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This manuscript outlines current research activities based on ion beam science at GNS Science in New Zealand. Ion beam analysis methods include Rutherford backscattering and nuclear reaction analys...

Zusammenfassung Hintergrund und Ziel Letzte-Hilfe-Kurse können Bürger befähigen, mehr Menschen ein Sterben zu Hause zu ermöglichen. Ziel der Studie ist die Evaluation der neu etablierten Letzte-Hilfe-Kurse für Kinder und Jugendliche. Materialien und Methoden Neun Letzte-Hilfe-Kurse für Kinder und Jugendliche mit insgesamt 128 Teilnehmern von 9–17 Jahren wurden durchgeführt. Die Evaluation basiert auf mixed-methods und erfolgte mittels eines Fragebogens. Ergebnisse 120 von 128 Teilnehmern (94 %) nahmen an der Evaluation teil. Die Teilnehmer schätzten die Möglichkeit, über Tod und Sterben zu reden. 94 % fanden den Kurs hilfreich für alle und 92 % wollen ihn weiterempfehlen. 89 % fanden die Kursinhalte leicht zu verstehen. Schlussfolgerungen und Ausblick Die Kurse für Kids/Teens werden von den Teilnehmern sehr gut angenommen. In Zukunft sollten die Kurse weiter verbreitet und in die Schulcurricula aufgenommen werden, um Informationen und Austausch zu Sterben und Begleitung am Lebensende zu ermöglichen.

New approaches to synthesize decorative black coatings on metallic surfaces are of significant research and commercial interest to manufacturing industries. In this work, decorative hard black coatings were deposited on a titanium surface by carbon ion implantation at ambient temperature. A 10 keV C+ beam was implanted on a Ti substrate to a fluence of 1–1.25 × 1018 C cm−2. Rutherford backscattering spectrometry and transmission electron microscopy results show that the implantation resulted in a bi-layered coating structure with a ~50 nm amorphous carbon layer at the surface followed by a ~50 nm amorphous titanium carbide intermixing layer deposited on top of a crystalline Ti surface. Raman spectroscopy confirms the formation of carbide intermixing layer and shows that the amorphous carbon layer has 15–20% sp3 content. Nanoindentation measurements show that the surface hardness of the implanted surface has increased by 72%, from 3.7 to 6.6 GPa, upon carbon implantation. Scratch tests further demonstrate a reduction in coefficient of friction in the implanted surface by 25%, signifying an improvement in wear-resistance of the coated materials. Colorimetry measurements reveal that carbon implantation reduces the luminosity of the Ti surface from 77 to 49 and chromaticity from 4.67 to 1.36, confirming incorporation of black color on Ti surface. The results demonstrate that C implantation onto a Ti surface at high fluence results in a black coating with high surface hardness and wear-resistance that can be employed in decorative surface applications for manufacturing industries.

Nanocrystal-based electronic devices with multiple functionalities offer one avenue toward novel passive and active electronic components. Here, we exhibit a planar and fully air-processed thin film device that demonstrates a photoinduced memristive behavior and can be used as a transistor, photodetector, or memory device. Following long-term (60 h) air exposure, unpackaged nanocrystal films develop reliable memristive characteristics in tandem with temperature, gate, and photoresponse. The on/off values of more than 50 are achieved, and the devices show long-term stability, producing repeatable metrics over days of measurement. The on/off behavior is shown to be dependent on the previous charge flow and carrier density, implying a memristive rather than switching behavior. These observations are described within a long-term trap-filling model. This work represents an advance in the integration of nanocrystal films into electronic devices, which may lead to the development of multifunctional electronic components.

Selective laser melting (SLM) is a laser-based powder bed fusion additive manufacturing technique extensively used in industry. One of the most commonly used alloys in SLM process is Ti-6Al-4V. However, its tribological properties when coated with N ion implantation is not well understood. In the ion implantation process used in this study, N2+ and N+ are accelerated to the energy of 60 keV and implanted to a fluence of 6 × 1017 at.cm−2. The effect of N ion implanted layer in terms of hardness values and how this implanted layer may affect wear process and wear rate is investigated in this paper. Sliding wear tests were conducted on SLM and conventionally processed samples implanted with N ions, followed by examining the wear tracks and coefficient of friction in order to explain the wear rate data obtained. The results showed that N+ implantation increased hardness within the depth of ~200 nm and reduced wear rate in SLM samples, while N2+ was not beneficial.

We report an intercluster compound based on co-deposition of the Au cluster [Au9(PPh3)8](NO3)3 and the fulleride KC60(THF). Electronic properties characteristic for a charge interaction between superatoms emerge within the solid state material [Au9(PPh3)8](NO3)3−x(C60)x, as confirmed by UV–VIS and Raman spectroscopy and I–V measurements. These emergent properties are related to the superatomic electronic states of the initial clusters. The material is characterized by Fourier-transform infrared spectroscopy, x-ray diffraction, Raman spectroscopy, and electrical measurements. Structural optimization and ab initio band structure calculations are performed with density functional theory to interpret the nature of the electronic states in the material; Bader charge calculations assign effective oxidation states in support of the superatomic model of cluster interactions.

The instability of pyrite nanocrystals’ (NCs) surfaces toward defect formation has until now impeded most applications of these materials. Here, we synthesize FeS2/FeSex core/shell NCs, with a shell largely composed of hexagonal-phase FeSe. The direct band gap of pyrite was not significantly changed due to the iron selenide coating while reduced trap state influence on charge carriers was revealed after the reaction forming the FeSex layer. The core/shell NCs had significantly higher surface electrical resistivity compared to pyrite. In addition, the iron selenide shell changed the net magnetic character of the NCs from diamagnetic to ferrimagnetic. The core/shell NC synthesis developed here eliminates the issue of intrinsic surface defects in pyrite NCs, and the NCs are expected to find utility as bifunctional NCs in room-temperature magnetoelectronic devices or in biomedical applications.

The long term stability of the AlN/Si interface is of paramount importance for reliability and energy efficiency of a wide range of microwave frequency devices. The propagation loss of high power amplifiers, the bandwidth of 5G telecommunication devices, the quantum efficiency of light emitting diodes and conversion efficiency of energy harvesters depend on this interface. We demonstrate that tensile biaxial strain is directly associated with an increase in electromechanical performance by comparing the piezoelectric modulus of different AlN films grown on Si (1 1 1) by three different methods. Only one sample showed a uniquely high d33 of 8.3 pmV−1. However, the d33 degrades almost linearly with storage time to a value of only 4.7 pmV−1 two years after sample preparation, due to the degradation of the interface by pressure-induced phase transformation of the crystalline Si substrate to amorphous Si. Hence, the time-dependent electromechanical performance of AlN is characteristic for the stability of the AlN/Si interface. We show that variations of measured d33 values in literature can directly be attributed to strain variations at the interface. Our AlN/Si interface comparison highlights that device performance for high frequency applications represents a compromise between energy efficiency and reliability.

The piezoelectric modulus of wurtzite aluminum nitride (AlN) is a critical material parameter for electrical components, ultimately contributing to the energy efficiency and achievable bandwidth of modern communication devices. Here, we demonstrate that the introduction of metallic point-defects (Ti, Zr, Hf) improves the piezoelectric modulus of as-received, unstrained, epitaxially grown AlN. The metals are incorporated by ion implantation with an acceleration energy of 30 keV to a fluence of 1015 at cm-2, which causes an elongation along the wurtzite c-axis. The stored internal strain energy increases the piezoelectric polarization of the thin AlN layer. This can equivalently be described by an enhancement of the piezoelectric modulus d33. The incorporation of 0.1 at. % Ti enhances the piezoelectric modulus by ∼30%; significantly exceeding gains obtained by alloying with the same amount of Sc. Published version The research was financed by the New Zealand Ministry for Business, Innovation, and Employment (No. C05X1712). This work used the JEOL JEM-ARM200F and FEI NanoLab G3 CX both funded by the Australian Research Council (ARC)—Linkage, Infrastructure, Equipment and Facilities (LIEF) Grant (Nos. LE120100104 and LE160100063, respectively) and located at the University of Wollongong Electron Microscopy Centre (UoW EMC), Australia.

Epitaxial AlN thin films were implanted with He at 8 keV along the c-axis growth direction with fluences ranging from 1015 to 1017 atoms/cm2. We find that the He implantation generated uniaxial tensile strain along the c-axis for all fluences that increased with fluence. There was an additional (002) X-ray diffraction peak for the highest He fluences of 5 × 1016 atoms/cm2 and 1017 atoms/cm2 that we interpret in terms of He bubble formation. He implantation leads to significant nitrogen (N) site disorder as evidenced by rapid broadening of the E2 (high) Raman mode with increasing fluence due to a reduction of the phonon mean free path. The piezoelectric coefficient, d33, reduces with increasing fluence, and is ~27% of the unimplanted d33 for the highest fluence. This result can be interpreted as implantation-induced nitrogen site disorder that randomises and reduces the Al–N dipoles. Thus, we show that while He implantation induces uniaxial strain, it decreases d33 due to implantation-induced N site disorder.

We report the evolution of uniaxial strain, resulting in an expansion of the c-axis in the wurtzite structure by up to 1 %, without significant degradation of the crystal structure of 30 keV Zr+ implanted epitaxial AlN films, grown on Si substrates. Raman and X-ray absorption spectroscopies demonstrated that the dominant defects are ZrAl, VAl and VN. The uniaxial strain can be attributed to a weakening of the Metal-N π bond along the c-axis. Monte Carlo simulations further predict the formation of a cation-rich region within the Zr implantation range, along with a buried anion-rich layer for all investigated fluences. The anion-rich layer undergoes a polarity inversion, which was experimentally confirmed by high-resolution high-angle annular dark field scanning transmission electron microscopy. Those microstructural changes influence the macroscopic electromechanical properties of AlN. The effective piezoelectric coefficient, d33, reduces from (7.0 ± 0.5) pm/V to (5.2 ± 0.5) pm/V at a fluence of 1015 at./cm2 Zr+. At higher fluences AlN undergoes a strain- and compositionally-induced polarity change, and the piezoelectric coefficient decreases due to crystalline damage. These results provide a pathway to optimise the performance of AlN by ion implantation for applications such as energy harvesting, light-emitting diodes and acoustic wave devices. In addition, the capability to engineer a buried polarisation inversion after AlN growth may enable novel device design.

We report the effects of implantation-induced-sputtering in determining the true magnetisation of iron nitrides formed by nitrogen implantation into iron films and the changes subsequently observed in their magnetic anisotropy. Iron thin films (40 nm) capped with gold layers were synthesized by ion beam sputtering. Nitrogen was implanted onto the thin film to a dose of 7 × 1016 cm-2. Dynamic ion-solid interaction simulations calculate the average nitrogen concentration within the iron thin films to be 13 at.%. Ion beam analysis was used to evaluate the composition and depth profile of the thin films before and after implantation. Cross-sectional transmission electron microscopy helped in identifying the implantation induced effects at the surface and interface of the thin film structure. Magnetisation measurements show that nitrogen implantation enhances the magnetisation of thin films and reduces their in-plane magnetic anisotropy. High resolution TEM and magnetisation results suggest formation of α’/α”-Fe16N2 with large magnetic moments and perpendicular magnetic anisotropy. The enhancement in magnetisation of the thin film with and without considering the sputtering losses is determined to be 15% and 5%, respectively. Our review of literature shows that underestimating the sputtering losses from implantation leads to reporting of inconsistent and reduced magnetic moments for Fe16N2.

Modern computing technology is based on silicon. To date, a cost-effective and easy to implement method to obtain isotopically pure silicon is highly desirable for attaining efficient heat dissipation in microelectronic devices and for hosting spin qubits in quantum computing. We propose that it is possible to use a 28Si+ ion beam to obtain an isotopically pure near-surface region in wafer silicon. However, this requires a highly stable, high current, and isotopically pure 28Si ion beam. This work presents and discusses the instrumentation details and experimental parameters involved in generating this required ion beam. Silane is used as the precursor gas and is decomposed in a Penning ion source to generate a 28Si+ ion beam. The influence of key ion source parameters such as the gas flow rate, magnetic field strength, and anode voltage is presented. An isotopically pure 28Si+ ion beam with 10 ± 0.5 μA current on the target is obtained at the GNS Science 40 kV ion implanter. The beam was observed to be stable for at least 8 h and contains less than 700 ppm of other Si isotopes. This high current and high purity provides opportunities to explore efficient modification of the isotopic distribution in a native Si substrate at ambient temperature. The results highlight opportunities offered by using Penning ion source based low energy ion implanters for the synthesis of isotopically modified Si surface regions-a technique also applicable to other materials such as diamonds and diamond-like carbon.

Display Omitted Growth and characterization of CNT based interconnects.Evaluation of the optimal BEOL-compatible metal-CNT interface.Nitrides provide a low contact resistance at the bottom metallization.A Ta-CNT interface has the lowest contact resistance for interconnect applications. Carbon nanotube (CNT) based interconnects with different metal-CNT contacts were prepared and characterized. All investigated contact materials are compatible with the back-end-of-line processing. For interconnect applications the length of the metal-CNT contact interface has to be extremely short, and has to have a low contact resistance. In order to provide a reliable interface between the metal and the CNTs the applied metal should form stable carbides. Indeed, Ta and Ti are beneficial in terms of contact resistance for the top metallization with Ta even outperforming Ti. However, those materials are non-noble metals and hence can oxidize. Besides the metals Ta and Ti, also their metal nitrides were investigated as bottom metallization. They outperform the pure metals since TaN and TiN are more resistant towards oxidation during subsequent processing steps. However, an extremely thin Ta layer also proves beneficial since in this case the formation of a conductive TaC during the CNT growth process is feasible. Unfortunately, insufficiently controlled oxidation processes occur which impairs the reproducibility and hence causes the average via to have a higher resistance.

We prepared CNT based vias on wafer scale. Based on the electrical characterization we extracted the localization length of the CNTs. While for short CNTs the classical transport regime is valid, the Anderson localization regime applies for longer CNTs. Supplementary the characteristic length scales were estimated based on the structure of the CNTs being in good agreement with the parameters extracted from the electrical measurements.

The following is the accepted manuscript of the original article: Marcel Melzer, Thomas Waechtler, Steve Müller, Holger Fiedler, Sascha Hermann, Raul D. Rodriguez, Alexander Villabona, Andrea Sendzik, Robert Mothes, Stefan E. Schulz, Dietrich R.T. Zahn, Michael Hietschold, Heinrich Lang and Thomas Gessner “Copper oxide atomic layer deposition on thermally pretreated multi-walled carbon nanotubes for interconnect applications”, Microelectron. Eng. 107, 223-228 (2013). Digital Object Identifier: 10.1016/j.mee.2012.10.026 Available via http://www.sciencedirect.com or http://dx.doi.org/10.1016/j.mee.2012.10.026 © 2013 Elsevier B.V. Carbon nanotubes (CNTs) are a highly promising material for future interconnects. It is expected that a decoration of the CNTs with Cu particles or also the filling of the interspaces between the CNTs with Cu can enhance the performance of CNT-based interconnects. The current work is therefore considered with thermal atomic layer deposition (ALD) of CuxO from the liquid Cu(I) β-diketonate precursor [(nBu3P)2Cu(acac)] and wet oxygen at 135°C. This paper focuses on different thermal in-situ pre-treatments of the CNTs with O2, H2O and wet O2 at temperatures up to 300°C prior to the ALD process. Analyses by transmission electron microscopy show that in most cases the CuxO forms particles on the multi-walled CNTs (MWCNTs). This behavior can be explained by the low affinity of Cu to form carbides. Nevertheless, also the formation of areas with rather layer-like growth was observed in case of an oxidation with wet O2 at 300°C. This growth mode indicates the partial destruction of the MWCNT surface. However, the damages introduced into the MWCNTs during the pre treatment are too low to be detected by Raman spectroscopy.

In this work we give an overview about recent developments in the integration technology of CNTs. We focus on wafer level approaches with the CVD and DEP method for growing as well as depositing CNTs in a defined way. So that we present methods to manipulate CNT growth structure, growth mode as well as growth inhibition in thermal CVD processes. This is highlighted by a unique growth structure opening new possibilities for CNT integration. Likewise, we show recent developments in scaling up the DEP method on wafer level. We round it up with the fabrication of CNT vias and MEMS structures containing CNT sensor elements.

For Cu/carbon nanotube(CNT) hybrid interconnect technology the growth of CNTs on a conductive substrate connected to Cu lines is required. CNTs were grown by catalytic chemical vapour deposition and the effect of a Cu layer beneath was investigated. By electron energy loss spectroscopy (EELS) we found the Cu to diffuse into the catalyst. This influences CNT growth. Therefore, incorporation of a sufficient diffusion barrier between the Cu layer and the substrate is required. As diffusion barriers we used Ta and TaN.

Before 1940, glass optics were generated by loose abrasive grinding. During World War II this started to be replaced by fixed abrasive grinding. Afterwards, in Europe, a typical supplier-driven market situation emerged. The booming post-war market for binoculars, camera lenses and eyeglasses provided the driving force behind the progress made in optical manufacturing. Therefore, from the mid-1950s onward, production sequences such as surface generation by fixed abrasive grinding, followed by labor intensive loose abrasive grinding and pitch polishing, had to be reorganized. These slow production cycles were replaced by multi-step, fixed abrasive grinding utilizing diamonds as abrasives, and by fast polishing methods.

From our glass polishing process of precision optics we know that its physical-chemical nature frequently leads to a complex interaction of several parameters determining the process and the resulting quality. Surface analysis using SIMS and WDX prove that surface and sharp edge polishing of integrated optics chips has to be watched critically in order to obtain useful parts in a reproducible manner.