RBS Measurements Research Articles

Observation of dielectric anomaly at magnetic transition temperature in NdMn1xZnxO3/SNTO (x = 0.00, 0.05, 0.10) films

We report our observation of dielectric anomaly from temperature–dependent dielectric study near the antiferromagnetic transition (TN) in pure and Zn–doped NdMnO3/SNTO (SrNb0.002Ti0.998O3) epitaxial films. Structural and microstructural studies showed the presence of compressive strain along the a–axis and changes in grain size due to Zn–substitution. The variation in the elemental concentration of Zn was confirmed by RBS measurements led to amend Mn–Mn exchange interactions in doped films. Alteration in TN due to Zn–doping, obtained from D.C. magnetization is consistent with the dielectric anomaly temperatures, indicating the presence of magnetoelectric effect in pure and Zn–doped NdMnO3/SNTO system.

Situational Analysis of Selected NCDs-Type 2 Diabetes Mellitus and Hypertension among PLHIV Attending ART Center of Tertiary Care Hospital in India: A Mixed Methods Study.

Antiretroviral therapy (ART) has transformed the life of PLHIV with a longer life expectancy. The rising coexistence of non-communicable diseases (NCD)s especially type 2 diabetes mellitus (DM) and hypertension (HTN) among PLHIV (people living with HIV) is much more complicated and demanding for the health system, patients, and their families. To document the current status of type 2 DM and HTN among known diabetic/hypertensive PLHIV attending ART center, tertiary care hospital of South Gujarat. A mixed method study (cross-sectional survey followed by qualitative in-depth interview) was conducted among 184 PLHIV on ART with history of Type 2 DM and/or Hypertension who were registered and availing services from ART center, tertiary care hospital. Convenient sampling technique was used. All the participants were interviewed using pre-designed, semi-structured questionnaire, during their routine visits. In -depth interview (IDI) has been conducted to explore the delivery of NCD services at ART Centre. Out of 184 PLHIV on ART, the most common co-morbidities were Type 2 DM (46.2%), HTN (39.13%), and 14.67% had both. Among total 184 participants, 64.1% were males and 35.9% were females. Only 22.3% of participants were availing treatment services for the above at tertiary care hospital. The study results showed a range of findings involving ART adherence, BMI, RBS, and BP measurements were included. IDI results described the NCD service delivery at ART Center. Study results suggest that the services received by PLHIV with NCD require an overhauling. Routine monitoring and strengthening of existing services should be focused to upgrade the quality and continuum of the care provided to PLHIV with NCD.

ANTIMICROBIAL SENSITIVITY PATTERN OF PEDIATRIC CYSTIC FIBROSIS PATIENTS IN PAKISTAN

Cystic fibrosis (CF) is a complex genetic disorder affecting the respiratory and digestive systems, causing recurrent infections. This study aimed to evaluate the microbiological cultures and identify the patterns of antimicrobial sensitivity among young CF patients in Pakistan. This prospective observational study was conducted at the Pakistan Institute of Medical Sciences (PIMS) from December 2021 to November 2022, involving comprehensive assessments, interviews, clinical tests, MTs, CBCs, CXRs, sputum cultures, RBS measurements, microbiological analysis of sputum and oropharyngeal swabs, antimicrobial susceptibility testing, and statistical analyses (p ≤ 0.05) using SPSS for both continuous and categorized data. Pseudomonas Aeruginosa was the most common respiratory pathogen (n=21; 36%), and most CF-afflicted children (n=46; 77.96%) had infections with a single microorganism. Significant associations (p < 0.05) were observed between Streptococcus pneumoniae, Klebsiella Pneumoniae, Staphylococcus Aureus, and Acinetobacter with their antibiotic sensitivity patterns. In contrast, Pseudomonas Aeruginosa and Escherichia Coli showed no statistically significant associations. Ciprofloxacin demonstrated high sensitivity, followed by Levofloxacin, while several first-generation antibiotics, including rifampicin, erythromycin, and amoxicillin, exhibited nearly complete resistance against bacteria collected from children with CF. Ciprofloxacin and Levofloxacin emerge as the foremost effective therapeutic agents for CF patients, advocating the perpetual promotion of active surveillance to monitor resistance patterns.

Depth profile analysis of 100 keV Ni ions in Si 〈100〉 substrate

Nickel implanted silicon substrate shows potential applications for the fabrication of infrared detectors, solar cells, spintronic devices as well as for the synthesis of an embedded nickel silicide layer inside Si substrates. Emerging applications of the transition metal implanted silicon structures for the fabrication of intermediate band materials motivated us to study the in-depth distribution profile of Ni ions as well as the structural changes that occur at the top of silicon substrate surface before and after annealing process. In the present work, we have carried out detailed study on the crystalline silicon substrates, implanted with Ni− ions comprising ion dose value of 5 × 1016 ions/cm2 at 100 keV implantation energy followed with the post implantation annealing at 800 °C temperature for a time duration of 2 h. The distribution profile of nickel ions inside the silicon substrate was estimated using the non-destructive simultaneous XRR-GIXRF measurements and were also compared with results obtained from the RBS and SIMS measurements. The in-depth concentration profile of Ni ions inside Si substrate derived from XRR-GIXRF measurements was found to be in close agreement with that of obtained from the RBS measurements. Furthermore, our investigations clearly showed that the annealing process causes the inward and outward diffusion of the Ni atoms inside the Si substrate, thus significantly changing the in-depth concentration profile of Ni ions in the Si matrix. The XANES and EXAFS results also demonstrate the formation of NiSi2 phase around Ni atoms in the implanted region of Si 〈100〉 substrate.

Piezo-ferroelectric response of bismuth ferrite based thin films and their related photo/piezocatalytic performance

Bismuth ferrite based thin films were grown by RF magnetron sputtering under different experimental conditions. The effects of substrate temperature, Ar:O2 mass flow ratio and gas mixture pressure on the films’ microstructure, phase evolution, optic, ferroelectric and magnetic properties were systematically investigated. The structural analysis results revealed an amorphous phase for the films deposited at a substrate temperature below 500 °C, while for the thin films deposited at 700 °C, a ε-Fe2O3 secondary phase was detected. The diffraction lines of the samples deposited at 600 °C were associated with Bi2Fe4O9 and Bi25FeO40 phases. The increase in the mixture gas pressure up to 1 Pa showed an improved crystallinity of the deposited films, while, at higher working gas pressures, the films were found to be amorphous. The use of low O2 to Ar mass flow ratio during the deposition led to a phase transformation process. EDX and RBS measurements exposed a uniform distribution of the main elements, revealing some stoichiometry changes induced by the pressure variation. The optical band gap values were influenced by the substrate temperature and pressure of the Ar:O2 gas. The magnetic properties were correlated with the structural features, the highest magnetic response being observed for the sample deposited at 600 °C, 1 Pa and 3:1 Ar:O2 gas pressure. According to the PFM results, the film deposited at 700 °C, Ar:O2 ratio 3:1 and total gas pressure 1 Pa clearly outperformed the others due to their excellent ferroelectric properties and outstanding piezo-response. The sample deposited at 700 °C showed both visible light-driven degradation and piezodegradation activities. The piezocatalytic and photocatalytic activities were ascribed to the high piezoresponse and to a more efficient separation of electrons and holes induced by a built-in electric field that is caused by the larger remnant polarization of Bi2Fe4O9 and Bi2Fe4O9/ε-Fe2O3 hetero-junction.

Homogeneity and Thermal Stability of Sputtered Al0.7Sc0.3N Thin Films

This work presents a study on the homogeneity and thermal stability of Al0.7Sc0.3N films sputtered from Al-Sc segmented targets. The films are sputtered on Si substrates to assess their structural properties and on SiO2/Mo-based stacked acoustic mirrors to derive their piezoelectric activity from the frequency response of acoustic resonators. Post-deposition annealing at temperatures up to 700 °C in a vacuum are carried out to test the stability of the Al0.7Sc0.3N films and their suitability to operate at high temperatures. Despite the relatively constant radial composition of the films revealed from RBS measurements, a severe inhomogeneity in the piezoelectric activity is observed across the wafer, with significantly poorer activity in the central zone. RBS combined with NRA analysis shows that the zones of lower piezoelectric activity are likely to show higher surface oxygen adsorption, which is attributed to higher ion bombardment during the deposition process, leading to films with poorer crystalline structures. AFM analysis reveals that the worsening of the material properties in the central area is also accompanied by an increased roughness. XRD analysis also supports this hypothesis, even suggesting the possibility of a ScN non-piezoelectric phase coexisting with the AlScN piezoelectric phase. Thermal treatments do not result in great improvements in terms of piezoelectric activity and crystalline structure.

Laterally controlled ultra-low energy ion implantation using electrostatic masking

We describe the ongoing development of an ultra-low energy (ULE) ion implantation system for the implementation of a laterally controlled ion incorporation into 2D materials like graphene or transition metal dichalcogenides (TMDs). For this purpose, we use ion optics simulations to demonstrate how the generation of an electrostatic potential gradient laterally along the sample surface can be used to control the size of the implanted sample area. The simulations are complemented by experiments on the incorporation of 25eV Mn ions into thin tetrahedral amorphous carbon (ta-C) films on Si substrates. With the help of RBS measurements, it is shown how potential gradients of different strengths influence the amount of introduced Mn.

Sputter hot filament hollow cathode ion source and its application to ultra-low energy ion implantation in 2D materials

We describe the design of a new ion source that combines a hot filament hollow cathode source with a sputtering source. This combination makes it possible to provide ion beams of a wider range that previously could not be used due to respective high melting points and low vapor pressure of the needed elements. We demonstrate the sources viability for molybdenum, cobalt, niobium and the rare-earth element gadolinium. An implantation current of 20–900nA on the sample, depending on the element, could be achieved. Moreover, we experimentally prove that these ion beams are suitable for ultra-low energy implantation into 2D materials like graphene and transition metal dichalcogenides (TMDs). Furthermore, computational studies were conducted to investigate the ion trajectories within the source and ion implantation into 2D materials. RBS and PIXE measurements were performed to quantitative investigate the implanted samples.

A Novel Bi-Functional Catalyst, Na-Bi-Ru-O, for Oxygen Reactions at Two or Three Phase Boundaries with Alkaline Media

Low carbon technology requires highly efficient energy conversion materials and systems which include the catalyst, the electrode, the separator, and etc. for uses in electrolytic hydrogen production (EHP) and air rechargeable batteries (ARB) linked to solar and wind power generation. One of the important materials is the oxygen catalyst working for OER and/or ORR at the anode of EHP and the positive electrode of ARB, and it has been reported a variety of materials including metals, alloys, oxides, sulfides, doped and un-doped carbon, and others [1-3]. We have been also developing pyrochlore oxides, general formula A2B2O7, containing bismuth at the A-site and ruthenium at the B-site especially for aqueous ARBs, e.g., metal hydride/air and zinc/air batteries, and recently have found that a novel oxide catalyst similar to bismuth ruthenium oxide (BRO) except that sodium is also the component and is highly active for OER and ORR with low Tafel slopes. This paper introduces the pyrochlore-like oxide containing sodium, bismuth, and ruthenium with the preparation process and the results on characterization and electrochemical properties for oxygen reactions of the obtained NBRO catalyst.NBRO was prepared by co-precipitation method, in which the calcination of the precipitates obtained by adding excess NaOH solutions into the metal salt solution containing bismuth and ruthenium. The preparation with LiOH solutions replacing NaOH solutions was also carried out for comparison. The obtained oxides were characterized by XRD, RBS, EXAFS, AES, AAS, and SEM, and electrochemical measurements were performed using a three-electrode cell. The working electrode was the titanium disk covered with the oxides, which was mounted in a rotating-disk electrode equipment (Titanium disk method, TDM), and the electrolyte was 0.1 mol/L KOH solutions. Linear sweep voltammetry was performed for anodic and cathodic polarization, and oxygen reduction current was obtained with the difference in current measured in the solutions under N2 or O2 bubbling. Tafel plots of polarization curves gave Tafel slope and exchange current density, i 0. The air electrode, 23mm x 23mm x 0.2 mm, comprising the oxide catalyst, graphite, and PTFE was also prepared and tested with a half-open cell using 6 mol/L KOH solutions, in which the air electrode contacted the solution at one side and faced to air at the other side.The XRD pattern of NBRO was close to that of BRO prepared by solid mixing of Bi2O3 and RuO2 [4], while the EXAFS results indicated that sodium occupied near the A-site of pyrochlore structure as well as bismuth, and the elemental analysis revealed that sodium was about 4 to 6 at%. SEM observation also showed that the primary particle size of NBRO ranged from 20 nm to 40 nm and the secondary one was under 500 nm. Polarization curves by TDM gave that the overpotentials for OER and ORR were 200 mV and 300 mV, respectively, and Tafel slopes for both the reactions were about 40 mV/dec, which are much lower than the other materials such as platinum, cobalt, and other types of oxides. The air electrode using NBRO further demonstrated a high catalytic activity at two phase or three phase boundaries with 6 mol/L KOH solutions, which are, for example, a very high current density, 800 mA/cm2, for both OER and ORR, and a good cyclability up to 3000 cycles. Therefore, NBRO is expected to reduce the polarization of ARB and alkaline water electrolysis for EHP.

Influence of different Ni nanolayers thicknesses on single oscillator model parameters, optical band gap, and disordering energy in CNTs synthesized by Cu‐Ni @ a‐CH catalyst

In this paper, Cu‐Ni NPs @ a‐C:H thin films with different Ni layers thickness by co‐deposition of RF‐sputtering and RF‐plasma enhanced chemical vapor deposition (RF‐PECVD) were prepared using acetylene gas and Ni and Cu targets. The absorption edge and the optical dispersion parameters in CNTs synthesized by Cu‐Ni @ a‐C:H catalyst were studied. RBS measurements were performed, which confirmed the presence of Ni and Cu atoms in these films. Using Atomic Force Microscopy (AFM) system, the morphology of the films surface was investigated. The average diameter of the grown CNTs on Ni‐Cu NPs @ a‐C:H substrates were increased by increasing of Ni layers thickness. The values of dT/dλ and dR/dλ for grown CNTs without Ni show that the minimum value of the optical band gap corresponds to values of 2.55 and 2.56 eV, respectively. The absorption spectra peaks of films are about 400‐600 nm. These peaks are quite sharp for carriers band to band transitions and with increasing Ni layers thickness, there is a small shift. It can be seen that the dispersion energy Ed and the oscillator strength 𝑓 of CNTs synthesized by Cu‐Ni @ a‐C:H catalyst had the lowest values of 2.21 eV and 9.39 eV2, respectively, compared to the other films.

The relation between the average diameter of CNTs on Ni-Cu @ a-C:H catalyst with the optical absorption edge and the optical dispersion parameters.

In this study, the average diameter of the grown CNTs on Ni-Cu NPs @ a-C:H substrates were increased by increasing of Cu content. The obtained results indicated that by increase of Cu content, all films exhibited high-absorption spectra; therefore, we were facing an increase in the energy gap of films. The values of dT/dλ and dR/dλ measurements for grown CNTs with 75% Cu shown that maximum values of optical band gap correspond to with values of 2.48 eV and 2.90 eV, respectively. It can be seen that with increase of average diameter of the grown CNTs, the values of Urbach energy of films were increased. The RBS and EDAX measurements were confirmed presence of Ni and Cu atoms into films. The films deposited with 75% Cu were more smooth. Films deposited with 75% Cu have more disordered. Films deposited with 75% Cu atoms have maximum values of the oscillator strength f and the dispersion energy Ed about of 0.108 eV2 and 0.0543 eV, respectively.

Alpha-Spectroscopy to Determine 144Sm(α,γ) Activation Product

The purpose of this article is to describe the method used to determine the amount of 148Gd produced in the (α,γ) activation of enriched 144Sm samples. Advanced simulations are fitted to data to help constrain systematic uncertainties. The simulations are complimented with RBS measurements of the samples.

2230-PUB: A Portrait of HbA1c Levels amongst Adults Diagnosed with Diabetes Mellitus in Suburban Ahmedabad

Background: Many studies have estimated the prevalence of type 2 diabetes in suburban regions of India, such as Ahmedabad, Gujarat. However, there are few studies that examine the progression of HbA1C levels in patients diagnosed with diabetes over multiple visits to healthcare facilities. Objective: The primary aims of this study were to assess the efficacy of patient treatment at a diabetes care center in Gujarat, India and determine factors that may affect the progression of HbA1C levels over multiple visits. Methods: A total of 2,037 individuals aged ≥25 years (mean age 53.7 years) were included in this retrospective study. All individuals were previously diagnosed with diabetes and received treatment at the Dia Care Advanced Diabetes Care Center in Ahmedabad. Patient data was acquired from the clinic’s HealthPlix EMR. Results: Of those meeting inclusion criteria, males constituted 69.1%. The average BMI of all subjects was 29.7 kg/m2. Of all 2,037 subjects, only 22.0% (n=442) patients were tested for HbA1C levels multiple times. On average, these subjects underwent blood tests for HbA1C values 3.3 times in a one-year period and HbA1C levels dropped by 0.51 mg/dl (95% CI 0.70-0.31). There was a substantial correlation between the number of clinic visits and the decrease in HbA1C values (R = 0.71). Over the course of one year, 22.6% (19.9-25.1) of subjects who returned to the clinic saw a drop in HbA1C to levels not indicative of diabetes (≤6.5 mg/dl). A significant correlation was observed between RBS measurements and HbA1C levels. Notably, there was also a slight negative correlation between BMI and the number of clinic visits (R = 0.74). Conclusion: Results from this study reinforce the conventional wisdom that frequent visits to one’s physician help achieve glycemic control. More importantly, these results also reflect the success of suburban clinics such as Dia Care and call for physicians to stress the importance of clinic visits and address improvement in metabolic status regularly. Disclosure S. Shah: None. B.D. Saboo: None. S. Shah: None. D. Hasnani: None. V. Chavda: None. J. Kesavadev: Speaker’s Bureau; Self; Biocon, Novo Nordisk Inc., Sanofi-Aventis. H.B. Shah: None. K.J. Patel: None.

Heavy-ion RBS characterization of multilayer TiNx-SiO2-Si structures

Multilayer structures consisting of TiNx-SiO2-Si layers operating as MOS devices were constructed and tested for their electrical properties. RBS measurements were performed for the characterization of the structure of the devices. The results show a correlation between the structure found by RBS and the electrical performance of the devices.

Enhanced electrocatalytic activity of ion implanted rGO/PEDOT:PSS hybrid nanocomposites towards methanol electro-oxidation in direct methanol fuel cells

Reduced graphene oxide (rGO)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) nanocomposites have been synthesized via in situ polymerization technique. The synthesized nanocomposite films were implanted with Xe+ ions at different fluences of 3.3×1014, 3.3×1015 and 3.3×1016ionscm−2. The morphological, structural and elemental analyses of the implanted samples have been studied by FESEM, EDX, TEM, XRD, FTIR, Raman, RBS and XPS measurements. The electrochemical behavior of the irradiated electrodes has been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in presence of 0.5mM ZoBell's solution containing 0.5% KCl. The electrocatalytic activities of pristine and the irradiated electrodes towards methanol oxidation have been studied by cyclic voltammetry, chronoamperometry and cyclic stability. The electrocatalytic behavior reveals that the electrode irradiated with fluence 3.3×1016ionscm−2 exhibits different CV pattern than that of the other irradiated electrodes with slightly lower oxidation potential of 0.54V and higher anodic current density of 48mAcm−2 with enhanced cyclic stability of 93% at 800th cycles. The enhanced electrocatalytic activity can be attributed to the transformation of carbonaceous layer to the graphite like clusters and change in morphology of the nanocomposite at the fluence 3.3×1016ionscm−2 as observed from FESEM and TEM images.

IR-Photodetector Fabrication on Suspended Gesn Thin Layers

The energy bandgap (Eg) of Ge effectively shifts toward lower energies by alloying with Sn atoms. Strain-relaxed (SR) GeSn layers with more than 8% Sn content assumes a direct bandgap and can be potentially used for highly-sensitive photodetectors for the short-wavelength infrared (SWIR) region (Eg<0.6 eV). However, the epitaxial growth of SR GeSn alloys with high crystalline quality is challenging due to the large lattice mismatch with both Si and SR Ge [1]. One method for fabricating SR GeSn is based on the growth of compressively strained GeSn layers on SR Ge and releasing the strain by selective Ge under-etching [2]. In this study, a suspended IR-photodetector was fabricated using strain-relaxed Ge0.9Sn0.1 layer through microstructuring and Ge under-etching. The GeSn layers were grown on a Ge-buffered Si wafer [3] in a reduced pressure chemical vapor deposition tool using digermane and tin tetrachloride as Ge and Sn precursors. Two batches of detectors were fabricated; one based on GeSn on Ge and the other one based on suspended GeSn layers. Photolithography and ICP dry etching were used for patterning the detectors and the Ge underneath were removed by anisotropic selective etching using CF4 gas. XRD and RBS measurements indicate Sn contents of more than 10% without any Sn out diffusion. Raman spectroscopy shows the strain relaxation through Ge under-etching and layer release. The temperature dependence dependent photoluminescence spectra shown in Fig. 1 is in accordance with a direct band gap transitions of the GeSn layers around 0.5 eV. The effects of layer suspension on the absorption spectra and the photo response of the detectors will be discussed in the presentation. Fig. 1) Temperature dependence photoluminescence spectra of GeSn layer with 12% Sn content Acknowledgements: This work was supported by the Swedish Foundation for Strategic Research (SSF) and Vetenskapsrådet (VR).

(Invited) Naked Eye Blue Emission in Ce3+ Codoped SiOxNy: Toward Si-Based Light-Emitting Devices

Rare earth (RE) doped silicon host matrices has been broadly investigated to procure light emitting sources for integrated optoelectronics devices using the RE inter-4f transitions. Classically, those transitions are partially allowed and result in a very low absorption cross section inducing a non-efficient excitation. Due to its 5d-4f transitions, Ce3+ ion is quite different from other RE3+ ions due to a large absorption cross section (10-19 cm-2) as compared to the other RE3+ ions (10-21 cm-2).[1] Furthermore, due to its single valence d-orbital electron, the 5d band is strongly dependent on the local environment, resulting typically in a large Stokes shift depending on the host matrix composition.[2] Ce-doped SiOxNy films have been deposited by magnetron reactive sputtering from Si and CeO2 targets under nitrogen reactive gas atmosphere, with a typical thickness of 120 nm. Three investigation approaches were explored. In the first one samples grown with nitrogen highly rich plasma and a low Ce concentration (0.3 at.%) were tested. Photoluminescence (PL) experiments show a wide blue emission band ranging from 400 to 650 nm under UV photons excitation. Reference samples grown with lower nitrogen content did not show any visible emission. To explain the blue emission origin, we have studied extensively the role of different RE ions emitting centers in Ce-doped SiOxNy films (e.g. band tails, CeO2, Ce clusters, Ce3+ ions), with different activation scenarios. The results confirmed that blue emission is mainly due to the Ce3+ ion. In addition, based on refractive index measurements, the Ce-doped SiOxNy films compositions were deduced from a Bruggeman effective medium model, confirming the presence of Si3N4 and SiO2 phases. Furthermore, the presence of those phases was confirmed independently by their bonding signatures identified by infrared spectroscopy (FTIR) analysis. By means of photoluminescence excitation spectroscopy (PLE), a wide excitation range from 250 to 400 nm was evidenced and various excitation channels of Ce3+ ions involving direct or indirect mechanisms were proposed. In the second approach, we focused on samples grown at high nitrogen flow, where the effect of Ce3+ concentration variation was investigated. Under UV excitation, a strong blue emission is visible to the naked eyes for SiOxNy sample doped with high Ce3+ concentration (6 at. % as determined by RBS measurements). The external quantum efficiency was measured for the selected best emitting samples with help of integrating sphere. No saturation of the PL intensity was observed, demonstrating the absence of Ce clusters and/or silicate phase formation due do the nitrogen content.[3] We believe that this result is very promising for considering silicon based emitting applications. Finally, in the third approach we measured electroluminescence (EL) from Ce-doped SiOxNy prototype devices. Signal evolution was investigated as the function of the N flow, the Ce concentration and the inclusion of Al dopants with the aim to improve the electrical conductivity. The influence of these factors on observed EL was studied through the conduction mechanisms. [1] J.M. Ramírez, A. Ruiz-Caridad, J. Wojcik, A.M. Gutierrez, S. Estradé, F. Peiró, P. Sanchís, P. Mascher, B. Garrido, "Luminescence properties of Ce3+ and Tb3+ co-doped SiOxNy thin films: Prospects for color tunability in silicon-based hosts", J. Appl. Phys., 119 (2016) 113108. [2] J. Li, O.H.Y. Zalloum, T. Roschuk, C.L. Heng, J. Wojcik, P. Mascher, "Light Emission from Rare-Earth Doped Silicon Nanostructures", Advances in Optical Technologies, 2008 (2008) 10. [3] C. Labbé, Y.T. An, G. Zatryb, X. Portier, A. Podhorodecki, P. Marie, C. Frilay, J. Cardin, F. Gourbilleau, "Structural and emission properties of Tb3+-doped nitrogen-rich silicon oxynitride films", Nanotech., 28 (2017) 115710 (115714pp).

Preparation and characterisation of carbon-free Cu(111) films on sapphire for graphene synthesis

This work presents an investigation of carbon formed on polycrystalline Cu(111) thin films prepared by ion beam sputtering at room temperature on c-plane Al2O3 after thermal treatment in a temperature range between 300 and 1020°C. The crystallinity of the Cu films was studied by XRD and RBS/channeling and the surface was characterised by Raman spectroscopy, XPS and AFM for each annealing temperature. RBS measurements revealed the diffusion of the Cu into the Al2O3 substrate at high temperatures of > 700°C. Furthermore, a cleaning procedure using UV ozone treatment is presented to remove the carbon from the surface which yields essentially carbon-free Cu films that open the possibility to synthesize graphene of well-controlled thickness (layer number).

Thin film growth into the ion track structures in polyimide by atomic layer deposition

High-aspect ratio porous structures with controllable pore diameters and without a stiff substrate can be fabricated using the ion track technique. Atomic layer deposition is an ideal technique for depositing thin films and functional surfaces on complicated 3D structures due to the high conformality of the films.In this work, we studied Al2O3 and TiO2 films grown by ALD on pristine polyimide (Kapton HN) membranes as well as polyimide membranes etched in sodium hypochlorite (NaOCl) and boric acid (BO3) solution by means of RBS, PIXE, SEM-EDX and helium ion microcopy (HIM). The focus was on the first ALD growth cycles.The areal density of Al2O3 film in the 400 cycle sample was determined to be 51±3×1016at./cm2, corresponding to the thickness of 55±3nm. Furthermore, the growth per cycle was 1.4Å/cycle. The growth is highly linear from the first cycles.In the case of TiO2, the growth per cycle is clearly slower during the first 200 cycles but then it increases significantly. The growth rate based on RBS measurements is 0.24Å/cycle from 3 to 200cycles and then 0.6Å/cycle between 200 and 400cycles. The final areal density of TiO2 film after 400 cycles is 148±3×1015at./cm2 which corresponds to the thickness of 17.4±0.4nm. The modification of the polyimide surface by etching prior to the deposition did not have an effect on the Al2O3 and TiO2 growth.

Modelling the economically viable wood in the crown of European beech trees

Long-term forest development programs in Germany aim on an increase of close-to-nature broadleaf forest stands. This means that the economic importance of European beech is expected to increase. The economic potential of a tree basically consists of the stem as well as the economically viable wood volume in the crown. Due to the high morphological variability of European beech crowns, taper models are often not satisfactory for predicting the economically viable wood volume arising from crowns. Prediction models with a higher precision are recently still lacking. Aim of this study is thus the development of prediction model for the economically viable crown wood volume of European beech trees.We determined the distribution of the wood volume in the crown over the branch diameters using the multistage ‘randomized branch sampling’ method (RBS). The tree-specific wood volume distribution on the branch diameters were used to cluster all sampled trees into 3 groups. Additionally, we developed a method able to distinguish between economically viable and unviable crown branches. Basing on the RBS measurements as well as revenues and processing costs, we modeled the economically viable wood volume from the crown for each tree. To calculate the wood volume under bark, we parameterized a bark thickness function from disk samples of the trees.We showed that the European beech crowns could be clustered into 3 groups differing in their wood volume distribution. The economically viable wood volume in the crown significantly depended on this grouping parameter as well as diameter at breast height (DBH). By contrast, the total amount of wood in the crown only depended on DBH. The differing viable wood volumes in the crowns were thus explained by different wood distributions and not by differing total crown wood volume. To make the results applicable in practice forestry, the modelling results were used to develop a regression formula able to predict the economically viable wood volume in the crown depending on the DBH and the crown type. As the crown type can also be predicted via measurable tree covariates, the regression model of the viable wood volume in the crown can be used as a support tool for the management of European beech stands. Sensitivity analysis quantifies how harvest revenues and costs translate into different viable tree volume.