Energy Secondary Ion Mass Spectrometry Research Articles

Structure and RF performance evolution of polycrystalline silicon charge capture layer for advanced RF-SOI in in-situ annealing process

In this paper, the structures and radio-frequency (RF) properties of high resistivity silicon (HR-Si) wafers with a polycrystalline silicon (Poly-Si) charge capture layer after in-situ annealing were investigated. The thermal treatment significantly improves the wafer warpage and optimize the resistivity of Poly-Si/HR-Si interfaces. By using spreading resistance profiling (SRP), energy dispersive spectrometer (EDS) and secondary ion mass spectrometry (SIMS) technology, the rise of interfacial resistivity may be as results of the pyrolysis of the native oxide and the diffusion of hydrogen atoms. The transmission Kikuchi diffraction (TKD) analysis exhibited that the grains were recrystallized during the annealing, leading to the transformation from the small angle boundaries (SAGBs) into low-Σ coincidence lattice grain boundaries (CSL GBs). The drop of the bulk resistivity of the Poly-Si layer is attributed to the reduction of the total grain boundary (GB) density and the increase of the low electro-activity GB density. Moreover, the microwave losses and non-linearity of the RF-SOI with embedded Poly-Si layer was evaluated by on-chip testing based on CPW. It was determined that the decrease in the Poly-Si resistivity only worsens the microwave losses but not the non-linearity.

Selective thermal neutron transmutation doping with Gd masks in GaN semiconductors

For the first time, selective neutron transmutation doping was successfully performed on GaN through Gd masks, showing the feasibility of patternable doping through neutron irradiations. In collaborating with Oak Ridge National Laboratory, GaN with Gd masks was irradiated by directional neutrons. By using the Gd properties with high neutron absorption cross-sections, it was confirmed that the area covered by Gd masks on GaN was completely shielded from neutrons, and the uncovered area was doped with the generated Ge and 14C. Property differences were clearly identified in various ways when comparing the area exposed by neutrons and the area unexposed by neutrons. The discoloration by the ejected protons and elastic scattering of neutrons appeared only in the exposed area while the unexposed area remained the same as before irradiation. The aspect ratio of the patterned profile of GaN was estimated by comparing patterns on the front and backside. From energy dispersive X-ray spectroscopy spectra and secondary ion mass spectrometry measurement, the concentration difference between Ge and 14C as well as the exact concentration of produced 14C was also checked. Schottky barrier diodes on the selectively doped GaN were fabricated and investigated to study the electrical properties.

Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg

We have demonstrated a fabrication process for the Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg. An Ohmic contact with a contact resistance of 0.158 Ω cm2 is realized on p−-GaN ([Mg] = 1.3 × 1017 cm−3). The contact resistance of p-type GaN with higher Mg concentration ([Mg]=1.0 × 1019 cm−3) can also be reduced to 2.8 × 10−5 Ω cm2. A localized contact layer is realized without any etching or regrowth damage. The mechanism underlying this reduced contact resistance is studied by scanning transmission electron microscopy with energy dispersive x-ray spectroscopy and secondary ion mass spectrometry, representing a mutual diffusion of Ga and Mg atoms on the interface. Reductions in the barrier height and surface depletion width with the nitrogen-annealed Mg layer are confirmed by XPS and Hall effect measurements qualitatively.

Co-Sintering Study of Na0.67[Ni0.1Fe0.1Mn0.8]O2 and NaSICON Electrolyte–Paving the way to High Energy Density All-Solid-State Batteries

Sodium is a promising candidate for stationary storage applications, especially when the demand for lithium-ion batteries increases due to electromobility applications. Even though its energy density is lower, Na-ion technology is estimated to lead to a cost reduction of 30% compared to Li-ion technology. To improve safety as well as energy density, Na-based all-solid-state-batteries featuring solid electrolytes such as beta-alumina and sodium superionic conductors and cathode materials such as Na3V2(PO4)3 and NaxCoO2 have been developed over the past years. However, the biggest challenge are mixed cathodes with highly conductive interfaces, especially when co-sintering the materials. For example, a promising sodium superionic conductor type Na3Zr2Si2PO12 electrolyte sinters at 1,250°C, whereas the corresponding Na3V2PO12 cathode decomposes at temperatures higher than 900°C, posing a bottleneck. Thus in this paper, we synthesized Na0.62 [Ni0.10Fe0.10Mn0.80]O2 as cathode material for all-solid-state sodium-ion batteries via a relatively cheap and easy solution-assisted solid state reaction processing route. The thermal investigations of the pure cathode material found no degradation up to 1,260°C, making it a perfect match for Na3.4Zr2Si2.4P0.6O12 electrolyte. In our aim to produce a co-sintered mixed cathode, electron microscopy investigation showed a highly dense microstructure and the elemental mapping performed via energy dispersive X-ray spectroscopy and secondary ion mass spectrometry confirm that Na3.4Zr2Si2.4P0.6O12 and Na0.62 [Ni0.10Fe0.10Mn0.80]O2 do not react during sintering. However, the active cathode material forms a sodium rich and a sodium deficient phase which needs further investigation to understand the origin and its impact on the electrochemical performance.

A correlative method to quantitatively image trace concentrations of elements by combined SIMS-EDX analysis

The study demonstrates a new method to quantify Secondary Ion Mass Spectrometry (SIMS) images by using a synergetic combination of Energy Dispersive X-ray spectroscopy (EDX) and SIMS.

Improvement of extra low impact energy SIMS data reduction algorithm for process control

This work explores quantitative boron depth profiling in the top first nanometer using dynamic secondary ion mass spectrometry (SIMS). Dynamic SIMS measurements were performed with a magnetic sector CAMECA IMS Wf/SC Ultra, using extremely low impact energy O2+ (below 250 eV) sputtering. It was concluded that the modification of quantification protocol by the creation of a surface transient curve can provide a tool for the accurate characterization of low energy implantation wafers, including boron, under extremely low energy sputtering conditions with an oxygen beam.

Characterization of a Surface Hydrogen Charging Product Affecting the Mechanical Properties in 2205 Duplex Stainless Steel.

When 2205 duplex stainless steel (DSS) is immersed in simulated seawater under high hydrostatic pressure, or in an electrochemically hydrogen charged state, a spindle-shaped product is found in the ferrite phase that seriously deteriorates the mechanical properties of 2205 DSS. This paper systematically studied the composition, structure, and properties of the hydrogen charging product. The results of a slow strain rate tensile test show that the hydrogen charging product evidently reduces the elongation of 2205 DSS, and microcracks mainly initiate at the interface between the hydrogen charging product and the ferrite matrix at either a low or a high strain rate. However, the elongation recovers to that of the hydrogen free sample after heating the sample at 300 °C for 0.5 h. The nano-hardness and reduced modules of the product are higher than those of the ferrite and austenite phases. An element analysis by energy dispersive spectroscopy (EDS) and secondary ion mass spectrometry (SIMS) indicates that the Ni and H contents in the hydrogen charging product are higher than in the normal ferrite area, and X-ray diffraction shows the characteristic peak of iron hydride at 40.07°. Moreover, a differential scanning calorimeter (DSC) test demonstrated that the phase decomposition temperature of the product is 268 °C, which coincides with the fact that it dissolves at a high temperature caused by the focused electron beam during transmission electron microscopy (TEM) analysis. All experimental results indicate that the hydrogen charging product is a hydride of FeH or (Fe, Ni)H.

Measurement of SiGe composition in 3-D semiconductor Fin Field Effect Transistor devices

A Transmission Electron Microscopy (TEM)-based method is suggested to measure the composition of SiGe in 3-D structures using Electron Energy Loss Spectroscopy (EELS). The method accounts for the presence of films other than SiGe within the TEM lamella in the electron beam direction. The partial cross section of inelastic scattering of Ge was calibrated using a reference structure, which was earlier analyzed by Electron Energy Dispersive X-ray Analysis (EDX) and Secondary Ion Mass Spectrometry. The composition of SiGe in the p-FET Fin Field Effect Transistor devices with the overlaying Si oxynitride films was measured as a demonstration of the method. We show that the application of EELS yields smaller measurement errors of the SiGe composition as compared to EDX. The effect of beam damage in thin SiGe films surrounded by Si oxynitride is evaluated and compared to the blanket Si/SiGe structures. The method can be applied to the development of novel devices and state-of-the-art processes where the composition of SiGe plays a critical role.

Scalable Approach for Amorphous Thin Silicon Films Near‐IR Laser‐Induced Crystallization Using Nickel Absorption Layer

Technology for thin polycrystalline silicon films preparation is crucial for development of novel semiconductor devices, including flexible electronics. A method for thin polycrystalline silicon film preparation utilizing deposited nickel absorption layer which allows use of inexpensive 1064 nm pulsed YAG:Nd laser for laser annealing of magnetron‐sputtered amorphous silicon is reported here. Film morphology changes are visualized with scanning electron microscopy, its chemical composition and Ni fate upon laser irradiation are studied using X‐ray energy dispersion analysis and secondary ion mass spectrometry. Silicon crystalline structure changes and its homogeneity are characterized using Raman spectroscopy utilizing mapped spectral measurements. Range of laser radiation energy fluence (J cm−2) is established which allowed for preparation of fully polycrystalline silicon film with crystalline silicon Raman peak position and width comparable to that of single‐crystalline material. Nickel film is found to ablate substantially upon irradiation, leaving remains that can be easily removed by chemical etching.

Boron‐Containing Probes for Non‐optical High‐Resolution Imaging of Biological Samples

AbstractBoron has been employed in materials science as a marker for imaging specific structures by electron energy loss spectroscopy (EELS) or secondary ion mass spectrometry (SIMS). It has a strong potential in biological analyses as well; however, the specific coupling of a sufficient number of boron atoms to a biological structure has proven challenging. Herein, we synthesize tags containing closo‐1,2‐dicarbadodecaborane, coupled to soluble peptides, which were integrated in specific proteins by click chemistry in mammalian cells and were also coupled to nanobodies for use in immunocytochemistry experiments. The tags were fully functional in biological samples, as demonstrated by nanoSIMS imaging of cell cultures. The boron signal revealed the protein of interest, while other SIMS channels were used for imaging different positive ions, such as the cellular metal ions. This allows, for the first time, the simultaneous imaging of such ions with a protein of interest and will enable new biological applications in the SIMS field.

Boron-Containing Probes for Non-optical High-Resolution Imaging of Biological Samples.

Boron has been employed in materials science as a marker for imaging specific structures by electron energy loss spectroscopy (EELS) or secondary ion mass spectrometry (SIMS). It has a strong potential in biological analyses as well; however, the specific coupling of a sufficient number of boron atoms to a biological structure has proven challenging. Herein, we synthesize tags containing closo‐1,2‐dicarbadodecaborane, coupled to soluble peptides, which were integrated in specific proteins by click chemistry in mammalian cells and were also coupled to nanobodies for use in immunocytochemistry experiments. The tags were fully functional in biological samples, as demonstrated by nanoSIMS imaging of cell cultures. The boron signal revealed the protein of interest, while other SIMS channels were used for imaging different positive ions, such as the cellular metal ions. This allows, for the first time, the simultaneous imaging of such ions with a protein of interest and will enable new biological applications in the SIMS field.

Probing a chemical state during ultra low impact energy secondary ion mass spectrometry depth profiling

Ultra low impact energy SIMS allows probing a chemical state and provides qualitative information about strong covalent bonds.

Laser-Assisted Deposition of Transition Metal Coatings on Graphite

Abstract This paper reports the deposition of transition metal coatings on graphite by laser melting a pre-placed layer of powder particles using a continuous wave (CW) laser. Titanium, zirconium, and niobium coatings were successfully deposited on semiconductor grade graphite plates using the laser induced surface improvement (LISI) approach. The coatings produced were characterized using scanning electron microscope, energy dispersive spectrometry, X-ray diffraction, microhardness testing, and secondary ion mass spectrometry. Results show the formation of crack-free and dense transition metal coatings and the presence of carbide phases at the coating-graphite interface.

(Invited) Photo- and Cathodo-Luminescence of InAsxP(1-x)/InP Quantum Well Structures Under the Effects of Low-Energy Ion Bombardment

We investigate photo-luminescence (PL) and cathodo-luminescence (CL) spectra of InAsP/InP quantum well (QW) structures under exposure to low energy ions, and more generally to the particles generated in a plasma reactor typically used for etching such materials. The samples contain QWs of constant thickness (7 to 8 nm) and graded As/P concentration such that each QW produces, at low temperature, a PL line at a well-defined and resolved energy. Adjusting the depth of the QWs below the sample surface, the PL/CL of these QWs is thus the signature of the depth-dependent interaction with the ions and particles from the plasma. We have exposed our QW structures to different kinds of plasmas, containing variable mixtures of halogen-based molecules / hydrocarbons / nitrogen and Ar. Previous studies [1], in particular based on a similar approach of using the QW as an internal probe of the ion – material interaction, have shown that atomic ions with energies in the range of 100 to a few 100’s eV penetrate III-V materials (like GaAs or InP) through a channeling process [2], even if their direction of impingement is not favorable for channeling. The angular dispersion is in general sufficient to produce channeling. The ions channel a certain distance into the crystal, and then stop due to de-channeling mechanisms. As a consequence, a quenching of the PL for the QWs in the region where the de-channeling occurred takes place. We extended the analysis looking not only at the intensity of the PL lines, but also at their spectral characteristics upon exposure to the ion fluxes. Fig. 1 illustrates a selection of the effects that we were able to identify and explain [3]. On fig. 1-a, a sample was exposed to the particles flux from a plasma discharge in SiCl4/H2/Ar. Under the conditions of this plasma discharge, etching actually occurs at a rate ≈ 250-300 nm/min., and we had to be careful not to etch the whole QW structure immediately. Fig. 1-a shows that: - the signal for the two QWs at the lower wavelength seems to disappear. These QWs are the ones closest to the sample surface - the emission bands from the other QWs exhibit energy shifts Transmission electron microscopy and secondary ion mass spectrometry (SIMS) show that actually the two QWs closest to the top surface have not been etched. SIMS shows the penetration of Cl-species below the surface, which probably play a role in the quenching of the PL for these QWs The sample on fig. 1-a was undoped. On fig. 1-b, the same experiment is conducted for a sample with the same QW sequence as that of fig. 1-a, but n-type doped such that a large built-in electric field is created across the QWs region. One can see that this changes completely the shape of the PL lines. The reason for this change can be attributed to the quantum confined Stark effect (QCSE), as shown in [4]. Interestingly, as seen on fig. 1-b, the effect of the interaction with the etching ions is significantly more pronounced than for the undoped sample. We have shown that this is caused by a specific channeling interaction involving ions (probably Cl- ions) which strongly screen the QCSE. Using plasmas containing N2 (which effect is to reduce the etch rate), very significant blue shifts of the PL lines are seen (up to more than 7 nm). These were associated with the incorporation of N deep in the sample, occupying interstitial positions, thus creating local compressive lattice deformation that leads to the blue shifts [3]. All these effects will be discussed in the context of a model that we established to describe the modifications of the luminescence properties of the QW structures under the effect of low-energy ion bombardment. We will also describe experiments on samples where we take benefit of the plasma etching to define nanoscale structures and examine the spatial variation of the PL/CL spectra after interaction with the ion beams. [1] D. L. Green, E. L. Hu, P. M. Petroff, V. Liberman, M. Nooney, and R. Martin, J. Vac. Sci. Technol., B 11, 2249 (1993). [2] R. Germann, A. Forchel, M. Bresch, and H. P. Meier, J. Vac. Sci. Technol., B 7, 1475 (1989). [3] J.P. Landesman, J. Jiménez, C. Levallois, F. Pommereau, C. Frigeri, A. Torres, Y. Léger, A. Beck, and A. Rhallabi, J. Vac. Sci. Technol., A 34, 041304-1 (2016). [4] L. Viña, E. E. Mendez, W. I. Wang, L. L. Chang and L. Esaki, J. Phys. C: Solid State 20, 2803 (1987). Figure 1

Al2O3 coating as barrier against corrosion in Pb-17Li

Alumina coating, with a thickness of 1μm, has been manufactured by Pulsed Laser Deposition on EUROFER. A whole characterization of the interface, bare and coated, with stagnant Pb-17Li eutectic for 1000h at 550°C was performed using scanning electron microscopy, energy dispersive x-ray spectroscopy and secondary ion mass spectrometry. The results show that uncoated samples are damaged and suffer loss of material due to a solution process of the steel into the liquid metal, while corrosion process is insignificant for coated samples. Therefore, these results suggest a good performance of the alumina coatings under the test conditions.

An origin behind Rashba spin splitting within inverted doped sGe heterostructures

In this paper, we demonstrate why cubic Rashba spin splitting is observed within inverted doped strained germanium (sGe) hetrostructures. Magnetotransport measurements showed beating within the SdH oscillation, with fast Fourier analysis revealing cubic Rashba spin splitting to be present. A cubic Rashba coefficient of β=7.97×10−29 eVm3 and a spin-splitting energy of Δ=1.17 meV were determined. The source of the cubic Rashba spin splitting was identified from a combination of ultra low energy secondary ion mass spectrometry analysis and subsequent band structure modelling using Nextnano3. Ultra-low energy secondary ion mass spectrometry revealed an unintentional, highly B doped near surface region accounted for structure inversion asymmetry, whereas subsequent band structure modelling using Nextnano3 demonstrates how this asymmetric B doping generates structural inversion asymmetry within the sGe QW structure and cubic Rashba spin splitting realized.

Modified photoluminescence and photodetection characteristics of chemically grown SnO coated ZnO nanoneedles

The authors report on the synthesis of tin oxide (SnO) coated zinc oxide (ZnO) needlelike nanostructures and their modified light emission and detection features. The formation of SnO phase on ZnO surface has been revealed from energy dispersive x-ray analysis and secondary ion mass spectrometry studies. The luminescence response of the SnO-coated ZnO nanoneedles gets lowered compared to that of bare ZnO and is assigned to the lowering of radiative emission due to the occurrence of charge-carrier separation. Again in the heterostructured system, due to SnO led surface passivation, the band-edge emission becomes prominent and defect-related emission gets lowered. The photoconductivity response is found to be significantly enhanced for the SnO-ZnO heterostructured material formed with lower Sn:Zn molar ratio. The enhancement of photocurrent has been understood in the light of carrier separation and carrier multiplication processes occurring at the SnO-ZnO heterojunctions.

An O2+ probe energy study for boron quantification in Si1−xGex (0 ≤ x ≤ 1) using secondary ion mass spectrometry

With SiGe device technology still developing, a concomitant effort to develop accurate dopant quantification over the entire Si1−xGex (0≤x≤1) range using ultra low energy secondary ion mass spectrometry is required. Here we present a comprehensive secondary ion mass spectrometry study of the B11+ yield behaviour from a range of Si1−xGex (0≤x≤1) reference samples implanted with the same B dose. Depth profiling conditions include near normal incidence O2+ over an energy range of 0.2−1.0 keV. Quantification of the B concentration for each profile was achieved by determining the individual profile sensitivity factor. Only for EP≤300 eVwas the variation in sensitivity factor with Ge well described by a linear dependence over the whole Si1−xGex (0≤x≤1) matrix.

Corrosion of the alloys Magnox AL80, Magnox ZR55 and pure magnesium in air containing water vapour

Understanding the corrosion susceptibility of Magnox alloys during short- and long-term storage in moist air is important. Corrosion of Magnox AL80, Magnox ZR55 and magnesium has been studied in air containing water partial pressures between 200vppm and ∼80000vppm, at temperatures of 46°C–96°C. Specimens were exposed to air, with and without CO2, and argon gas. Metal consumption rates were measured and corrosion products characterised, using optical and scanning electron microscopy, energy dispersive x-ray microanalysis, x-ray diffraction and secondary ion mass spectrometry. Results show the importance of CO2 gas for suppressing breakaway corrosion in moist air.

High-temperature platinum resistance thermometry: the problem with silver and the case for gold

The diffusion of silver through quartz at high temperatures leads to contamination of the platinum sensing element of high temperature platinum resistance thermometers. While some protection of the PRT element may be afforded by the application of appropriate electric fields, the contamination of the quartz elements of silver fixed points causes their premature failure. Contamination is evidenced by the yellowish colour imparted to the glass by the silver particles growing within the quartz glass matrix. The presence of silver as the contaminating element has been confirmed unambiguously through energy dispersive x-ray analysis and secondary ion mass spectrometry. To mitigate the risk of silver contamination, the gold point is proposed as an alternative calibration point. PRT resistance ratios measured at the freezing points of silver and gold in different laboratories at different times are highly correlated. This suggests that the ITS-90 reference function might be extrapolated to 1064.18 °C (the gold fixed point). However, it remains unclear from the gold and silver PRT resistance ratios from the literature whether extrapolation of the reference function leads to the correct value at the gold point. A direct comparison of gold fixed points may be required to resolve the inconsistencies. Additional PRT data may help resolve the discrepancy.