nanoscale devices.

On the Adhesion of Protein in Nitrided Metallic Coatings for Electrosurgical Electrodes of Stainless Steel

In this study, it is investigated the anti-adhesive effectiveness of ZrN/Ti and TiN/Ti, deposited by magnetron sputtering, as coating materials of electrosurgical electrodes of steel in protein adhesion tests. Stoichiometry and the thickness of the systems were assessed with Rutherford backscattering spectrometry measurements. Vertical surface deviations were evaluated with the five-point mean height and the arithmetic average height and correlations between the amount of adhered protein in the electrosurgical electrodes and measurements of wettability and electrical resistivity were investigated. The quality of both coatings was put to the test through protein adhesion tests at high temperatures. Cuts with electrosurgical electrodes were performed in an abdominal flap for different electric power and cutting times. The results indicate less adhesion of protein on both proposed coatings, compared to the traditional electrodes of stainless steel, proving to be cheaper alternatives for the surgical industry than other massive anti-adherent electrodes as Au and Ti.

Determination of the composition and thickness of chromel and alumel thin films on different substrates by quantitative energy dispersive spectroscopy analysis.

Thin films of two alloys (chromel and alumel), with thickness less than 100 nm, were obtained by plasma deposition technique, namely filtered cathodic vacuum arc (FCVA). The elemental analyses were performed by quantitative energy dispersive spectroscopy (EDS) microanalysis and Rutherford backscattering spectrometry (RBS). The applicability of EDS to such thin films as these was established by analysis of films deposited on substrates of different atomic numbers, specifically vitreous carbon, silicon, copper, and tin. We found that a substrate with atomic number similar to the mean atomic number of the film constituents is best for reliable EDS results, when compared to RBS. The compatibility between quantitative EDS measurements and RBS measurements, as well as comparison between the thin film elemental composition and the bulk material composition, was assessed by statistical analysis. Good consistency between EDS and RBS measurements was found for both chromel and alumel thin films when copper was used as substrate material. We observed severely overlapping peaks in the RBS output for the case of alumel films so that EDS analysis was crucial. We also compared thickness measurements determined by EDS and RBS, and we found good agreement for the case of alumel film on copper substrate, and 15% agreement for chromel film on copper substrate.

Sensitive in-operando observation of Li and O transport in thin-film Li-ion batteries

Thin-film batteries often contain oxides in the anode, cathode, and electrolyte materials. In-operando methods capable of Li and O depth profiling are relevant for battery research to study, e.g. diffusion and trapping of constituents. Here, we demonstrate ion beam–based analytical methods with high depth resolution and sensitivity for depth profiling Li and O in thin-film batteries using 10 MeV Li and He ions. Simultaneous depth profiling of Li and O was performed using combined coincidence elastic recoil detection analysis and Rutherford backscattering spectrometry measurements in the battery with 8 MeV He ions, and the Li and O transport was measured in operando. Reversible Li transport was observed from the LMO anode to the NbO cathode on charging and vice versa during discharging. O transport was observed from the LMO anode to the NbO cathode on first charging with 3.5 V but was not observed on further charging and discharging of the battery. Our in-operando measurements allow direct and quantitative observation of Li and O transport during charge-discharge cycles for thin-film batteries.

The energy calibration of the IFIN-HH 3 MV Tandetron accelerator for alpha particles

Ion accelerators have a fundamental role in atomic and nuclear studies as well as in applied physics, including the modification and characterization of materials. The precise knowledge of the energy of accelerated ions is of utmost importance, especially for cross-section measurements or for accurate depth profiling using narrow resonances. The 3 MV Cockcroft–Walton tandem accelerator of IFIN-HH from HVEC was installed in 2012. The machine is mainly dedicated to ion beam analysis, ion implantation, and astrophysics studies at low energy. In this work, we report on the first calibration for alpha particles of the terminal voltage using a technique based on Rutherford backscattering spectrometry measurements. The energies of the α particles from a mixed spectroscopic 239Pu + 241Am α source are compared with the energies of 4He projectiles backscattered into a silicon detector by carbon and gold layers. The position of the 16O(α,α) 16O resonance around 3.038 MeV at backscattering angles of 145° and 165° was remeasured. Our results are compared with recent results reported in the literature.

Growth of low resistive nickel mono-silicide phase under low energy Si ion irradiation at room temperature

Nickel mono-silicide (NiSi) is considered as a promising material for developing low resistance contacts in complementary metal-oxide-semiconductor technology. In the present work, we report the effect of Ni film thickness on orientation control of low resistive Nickel mono-silicide (NiSi) phase formation using low energy ion irradiation at room temperature. In order to study the effect of Ni film thickness on NiSi phase formation, the Ni films of thicknesses 30 nm and 60 nm were deposited on Si (111) substrate using thermal evaporation technique in a high vacuum chamber. The as prepared Ni/Si samples were then irradiated via 120 keV Si ions with different fluences of 7 × 1014, 1 × 1015, 3 × 1015 and 7 × 1015 ions-cm−2 at room temperature. The x-ray diffraction and transmission electron microscopy measurements clearly confirm the formation of mono-silicide phase. The composition of the NiSi phase is determined by Rutherford backscattering spectrometry measurements. The crystallinity of NiSi phase has been observed to be better for 60 nm Ni film as compared to the 30 nm Ni film on Si substrate. Most of the NiSi crystallites are found to be oriented in (103) lattice plane. The resistivity and sheet resistance of the NiSi/Si films are found to be very low. The role of composition of Ni and Si in NiSi phase on resistivity and sheet resistance of the films has been investigated carefully. The detailed mechanisms behind the above observations have been discussed in the paper.

Impact of oxygen vacancies to control the magnetic and electronic properties of the La2CoMnO6 system

The pervoskite oxygen vacancies have been accepted as essential functional defects and are effective in regulating their multifunctional properties. The bulk sample La2CoMnO6 (LCMO) was prepared by solid state routing and the film La2CoMnO6 by plus laser deposition (PLD). The samples phase purity was verified by means of X-ray diffraction measurement. It has been established from the core level of X-ray photoelectron spectroscopy that the concentration of Mn3+ ions increases, impairs the double exchange between Mn3+ and Mn4+ and thus leads to the degraded magnetic properties. A source of synchrotron radiation is used to analyze the valence band spectroscopy measurements from which, mainly as a result of oxygen vacancies, a huge change in the density of states (DOS) are observed near the Fermi level (EF). Such findings are related to records of resistivity and magnetization. Rutherford backscattering spectrometry (RBS) measurements were made using 2 MeV He2+ ions on the LCMO film and information regarding film thickness was extracted. These findings indicate that a dip in DOS at Fermi-level has slowed LCMO film conduction. It can be a result of changes in orbital hybridization due to oxygen vacancies that modify the octahedra of MnO6.

Molybdenum Oxide Thin Films Grown on Flexible ITO-Coated PET Substrates.

Molybdenum oxide thin films were deposited on stiff and flexible substrates by reactive DC magnetron sputtering. Two sets of samples were prepared. The first with different O2/Ar flow rate ratios and the second, fixing the oxygen content, with different time of deposition. As the O2/Ar flow rate ratio varies from 0 up to 0.56, a threshold was found, ranging from crystalline to amorphous nature, and from a nontransparent appearance with metallic-like electrical conductivity to transparent and dielectric behaviour. From the second set, all transparent, the MoOx films present a compact/dense and featureless morphology with thickness from 190 up to 910 nm, depending on the time of deposition. Their structure was corroborated by XPS and Rutherford Backscattering Spectrometry (RBS) and density measurements were performed by RBS and X-ray reflectivity (XRR), revealing a value of 2.4 g/cm3. The surface roughness is in the order of a few nanometers and the maxima optical transmission, in the visible range, is around 89%. Electrochemical cyclic voltammograms showed noticeable color reversibility and reproducibility on the flexible substrates opening new framework possibilities for new electrochomic devices.

Atomic layer deposition of hafnium and zirconium oxyfluoride thin films

Hafnium and zirconium oxyfluoride films may act as effective protective coatings during plasma processing. The low molar volume expansion/contraction ratios and the small estimated strain values versus fluorination/oxidation suggest that hafnium and zirconium oxyfluorides can serve as protective coatings in both fluorine and oxygen plasma environments. To demonstrate the procedures for depositing these films, hafnium and zirconium oxyfluorides with tunable stoichiometry were grown using atomic layer deposition (ALD) at 150 °C. Tetrakis(dimethylamido)hafnium and tetrakis(ethylmethylamido)zirconium were used as the metal precursors. H2O and HF were employed as the oxygen and fluorine precursors, respectively. MOxFy (M = Hf and Zr) films were grown using two deposition mechanisms: the nanolaminate method and the HF exchange method. In situ quartz crystal microbalance studies were employed to monitor the MOxFy growth. Both deposition methods observed a linear MOxFy growth at 150 °C. The nanolaminate method is defined by the sequential deposition of MOx ALD and MFy ALD layers. Compositional tunability was achieved by varying the ratio of the number of MOx ALD cycles to the number of MFy ALD cycles in the nanolaminate. The HF exchange method is based on the thermodynamically favorable fluorination reaction of MOx by HF. Variable oxygen-to-fluorine concentrations in these films were obtained either by changing the HF pressure or by varying the thickness of the underlying MOx ALD layers. Ex situ Rutherford backscattering spectroscopy measurements were utilized to determine the composition of the various MOxFy thin films. Both deposition techniques displayed a wide range of compositional tunability from HfO2 to HfF4 and ZrO2 to ZrF4. In addition, the physical sputtering rates of MOxFy films were estimated from the film removal rates during ex situ x-ray photoelectron spectroscopy depth profiling. The physical sputtering rates increased with F concentration in the MOxFy films.

Does substrate colour affect the visual appearance of gilded medieval sculptures? Part II: SEM\u2013EDX observations on gold leaf samples taken from medieval wooden sculptures

In the previous paper (Part I), the colorimetry and interferometric microscopy measurements on modern gold leaf models have revealed that the visual appearance of a gilded surface, both burnished and unburnished, depends strongly on the substrate type, surface roughness and texture, but not on the colour of the substrate. In this second part, we investigate the materials compositions and technical specifications of medieval gold leaf through combining literature sources and materials analysis such as scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM–EDX) on samples taken from gilded wooden sculptures. Our study shows that the late medieval gold leaf has a high purity of about 23.7 carat and has an average thickness of 160 nm (with a peak value of 138 nm), purer and thicker than the modern gold leaves studies in Part I. Supportive Rutherford backscattering spectrometry (RBS) measurements on gilded models confirms the accuracy and reliability of the SEM–EDX observations on the medieval gold leaf samples. We additionally present observations of a rarely recorded special variant of medieval gold leaf—“fine reinforced gold leaf”. Combined with the findings from Part I, we conclude that light penetrating the medieval gold leaf and reflected from the gilding substrate could not be a significant, or even perceptible contribution to the visual appearance of the gilding. We argue that the misconception surrounding the correlation between the substrate colour and the gilded surface appearance can be attributed to the historical development of gilding and polychromy technologies.

Europium Doped Silicon Oxide Thin Films Using an Integrated PECVD and Sputtering System

Over the last decades, silicon-based materials have exhibited outstanding electronic properties and been used in photovoltaic and electrical devices such as transistors [1]. However, due to their indirect band gap nature and poor light emitting properties, they are not satisfying candidates when it comes to photonics. One way through which this poor performance is sorted out is doping of rare earth (RE) elements into the silicon nanostructure thin film to enhance the light emission. The reason for the use of RE elements in silicon-based materials is the fact that they showed well-defined emission peaks and 4f electron shielding making them independence of the host matrix [2].In this study, luminescence properties of Europium (Eu) doped oxygen rich silicon oxide (ORSO) materials using two fabrication techniques are discussed as well as controlling of the Eu concentration, argon partial pressure and sputtering power. In addition, the effect of different annealing atmospheres is observed as here pure nitrogen (N2) and forming gas (N2+5% H2) are tested at a variety of deposition temperatures ranging between 300 °C and 1350 °C. In particular, samples subjected to the higher annealing temperatures of 1200 °C and 1350 °C behave differently in comparison with lower annealing temperatures where their structural and photoluminescence (PL) properties are investigated in more details.The introducing of Eu into ORSO host matrix was performed by two different deposition methods with the first one being the conventional method of metal organic powders where RE elements are introduced using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) system. The second method involves the use of a novel and custom-made integration of ECR-PECVD and magnetron sputtering [3]. The investigation of a variation of optical and structural properties of the samples made with similar deposition parameters using these two different techniques resulted in insignificant light emission of the ones fabricated with metal organic precursor and remarkable emission of the samples produced using the integrated ECR-PECVD and sputtering method.Variable angle spectroscopic ellipsometry (VASE) measurements are carried to comprehend the refractive index and thin films thicknesses, and their dependence on the deposition parameters such as the sputtering power. Rutherford backscattering spectrometry (RBS) measurements provide the film composition and verify a good control of the Eu concentration using the second deposition method (integrated ECR-PECVD and sputtering). X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) confirm the formation of nanostructures in the Eu-ORSO thin films following post-deposition annealing beyond 1200 °C. The PL studies are performed to study the light emission properties of Eu-ORSO thin films and the changes introduced by the hydrogen passivation. Figure 1 shows the influence of hydrogen passivation on one of the Eu-ORSO thin films containing 0.1 ± 0.01 at. % of Eu. The sample is annealed at 1200 °C and 1350 °C using N2 and N2+H2 atmospheres for 1 hour in the quartz tube furnace. The hydrogen passivation enhances the PL emission by one order of magnitude possibly due to the passivation of the defects and dangling bonds.