Trajectory bending and energy spreading of charged ions in time-of-flight telescopes used for ion beam analysis

Carbon foil time pick-up detectors are widely used in pairs in ion beam applications as time-of-flight detectors. These detectors are suitable for a wide energy range and for all ions but at the lowest energies the tandem effect limits the achievable time of flight and therefore the energy resolution. Tandem effect occurs when an ion passes the first carbon foil of the timing detector and its charge state is changed. As the carbon foil of the first timing detector has often a non-zero voltage the ion can accelerate or decelerate before and after the timing detector. The combination of different charge state properties before and after the carbon foil now induces spread to the measured times…

Mobility determination of lead isotopes in glass for retrospective radon measurements rad

In retrospective radon measurements, the 22-y half life of 210Pb is used as an advantage. 210Pb is often considered to be relatively immobile in glass after alpha recoil implanted by 222Rn progenies. The diffusion of 210Pb could, however, lead to uncertain wrong retrospective radon exposure estimations if 210Pb is mobile and can escape from glass, or lost as a result of cleaning-induced surface modification. This diffusion was studied by a radiotracer technique, where 209Pb was used as a tracer in a glass matrix for which the elemental composition is known. Using the ion guide isotope separator on-line technique, the 209Pb atoms were implanted into the glass with an energy of 39 keV. The di…

Atomic Layer Deposition of Ruthenium Films from (Ethylcyclopentadienyl)(pyrrolyl)ruthenium and Oxygen

Ru films were grown by atomic layer deposition in the temperature range of 275―350°C using (ethylcyclopentadienyl)(pyrrolyl)ruthenium and air or oxygen as precursors on HF-etched Si, SiO 2 , ZrO 2 , and TiN substrates. Conformal growth was examined on three-dimensional silicon substrates with 20:1 aspect ratio. ZrO 2 promoted the nucleation of Ru most efficiently compared to other substrates, but the films roughened quickly on ZrO 2 with increasing film thickness. The minimum number of cycles required to form continuous and conductive metal layers could be decreased by increasing the length of the oxygen pulse. In order to obtain well-conducting Ru films growth to thicknesses of at least 8―…

Influence of titanium-substrate roughness on Ca–P–O thin films grown by atomic layer deposition

Abstract Amorphous Ca–P–O films were deposited on titanium substrates using atomic layer deposition, while maintaining a uniform Ca/P pulsing ratio of 6/1 with varying number of atomic layer deposition cycles starting from 10 up to 208. Prior to film deposition the titanium substrates were mechanically abraded using SiC abrasive paper of 600, 1200, 2000 grit size and polished with 3 μm diamond paste to obtain surface roughness R rms values of 0.31 μm, 0.26 μm, 0.16 μm, and 0.10 μm, respectively. The composition and film thickness of as-deposited amorphous films were studied using Time-Of-Flight Elastic Recoil Detection Analysis. The results showed that uniform films could be deposited on ro…

Advanced time-stamped total data acquisition control front-end for MeV ion beam microscopy and proton beam writing

Many ion-matter interactions exhibit [email protected] time dependences such as, fluorophore emission quenching and ion beam induced charge (IBIC). Conventional event-mode MeV ion microbeam data acquisition systems discard the time information. Here we describe a fast time-stamping data acquisition front-end based on the concurrent processing capabilities of a Field Programmable Gate Array (FPGA). The system is intended for MeV ion microscopy and MeV ion beam lithography. The speed of the system (>240,000 events s^-^1 for four analogue to digital converters (ADC)) is limited by the ADC throughput and data handling speed of the host computer.

Ion-sputtering deposition of Ca–P–O films for microscopic imaging of osteoblast cells

Abstract An ion-beam sputtering technique was used to produce Ca–P–O films on borosilicate glass at room temperature from hydroxyapatite targets using nitrogen, argon and krypton beams at different acceleration voltages. The sputtering target was pressed from high purity hydroxyapatite powder or mixture of high purity hydroxyapatite powder and red phosphorus in order to optimise the film composition. The film composition, determined using time-of-flight elastic recoil detection analysis (TOF–ERDA), was found to be strongly dependent on the ion energy used for deposition. By extra doping of the target with P the correct Ca/P atomic ratio in the deposited films was reached. The films deposite…

In-Operando Lithium-Ion Transport Tracking in an All-Solid-State Battery.

An all-solid-state battery is a secondary battery that is charged and discharged by the transport of lithium ions between positive and negative electrodes. To fully realize the significant benefits of this battery technology, for example, higher energy densities, faster charging times, and safer operation, it is essential to understand how lithium ions are transported and distributed in the battery during operation. However, as the third lightest element, methods for quantitatively analyzing lithium during operation of an all-solid-state device are limited such that real-time tracking of lithium transport has not yet been demonstrated. Here, the authors report that the transport of lithium …

Atomic layer deposition of LixTiyOz thin films

Atomic layer deposition (ALD) was employed to deposit ternary films of LixTiyOz. The film growth at a deposition temperature of 225 °C was studied using both titanium tetra-isoropoxide (Ti(OiPr)4) and titanium tetrachloride (TiCl4) as titanium precursors. Lithium tert-butoxide (LiOtBu) was applied as the lithium source and water was used as the oxygen source for all metal precursors. The type of titanium precursor chosen strongly affected film growth: with TiCl4 the resulting LixTiyOz films were highly air-sensitive and the lithium concentration was low, whereas with Ti(OiPr)4 the films were relatively stable in air and with a lithium content which was easily controlled over a wide range. F…

Nanoscale etching of III-V semiconductors in acidic hydrogen peroxide solution: GaAs and InP, a striking contrast in surface chemistry

In this study of nanoscale etching for state-of-the-art device technology, the importance of surface chemistry, in particular the nature of the surface oxide, is demonstrated for two III-V materials. Striking differences in etching kinetics were found for GaAs and InP in sulphuric and hydrochloric acidic solutions containing hydrogen peroxide. Under similar conditions, etching of GaAs was much faster, while the dependence of the etch rate on pH, and on H2O2 and acid concentrations also differed markedly for the two semiconductors. Surface analysis techniques provided information on the product layer present after etching: strongly non-stoichiometric porous (hydr)oxides on GaAs and a thin st…

Characterization and Electrochemical Properties of Oxygenated Amorphous Carbon (a-C) Films

Amorphous carbon (a-C) films with varying oxygen content were deposited by closed-field unbalanced magnetron sputtering with the aim to understand the effect of oxygen on the structural and physical properties of the films and subsequently correlate these changes with electrochemical properties. The a-C films were characterized by transmission electron microscopy, helium-ion microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and time-of-flight elastic recoil detection analysis. The electrochemical properties were studied by electrochemical impedance spectroscopy and cyclic voltammetry with several redox systems (Ru(NH3)62+/3+, Fe(CN)64−/3−, dopamine an…

Alkylsilyl compounds as enablers of atomic layer deposition: analysis of (Et3Si)3As through the GaAs process

A new chemistry has been developed to deposit GaAs, the quintessential compound semiconductor. The ALD process is based on a dechlorosilylation reaction between GaCl3 and (Et3Si)3As. Characteristic ALD growth was demonstrated, indicating good applicability of the alkylsilyl arsenide precursor. ALD of GaAs produced uniform, amorphous and stoichiometric films with low impurity content. This was done with saturating growth rates and an easily controlled film thickness. Crystallization was achieved by annealing. Even though the growth rate strongly decreased with increasing deposition temperature, good quality film growth was demonstrated at 175 to 200 °C, indicating the presence of an ALD wind…

Wettability and compositional analysis of hydroxyapatite films modified by low and high energy ion irradiation

Abstract Hydroxyapatite-like thin films on silicon substrate were deposited using atomic layer deposition and were subjected to irradiation with Ar ions accelerated through 0.6–1.2 kV as well as 2 MeV 16 O + ions. After low energy Ar irradiation a significant reduction in contact angle was observed. However, the Ca/P atomic ratio remained unchanged. No reduction in contact angle was seen for high energy 16 O + irradiation. Atomic force microscopy showed the enhancement of floral-like pattern after low energy Ar bombardment while high energy oxygen irradiation lead to raised islands on as-deposited films.

Experimental evidence on photo-assisted O− ion production from Al2O3 cathode in cesium sputter negative ion source

The production of negative ions in cesium sputter ion sources is generally considered to be a pure surface process. It has been recently proposed that ion pair production could explain the higher-than-expected beam currents extracted from these ion sources, therefore opening the door for laser-assisted enhancement of the negative ion yield. We have tested this hypothesis by measuring the effect of various pulsed diode lasers on the O − beam current produced from Al 2O 3 cathode of a cesium sputter ion source. It is expected that the ion pair production of O − requires populating the 5d electronic states of neutral cesium, thus implying that the process should be provoked only with specific …

Photo-enhanced O−, H− and Br− ion production in caesium sputter negative ion source : no evidence for resonant ion pair production

It has been proposed that the negative ion yield of a caesium sputter ion source could be enhanced by promoting neutral caesium atoms to electronically excited 7p states supporting resonant ion pair production. We have tested this hypothesis by illuminating the cathode of a caesium sputter ion source with an adjustable wavelength laser and measuring its effect on the extracted beam currents of O−, H− and Br− anions. The laser exposure causes the beam currents to increase but the effect is independent of the wavelength in the range of 440-460 nm, which leads us to conclude that there is no evidence for resonant ion pair production. The photon-induced beam current enhancement scales with the …

Minimum detection limits and applications of proton and helium induced X-ray emission using transition-edge sensor array

Abstract We have determined minimum detection limits, MDLs, for elements 14 ⩽ Z ⩽ 86 using a transition-edge sensor array, TES array, and as a comparison using an Amptek X-123SDD silicon drift detector, SDD. This was done using a 3 MeV proton beam and a 5.1 MeV helium beam. MDLs were determined for a thin film sample on top of C substrate, and for a bulk sample containing mostly Al. Due to the higher peak-to-background ratio, lower detection limits were obtainable using the TES array for most of the elements. However, for elements 30 ⩽ Z ⩽ 45 the performance of the TES array was not as good as the SDD performance. This is due to the limitations of the TES used at energies >10 keV. The great…

Why are hydrogen ions best for MeV ion beam lithography?

The exposure characteristics of poly-(methyl methacrylate) (PMMA) for 2MeV ^1H^+, 3MeV ^4He^2^+ and 6MeV ^1^2C^3^+ have been investigated. The samples were characterised using Atomic Force Microscopy (AFM), optical microscopy and Raman spectroscopy. Development was carried out using a 7:3 propan-2-ol:H"2O mixture to determine clearing and cross-linking fluences. It was found that protons had a considerably wider tolerance to exposure variations and a smaller span of doses within the ion track. Furthermore, the void formation and consequent stress-induced surface roughening were smaller for protons. For all ions, the C?C bond Raman signal increased continuously with dose and fluence, even we…

Bandgap lowering in mixed alloys of Cs2Ag(SbxBi1−x)Br6 double perovskite thin films

Halide double perovskites have gained significant attention, owing to their composition of low-toxicity elements, stability in air and long charge-carrier lifetimes. However, most double perovskites, including Cs2AgBiBr6, have wide bandgaps, which limits photoconversion efficiencies. The bandgap can be reduced through alloying with Sb3+, but Sb-rich alloys are difficult to synthesize due to the high formation energy of Cs2AgSbBr6, which itself has a wide bandgap. We develop a solution-based route to synthesize phase-pure Cs2Ag(SbxBi1−x)Br6 thin films, with the mixing parameter x continuously varying over the entire composition range. We reveal that the mixed alloys (x between 0.5 and 0.9) d…

Energy-loss straggling of 2-10 MeV/u Kr ions in gases

Measurements have been performed on a time-of-flight setup at the Jyväskylä K130 cyclotron, aiming at energy-loss straggling of heavy ions in gases. Theoretical predictions based on recently developed theory as well as an empirical interpolation formula predict that straggling can be more than ten times higher than Bohr straggling in the MeV/u regime. Our measurements with up to 9.3 MeV/u Kr ions on He, N2, Ne and Kr targets confirm this feature. Our calculations show the relative contributions of linear straggling, bunching including packing, and charge exchange. Our results for stopping cross sections are compatible with values from the literature. Funding Agencies|EU||Academy of Finland …

Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas

The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 °C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF6 and O2 under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film’s removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film remova…

Ozone-Based Atomic Layer Deposition of Al2O3 from Dimethylaluminum Chloride and Its Impact on Silicon Surface Passivation

Dimethylaluminum chloride (DMACl) as an aluminum source has shown promising potential to replace more expensive and commonly used trimethylaluminum in the semiconductor industry for atomic layer deposited (ALD) thin films. Here, the Al2O3 DMACl-process is modified by replacing the common ALD oxidant, water, by ozone that offers several benefits including shorter purge time, layer-by-layer growth, and improved film adhesion. It is shown that the introduction of the ozone instead of water increases carbon and chlorine content in the Al2O3, while long ozone pulses increase the amount of interfacial hydrogen at silicon surface. These are found to be beneficial effects regarding the surface pass…

Production of pure samples of 131mXe and 135Xe

Pure samples of (131m)Xe, (133m)Xe, (133)Xe and (135)Xe facilitate the calibration and testing of noble gas sampler stations and related laboratory instrumentation. We have earlier reported a Penning trap-based production method for pure (133m)Xe and (133)Xe samples. Here we complete the work by reporting the successful production of pure (131m)Xe and (135)Xe samples using the same technique. In addition, we present data on xenon release from graphite.

Kansallinen kyselytutkimus englannin kielestä Suomessa : käyttö, merkitys ja asenteet

Development of a MeV ion beam lithography system in Jyväskylä

A lithographic facility for writing patterns with ion beams from cyclotron beams is under development for the Jyväskylä cyclotron. Instead of focusing and deflecting the beam with electrostatic and magnetic fields a different approach is used. Here a small rectangular beam spot is defined by the shadow of a computer-controlled variable aperture in close proximity to the sample. This allows parallel exposure of rectangular pattern elements of 5–500 μm side with protons up to 6 MeV and heavy ions (20Ne, 85Kr) up to few 100 MeV. Here we present a short overview of the system under construction and development of the aperture design, which is a critical aspect for all ion beam lithography syste…

Stability, sub-gap current, 1/f-noise, and elemental depth profiling of annealed Al:Mn-AlOX-Al normal metal-insulator-superconducting tunnel junctions

In this paper we report a study of the effect of vacuum annealing at 400◦C on the properties of normal metal-insulator-superconductor (NIS) tunnel junctions, with manganese doped aluminium (Al:Mn) as the normal metal, aluminum as the superconductor and amorphous aluminum oxide as the tunneling barrier (Al:Mn-AlOx-Al). The annealing treatment improves the stability of the junctions, increases their tunneling resistance and does not have a negative impact on the low-temperature current-voltage characteristics. The measured 1 / f resistance noise of the junctions also changes after annealing, in the best case decreasing by over an order of magnitude. All these observations show that annealing …

Bandgap lowering in mixed alloys of Cs2Ag(SbxBi1−x)Br6 double perovskite thin films

Halide double perovskites have gained significant attention, owing to their composition of low-toxicity elements, stability in air and long charge-carrier lifetimes. However, most double perovskites, including Cs2AgBiBr6, have wide bandgaps, which limit photo conversion efficiencies. The bandgap can be reduced through hallowing with Sb3+, but Sb-rich alloys are difficult to synthesise due to the high formation energy of Cs2AgSbBr6, which itself has a wide bandgap. We develop a solution-based route to synthesis phase-pure Cs2Ag(SbxBi1-x)Br6 thin films, with the mixing parameter x continuous varying over the entire composition range. We reveal that the mixed alloys (x between 0.5 and 0.9) dem…

Energy loss and straggling of MeV Si ions in gases

We present measurements of energy loss and straggling of Si ions in gases. An energy range from 0.5 to 12 MeV/u was covered using the 6 MV EN tandem accelerator at ETH Zurich, Switzerland, and the K130 cyclotron accelerator facility at the University of Jyväskylä, Finland. Our energy-loss data compare well with calculation based on the SRIM and PASS code. The new straggling measurements support a pronounced peak in He gas at around 4 MeV/u predicted by recent theoretical calculations. The straggling curve structure in the other gases (N2, Ne, Ar, Kr) is relatively flat in the covered energy range. Although there is a general agreement between the straggling data and the theoretical calculat…

Atomic layer deposition of Ru films from bis(2,5-dimethylpyrrolyl)ruthenium and oxygen

Abstract Ru thin films were grown on hydrogen terminated Si, SiO 2 , Al 2 O 3 , HfO 2 , and TiO 2 surfaces by atomic layer deposition from bis(2,5-dimethylpyrrolyl)ruthenium precursor and oxygen. The 4–20 nm thick films on these surfaces consisted of nanocrystalline hexagonal metallic ruthenium, regardless of the deposition temperature. At the lowest temperatures examined, 250–255 °C, the growth of the Ru films was favored on silicon, compared to the growth on Al 2 O 3 , TiO 2 and HfO 2 . At higher temperatures the nucleation and growth of Ru became enhanced in particular on HfO 2 , compared to the process on silicon. At 320–325 °C, no growth occurred on Si–H and SiO 2 -covered silicon. Res…

Effect of ozone concentration on silicon surface passivation by atomic layer deposited Al2O3

Abstract We study the impact of ozone-based Al2O3 Atomic Layer Deposition (ALD) on the surface passivation quality of crystalline silicon. We show that the passivation quality strongly depends on the ozone concentration: the higher ozone concentration results in lower interface defect density and thereby improved passivation. In contrast to previous studies, our results reveal that too high interface hydrogen content can be detrimental to the passivation. The interface hydrogen concentration can be optimized by the ozone-based process; however, the use of pure ozone increases the harmful carbon concentration in the film. Here we demonstrate that low carbon and optimal hydrogen concentration…

Stabilizing organic photocathodes by low-temperature atomic layer deposition of TiO2

Organic semiconductor light absorbers are receiving attention for their potential application in photoelectrochemical (PEC) cells for renewable fuels generation. Key to their advancement is precise control of the interfaces between charge-selective contacts, absorber layers, and electrocatalysts, while maintaining compatibility with an aqueous electrolyte environment. Here we demonstrate a new process for low-temperature atomic layer deposition (ALD) of TiO2 onto a P3HT:PCBM polymer blend surface for stable high-performance organic PEC photocathodes. This ALD TiO2 layer provides three key functions: (1) formation of an electron-selective contact to the polymer to enable photovoltage and pho…

Time-of-flight - Energy spectrometer for elemental depth profiling - Jyväskylä design

Abstract A new time-of-flight elastic recoil detection spectrometer has been built, and initially the main effort was focused in getting good timing resolution and high detection efficiency for light elements. With the ready system, a 154 ps timing resolution was recorded for scattered 4.8 MeV 4 He 2+ ions. The hydrogen detection efficiency was from 80% to 20% for energies from 100 keV to 1 MeV, respectively, and this was achieved by having an additional atomic layer deposited Al 2 O 3 coating on the first timing detector’s carbon foil. The data acquisition system utilizes an FPGA-card to time-stamp every time-of-flight and energy event with 25 ns resolution. The different origins of the ba…

Broadband Ultrahigh-Resolution Spectroscopy of Particle-Induced X Rays: Extending the Limits of Nondestructive Analysis

Nondestructive analysis (NDA) based on x-ray emission is widely used, for example, in the semiconductor and concrete industries. Here, we demonstrate significant quantitative and qualitative improvements in broadband x-ray NDA by combining particle-induced emission with detection based on superconducting microcalorimeter arrays. We show that the technique offers great promise in the elemental analysis of thin-film and bulk samples, especially in the difficult cases where tens of different elements with nearly overlapping emission lines have to be identified down to trace concentrations. We demonstrate the efficiency and resolving capabilities by spectroscopy of several complex multielement …

Transition-Edge Sensors for Particle Induced X-ray Emission Measurements

In this paper we present a new measurement setup, where a transitionedge sensor detector array is used to detect X-rays in particle induced X-ray emission measurements with a 2 MeV proton beam. Transition-edge sensors offer orders of magnitude improvement in energy resolution compared to conventional silicon or germanium detectors, making it possible to recognize spectral lines in materials analysis that have previously been impossible to resolve, and to get chemical information from the elements. Our sensors are cooled to the operation temperature (65 mK) with a cryogen-free adiabatic demagnetization refrigerator, which houses a specially designed X-ray snout that has a vacuum tight window…

Time-of-flight ERD with a 200mm2 Si3N4 window gas ionization chamber energy detector

Abstract Low energy heavy ion elastic recoil detection work has been carried out in Jyvaskyla since 2009 using home made timing detectors, a silicon energy detector and a timestamping data acquisition setup forming a time-of-flight–energy telescope. In order to improve the mass resolution of the setup a new energy detector was designed to replace the silicon solid state detector, which suffered from radiation damage and had poor resolution for heavy recoils. In this paper the construction and operation of an isobutane filled gas ionization chamber with a 14 × 14 mm 2 100 nm thick silicon nitride window are described. In addition to greatly improved energy resolution for heavy ions, the dete…

Potku – New analysis software for heavy ion elastic recoil detection analysis

Time-of-flight elastic recoil detection (ToF-ERD) analysis software has been developed. The software combines a Python-language graphical front-end with a C code computing back-end in a user-friendly way. The software uses a list of coincident time-of- flight–energy (ToF–E) events as an input. The ToF calibration can be determined with a simple graphical procedure. The graphical interface allows the user to select different elements and isotopes from a ToF–E histogram and to convert the selections to individual elemental energy and depth profiles. The resulting sample composition can be presented as relative or absolute concentrations by integrating the depth profiles over user-defined rang…

Nanoscale Etching of GaAs and InP in Acidic H<sub>2</sub>O<sub>2</sub> Solution: A Striking Contrast in Kinetics and Surface Chemistry

In this study of nanoscale etching for state-of-the-art device technology the importance of the nature of the surface oxide, is demonstrated for two III-V materials. Etching kinetics for GaAs and InP in acidic solutions of hydrogen peroxide are strikingly different. GaAs etches much faster, while the dependence of the etch rate on the H+ concentration differs markedly for the two semiconductors. Surface analysis techniques provided information on the surface composition after etching: strongly non-stoichiometric porous (hydr)oxides on GaAs and a thin stoichiometric oxide that forms a blocking layer on InP. Reaction schemes are provided that allow one to understand the results, in particular…

A new beamline for energy-dispersive high-resolution PIXE analysis using polycapillary optics

Abstract A new beamline for high energy resolution PIXE measurements is presented. This new setup includes options for both in-air and vacuum measurements. For the high energy resolution transition-edge sensor array, a polycapillary lens is used for detecting low-energy X-rays down to 0.5 keV and to increase the effective solid angle. X-ray transmission of the polycapillary lens was characterized using two calibration standards. The gain obtained by adding a polycapillary lens was 1.6–2.3 at energies between 2.1 keV and 4.5 keV. From 1.04 to 1.74 keV the gain is increased to 2.1–3.0, and at energies 4.9–8.0 keV the gain is between 1.6 and 0.65. The measured gain agreed well with theoretical…

Low-Temperature Atomic Layer Deposition of High-k SbOx for Thin Film Transistors

SbOx thin films are deposited by atomic layer deposition (ALD) using SbCl5 and Sb(NMe2)3 as antimony reactants and H2O and H2O2 as oxidizers at low temperatures. SbCl5 can react with both oxidizers, while no deposition is found to occur using Sb(NMe2)3 and H2O. For the first time, the reaction mechanism and dielectric properties of ALD-SbOx thin films are systematically studied, which exhibit a high breakdown field of ≈4 MV cm−1 and high areal capacitance ranging from 150 to 200 nF cm−2, corresponding to a dielectric constant ranging from 10 to 13. The ZnO semiconductor layer is integrated into a SbOx dielectric layer, and thin film transistors (TFTs) are successfully fabricated. A TFT with…

Mobility determination of lead isotopes in glass for retrospective radon measurements

In retrospective radon measurements, the 22-y half life of (210)Pb is used as an advantage. (210)Pb is often considered to be relatively immobile in glass after alpha recoil implanted by (222)Rn progenies. The diffusion of (210)Pb could, however, lead to uncertain wrong retrospective radon exposure estimations if (210)Pb is mobile and can escape from glass, or lost as a result of cleaning-induced surface modification. This diffusion was studied by a radiotracer technique, where (209)Pb was used as a tracer in a glass matrix for which the elemental composition is known. Using the ion guide isotope separator on-line technique, the (209)Pb atoms were implanted into the glass with an energy of …

Development of the Jyväskylä microbeam facility

Abstract A new microbeam facility is being constructed at the 1.7 MV Pelletron Accelerator in Jyvaskyla. The facility is designed for easy upgrading and incorporates a number of innovative features. Initially, it is based on a Heidelberg doublet with a design capability of a 3 × 5 μm beamspot at PIXE intensities and later upgraded to nanobeam performance. A thermal-expansion compensated rigid frame mounted on a mechanically isolated floor section is used to support the ion optical components. A compact-post focusing electrostatic deflector is used for high linearity beam scanning. This together with a novel time-stamped data collection (TDC) allows dynamic effects in IBIC, fluorescence blea…

Tang dynasty (618-907) bowl measured with PIXE

Brownish bowl originating from an underwater shipwreck located near Belitung island in the Java Sea, some 600 km south-east from Singapore, has been measured with particle induced X-ray emission. This study was a pilot project for the – now a spin-off company – Recenart research team where one target was to evaluate the authenticity of the different type of art objects. PIXE measurements were done from three different material positions from a single bowl received from a customer. These locations were categorized as a bluish/greenish pigment (under glaze), thick glaze and the body clay. When the obtained data was compared to the other references from different dynasties and kiln sites, the …

Direct Writing of Channels for Microfluidics in Silica by MeV Ion Beam Lithography

The lithographic exposure characteristic of amorphous silica (SiO2) was investigated for 6.8 MeV16O3+ions. A programmable proximity aperture lithography (PPAL) technique was used for the ion beam exposure. After exposure, the exposed pattern was developed by selective etching in 4% v/v HF. Here, we report on the development of SiO2in term of the etch depth dependence on the ion fluence. This showed an exponential approach towards a constant asymptotic etch depth with increasing ion fluence. An example of microfluidic channels produced by this technique is demonstrated.

Depth profiling of Al2O3+ TiO2 nanolaminates by means of a time-of-flight energy spectromete

Atomic layer deposition (ALD) is currently a widespread method to grow conformal thin films with a sub-nm thickness control. By using ALD for nanolaminate oxides, it is possible to fine tune the electrical, optical and mechanical properties of thin films. In this study the elemental depth profiles and surface roughnesses were determined for Al2O3 + TiO2 nanolaminates with nominal single-layer thicknesses of 1, 2, 5, 10 and 20 nm and total thickness between 40 nm and 60 nm. The depth profiles were measured by means of a time-of-flight elastic recoil detection analysis (ToF-ERDA) spectrometer recently installed at the University of Jyväskylä. In TOF-E measurements 63Cu, 35Cl, 12C and 4He ions…

Fabrication of microfluidic devices using MeV ion beam Programmable Proximity Aperture Lithography (PPAL)

Abstract MeV ion beam lithography is a direct writing technique capable of producing microfluidic patterns and lab-on-chip devices with straight walls in thick resist films. In this technique a small beam spot of MeV ions is scanned over the resist surface to generate a latent image of the pattern. The microstructures in resist polymer can be then revealed using a chemical developer that removes exposed resist, while leaving unexposed resist unaffected. In our system the size of the rectangular beam spot is programmably defined by two L-shaped tantalum blades with well-polished edges. This allows rapid exposure of entire rectangular pattern elements up to 500 × 500 μm in one step. By combin…

Development of an MeV ion beam lithography system in Jyväskylä

Abstract A lithographic facility for writing patterns with ion beams from cyclotron beams is under development for the Jyvaskyla cyclotron. Instead of focusing and deflecting the beam with electrostatic and magnetic fields a different approach is used. Here a small rectangular beam spot is defined by the shadow of a computer-controlled variable aperture in close proximity to the sample. This allows parallel exposure of rectangular pattern elements of 5–500 μm side with protons up to 6 MeV and heavy ions (20Ne, 85Kr) up to few 100 MeV. Here we present a short overview of the system under construction and development of the aperture design, which is a critical aspect for all ion beam lithogra…

Development of micro-contact printing of osteosarcoma cells using MeV ion beam lithography

Abstract For investigation of spatial effects in signalling between cells and also signal substances that trigger cell proliferation and behaviour we are developing a micro Contact Printing process ( μ CP ) . In order to allow printing of cells stamps with high aspect ratio are required and these have been fabricated using Programmed Proximity Aperture Lithography (PPAL) with 3 MeV 4 He 2 + ions to produce PMMA masters for casting the stamps in PDMS. A simple printing device was developed and the first results using this to print human osteosarcoma cells is demonstrated.

Resolution performance of programmable proximity aperture MeV ion beam lithography system

AbstractAn ion beam lithography system for light and heavy ions has been developed at the University of Jyväskylä's Accelerator Laboratory. The system employs a programmable proximity aperture to define the beam. The proximity aperture is made up of four Ta blades with precise straight edges that cut the beam in the horizontal and vertical directions. The blade positions and dimensions are controlled by a pair of high-precision linear-motion positioners. The sample is mounted on a X-Y-Z stage capable of moving with 100 nm precision steps under computer control. The resolution performance of the system is primarily governed by the proximity aperture. Pattern edge sharpness is set by the beam…

Porous inorganic–organic hybrid material by oxygen plasma treatment

In this paper, we present the pore formation on inorganic–organic hybrid material, ORMOCER©, by reactive ion etching. ORMOCERs are composed of inorganic backbone where organic side groups are attached by cross-linking. Etching of ORMOCER in oxygen plasma generates porous materials with different pore sizes depending on the etching parameters. In addition to planar films, this pore formation process is applicable to micro and nanostructures. Characteristics of porous materials are evaluated by contact angle measurement, scanning electron microscopy, Fourier transform infrared-attenuated total reflectance spectroscopy, time-of-flight elastic recoil detection analysis and Rutherford backscatte…

Strong absorption and ultrafast localisation in NaBiS2 nanocrystals with slow charge-carrier recombination.

Funder: AiF Project, no: ZIM-KK5085302DF0

Properties of AlN grown by plasma enhanced atomic layer deposition

Abstract The influence of growth parameters on the properties of AlN films fabricated by plasma-enhanced atomic layer deposition using trimethylaluminum and ammonia precursors was investigated. The atomic concentrations, refractive index, mass density, crystallinity and surface roughness were studied from the films grown in the temperature range of 100–300 °C with plasma discharge times between 2.5 and 30 s. The AlN films were shown to be hydrogen rich having H concentrations in the range of 13–27 at.% with inverse dependence on the growth temperature. The carbon and oxygen concentrations in the films were less than 2.6% and 0.2%, respectively. The refractive index and mass density of the f…

Heavy ion induced Ti X-ray satellite structure for Ti, TiN, and TiO2 thin films

Aluminum oxide/titanium dioxide nanolaminates grown by atomic layer deposition: Growth and mechanical properties

Atomic layer deposition (ALD) is based on self-limiting surface reactions. This and cyclic process enable the growth of conformal thin films with precise thickness control and sharp interfaces. A multilayered thin film, which is nanolaminate, can be grown using ALD with tuneable electrical and optical properties to be exploited, for example, in the microelectromechanical systems. In this work, the tunability of the residual stress, adhesion, and mechanical properties of the ALD nanolaminates composed of aluminum oxide (Al2O3) and titanium dioxide (TiO2) films on silicon were explored as a function of growth temperature (110-300 C), film thickness (20-300 nm), bilayer thickness (0.1-100 nm),…

Thermomechanical properties of aluminum oxide thin films made by atomic layer deposition

Funding Information: This work was carried out within the MECHALD project funded by Business Finland and is linked to the Finnish Centers of Excellence in Atomic Layer Deposition (Ref. No. 251220) and Nuclear and Accelerator Based Physics (Ref Nos. 213503 and 251353) of the Academy of Finland. Publisher Copyright: © 2022 Author(s). In microelectromechanical system devices, thin films experience thermal processing at temperatures some cases exceeding the growth or deposition temperature of the film. In the case of the thin film grown by atomic layer deposition (ALD) at relatively low temperatures, post-ALD thermal processing or high device operation temperature might cause performance issues…

Atomic Layer Deposition of Spinel Lithium Manganese Oxide by Film-Body-Controlled Lithium Incorporation for Thin-Film Lithium-Ion Batteries

Lithium manganese oxide spinels are promising candidate materials for thin-film lithium-ion batteries owing to their high voltage, high specific capacity for storage of electrochemical energy, and minimal structural changes during battery operation. Atomic layer deposition (ALD) offers many benefits for preparing all-solid-state thin-film batteries, including excellent conformity and thickness control of the films. Yet, the number of available lithium-containing electrode materials obtained by ALD is limited. In this article, we demonstrate the ALD of lithium manganese oxide, LixMn2O4, from Mn(thd)3, Li(thd), and ozone. Films were polycrystalline in their as-deposited state and contained le…

Ozone-Based Atomic Layer Deposition of Al2O3 from Dimethylaluminum Chloride and Its Impact on Silicon Surface Passivation

Dimethylaluminum chloride (DMACl) as an aluminum source has shown promising potential to replace more expensive and commonly used trimethylaluminum in the semiconductor industry for atomic layer deposited (ALD) thin films. Here, the Al2O3 DMACl-process is modified by replacing the common ALD oxidant, water, by ozone that offers several benefits including shorter purge time, layer-by-layer growth, and improved film adhesion. It is shown that the introduction of the ozone instead of water increases carbon and chlorine content in the Al2O3, while long ozone pulses increase the amount of interfacial hydrogen at silicon surface. These are found to be beneficial effects regarding the surface pass…

Programmable proximity aperture lithography with MeV ion beams

A novel MeV ion beam programmable proximity aperture lithography system has been constructed at the Accelerator Laboratory of the University of Jyvaskyla, Finland. This facility can be used to fabricate three dimensional microstructures in thick (<100μm) polymer resist such as polymethylmethacrylate. In this method, MeV ion beams from the 1.7 MV pelletron and K130 cyclotron accelerators are collimated to a beam spot of rectangular shape. This shape is defined by a computer-controlled aperture made of a pair of L-shaped Ta blades which are in close proximity to the sample to minimize the penumbra broadening. Here the authors report on development of the system, the controlling software, the …

Oxy-nitrides characterization with a new ERD-TOF system

Abstract A new time-of-flight (TOF) camera was installed on Elastic Recoil Detection (ERD) measurement setup on the Tandem Accelerator at Universite de Montreal. The camera consists of two timing detectors, developed and built by the Jyvaskyla group, that use a thin carbon foil and microchannel plates (MCP) to produce the start and stop signals. The position of the first detector is fixed at 18 cm from the target, while the position of the second detector can be varied between 50 and 90 cm from the first detector. This allows to increase time resolution by increasing the distance between the time-of-flight detectors or to increase solid angle by decreasing the distance. Moving the detector …

Coating and functionalization of high density ion track structures by atomic layer deposition

In this study flexible TiO 2 coated porous Kapton membranes are presented having electron multiplication properties. 800 nm crossing pores were fabricated into 50  m thick Kapton membranes using ion track technology and chemical etching. Consecutively, 50 nm TiO 2 films were deposited i nto the pores of the Kapton membranes by atomic layer deposition using Ti( i OPr) 4 and water as precursors at 250 °C. The TiO 2 films and coated membranes were studied by scanning electro n microscopy (SEM), X - ray diffraction (XRD) and X - ray reflectometry (XRR). Au metal electrod e fabrication onto both sides of the coated foils was achieved by electron beam evaporation. The electron multipliers were o…

Determination of electronic stopping powers of 0.05–1MeV/u 131Xe ions in C-, Ni- and Au-absorbers with calorimetric low temperature detectors

Abstract A new experimental system for precise determination of electronic stopping powers of heavy ions has been set up at the accelerator laboratory of the University of Jyvaskyla. The new setup, combining an established B-ToF system and an array of calorimetric low temperature detectors (CLTDs), has been used for the determination of electronic stopping powers of 0.05–1 MeV/u 131Xe ions in carbon, nickel and gold. Thereby advantage of the improved linearity and energy resolution of CLTDs as compared to the previously used ionization detector was taken to reduce energy calibration errors and to increase sensitivity for the energy loss determination, in particular at very low energies. The…

Aluminum oxide from trimethylaluminum and water by atomic layer deposition:The temperature dependence of residual stress, elastic modulus, hardness and adhesion

Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by na…

Thousands of words : a comparative study on the functions of pictorial illustrations in English language textbooks

Secondary electron flight times and tracks in the carbon foil time pick-up detector

Carbon foil time pick-up detectors used in the time-of-flight measurements of MeV energy ions have been studied in connection to time-of-flight-energy spectrometer used for heavy ion elastic recoil detection analysis. In experimental coincident TOF-E data characteristic halos are observed around light element isobars, and the origin of these halos were studied. The experimental data indicated that these halos originate from single electron events occurring before the electron multiplication in the microchannel plate. By means of electron trajectory simulations, this halo effect is explained to originate from single electron, emitted from the carbon foil, hitting the non-active area of the m…

Ultra-high resolution mass separator—Application to detection of nuclear weapons tests

Abstract A Penning trap-based purification process having a resolution of about 1 ppm is reported. In this context, we present for the first time a production method for the most complicated and crucially important nuclear weapons test signature, 133mXe. These pure xenon samples are required by the Comprehensive Nuclear-Test-Ban Treaty Organization to standardize and calibrate the worldwide network of xenon detectors.

Variation of lattice constant and cluster formation in GaAsBi

We investigate the structural properties of GaAsBi layers grown by molecular beam epitaxy on GaAs at substrate temperatures between 220–315 C. Irrespective of the growth temperature, the structures exhibited similar Bi compositions, and good overall crystal quality as deduced from X-Ray diffraction measurements. After thermal annealing at temperatures as low as 500 C, the GaAsBi layers grown at the lowest temperatures exhibited a significant reduction of the lattice constant. The lattice variation was significantly larger for Bi-containing samples than for Bi-free low-temperature GaAs samples grown as a reference. Rutherford backscattering spectrometry gave no evidence of Bi diffusing out o…

Oxidation-Induced Changes in the ALD-Al2O3/InAs(100) Interface and Control of the Changes for Device Processing

InAs crystals are emerging materials for various devices like radio frequency transistors and infrared sensors. Control of oxidation-induced changes is essential for decreasing amounts of the harmful InAs surface (or interface) defects because it is hard to avoid the energetically favored oxidation of InAs surface parts in device processing. We have characterized atomic-layer-deposition (ALD) grown Al2O3/InAs interfaces, preoxidized differently, with synchrotron hard X-ray photoelectron spectroscopy (HAXPES), low-energy electron diffraction, scanning tunneling microscopy, and time-of-flight elastic recoil detection analysis. The chemical environment and core-level shifts are clarified for w…

A simple timestamping data acquisition system for ToF-ERDA

A new data acquisition system, ToF-DAQ, has been developed for a ToF-ERDA telescope and other ToF-E and ToF-ToF measurement systems. ToF-DAQ combines an analogue electronics front-end to asynchronous time stamped data acquisition by means of a FPGA device. Coincidences are sought solely in software based on the timestamps. Timestamping offers more options for data analysis as coincidence events can be built also in offline analysis. The system utilises a National Instruments R-series FPGA device and a Windows PC as a host computer. Both the FPGA code and the host software were developed using the National Instruments LabVIEW graphical programming environment. Up to eight NIM ADCs can be han…

Depth profiling of Al2O3 + TiO2 nanolaminates by means of a time-of-flight energy spectrometer

Atomic layer deposition (ALD) is currently a widespread method to grow conformal thin films with a sub-nm thickness control. By using ALD for nanolaminate oxides, it is possible to fine tune the electrical, optical and mechanical properties of thin films. In this study the elemental depth profiles and surface roughnesses were determined for Al2O3 + TiO2 nanolaminates with nominal single-layer thicknesses of 1, 2, 5, 10 and 20 nm and total thickness between 40 nm and 60 nm. The depth profiles were measured by means of a time-of-flight elastic recoil detection analysis (ToF-ERDA) spectrometer recently installed at the University of Jyväskylä. In TOF-E measurements 63Cu, 35Cl, 12C and 4He ions…

Photo-assisted O− and Al− production with a cesium sputter ion source

It has been recently proposed that the production of negative ions with cesium sputter ion sources could be enhanced by laser-assisted resonant ion pair production. We have tested this hypothesis by measuring the effect of pulsed diode lasers at various wavelengths on the O− and Al− beam current produced from Al2O3 cathode of a cesium sputter ion source. The experimental results provide evidence for the existence of a wavelength-dependent photo-assisted enhancement of negative ion currents but cast doubt on its alleged resonant nature as the effect is observed for both O− and Al− ions at laser energies above a certain threshold. The beam current transients observed during the laser pulses s…

Lithography exposure characteristics of poly(methyl methacrylate) (PMMA) for carbon, helium and hydrogen ions

Abstract Poly(methyl methacrylate) is a common polymer used as a lithographic resist for all forms of particle (photon, ion and electron) beam writing. Faithful lithographic reproduction requires that the exposure dose, Θ, lies in the window Θ 0 ⩽ Θ Θ × 0 , where Θ 0 and Θ × 0 represent the clearing and cross-linking onset doses, respectively. In this work we have used the programmable proximity aperture ion beam lithography systems in Chiang Mai and Jyvaskyla to determine the exposure characteristics in terms of fluence for 2 MeV protons, 3 MeV 4 He 2 + and 6 MeV 12 C 3 + ions, respectively. After exposure the samples were developed in 7:3 by volume propan-2-ol:de-ionised water mixture. At…

Control of Oxygen Nonstoichiometry and Magnetic Property of MnCo2O4 Thin Films Grown by Atomic Layer Deposition

Spinel-structured (Mn,Co)3O4 thin films were reproducibly fabricated by atomic layer deposition (ALD) using Mn(thd)3, Co(thd)2, and ozone as precursors. A full control of the cation ratio was achieved in the temperature interval 140−160 °C within which also the growth rate remained constant. Precise control of the oxygen content of as-deposited MnCo2O4+δ films was achieved through postdeposition heat treatments at prefixed temperatures in air and N2 atmospheres, as evidenced from the monotonous increases of both the unit cell volume and the Curie temperature (TC) with increasing annealing temperature/decreasing oxygen partial pressure. The TC value varied from 92 K for the as-deposited MnCo…