Si Ion Irradiation Research Articles

Investigation on the machining mechanism of silicon modified by Au ion irradiation in elliptical vibration diamond cutting

Single-crystal silicon (Si) has important applications in semiconductor, infrared optics, and photovoltaic industries. However, Si is difficult to be machined precisely due to its hard and brittle characteristics. Ion irradiation is proposed as an advanced technology to reduce the hardness and brittleness for a covalent crystal, which is beneficial for the ductile machining process. In the present research, the simulation and experimental investigation of Si with Au ion irradiation were carried out firstly. As following, the grooving experiment is carried out by elliptical vibration cutting (EVC). the machining performance is compared with ordinary cutting (OC) and the material removal mechanism is elaborated. The critical depth of cut for brittle-to-ductile transition is nearly 7 times higher by EVC compared to OC. Initial verification of material modification was conducted by Raman spectra and cutting microgrooves. Finally, the ion irradiation damage mechanism and amorphous Si (a-Si)/crystalline Si (c-Si) machining deformation mechanism were analyzed in detail by transmission electron microscopy. The irradiated sample contains an amorphous layer of 1050 nm, a transition layer containing dislocations and nanocrystals, and a fully crystalline layer. During machining a-Si/c-Si interface, the machining defects in the amorphous layer will first absorb the energy and ensure that the crystalline layer does not produce subsurface damage. In summary, ion-irradiated Si can be achieved in the amorphous region at any depth position and the substrate ductile machining without subsurface damage generation by EVC.

5 MeV Si ion irradiation effects on structural and morphological properties of multiwalled carbon nanotubes

Carbon based nanomaterials (CBNs) such as multi walled carbon nanotubes (MWCNTs), graphene etc have attracted huge interest due to their widespread applications in contemporary nanotechnology. The ion bombardment is an important method which can be used for tuning of the structural and morphological properties of the CBNs. In the present work, we have carried out ion irradiation on MWCNTs (prepared by chemical vapour deposition method) with 5 MeV Si ions at different fluences ranging from 1 × 1014 to 5 × 1016 ions/cm2. The resulting structural and morphological modifications on the pristine MWCNTs have been characterized by using X-ray diffraction, Raman spectroscopy and field emission scanning electron microscopy. Results observed after successful characterization are compared with pristine sample results and we observed that the irradiation creates defects in MWCNTs and causes amorphized carbon nanomaterials depending on the fluence and energy deposited by energetic ions inside the MWCNTs.

Tailoring of structural and optical properties of GeOx thin films using 100 MeV Si ions

In the present work, the effects of 100 MeV Si ions on the structural and optical properties of GeOx thin films have been investigated. Thin films of Germanium oxide (GeOx) were deposited onto silicon substrates using electron beam evaporation technique. Subsequently, 100 MeV Si7+ ions were used to irradiate as-deposited films at different fluences ranging from 5 × 1012 to 2 × 1013 ions/cm2. As-deposited films are amorphous as evident from XRD and Raman results. After irradiation with a fluence of 5 × 1012 ions/cm2 the films show partial crystallization. The strong photoluminescence (PL) exhibited from as-deposited and irradiated films is in ultraviolet (UV) and blue region. The blue shift was observed in PL bands after ion beam irradiation. PL band intensity was found to vary with irradiation fluence. The possible mechanism of variation in the PL emission from GeOx thin films with Si ion irradiation has been studied.

Analysis of the variation in mechanical properties of α- and β-SiC under high-temperature Si-ion irradiation

The mechanical properties of silicon carbide (SiC) under high-temperature irradiation have been one of the focal issues for its application in nuclear systems, but the relevant mechanisms remain elusive. In this work, two SiC polytypes inducing α- and β-phase were irradiated by 1.35 MeV Si5+ with a fluence of 1.81 × 1016 ions/cm2 at 550 °C and 750 °C, respectively, to investigate the characteristics of irradiation-induced defects and structure and the variation of mechanical properties. Irradiation significantly affected the mechanical properties of both α- and β-SiC. The nanohardness and modulus of α-SiC increased with the increase of irradiation temperature, while for β-SiC they first increased and then decreased significantly. The results of GIXRD and Raman spectra indicated the irradiation-induced defects, lattice deformation, and the changes in the intensity of the Si-C bond region. It was found that the TEM characterization of irradiated SiC samples with numerous point defect clusters, extended defects and a legible defect band. Moreover, the nanohardness and modulus of both SiC types exhibited a critical temperature dependence and were affected by different dominant factors at high temperatures. The potential mechanisms governing the variation in mechanical properties at elevated temperatures of two irradiated SiC polytypes were explored.

Surface morphology and topography evolution of soda-lime silica glass after 1.0 MeV Si ion bombardment

Surface pattern formation on soda-lime silica glass by 1 MeV Si ion irradiation impinging at an angle of 70° with respect to the surface normal has been studied. Modification of surfaces were analyzed for total ion fluences applied between up to ions/cm2. The surface morphology and topography were studied by scanning electron microscopy (SEM), and atomic force microscopy (AFM). These surface techniques enabled the determination of roughness, characteristic wavelengths, and correlation lengths. In addition, electron dispersive spectroscopy (EDS) scans were applied on the surface topography to study the variation of the Si content on the obtained surface patterns. From the measurement of these variables, linear and non-linear regimes were established. At linear regime, the surface morphology develops from an initial flat surface giving rise to ripples for fluences up to ions/cm2. As the ion bombardment continues surface evolve into wrinkles finalizing at cellular-like structures, growing under an anomalous scaling process. The EDS scans indicate the presence of shadowing effects. The morphological changes observed can be explained in terms of a combination of thermal mass diffusion and geometrical factors during ion irradiation, including shadowing and subsequent (secondary) surface erosion effects adapted to few MeV energies.

Impact of Silicon Ion Irradiation on Aluminum Nitride‐Transduced Microelectromechanical Resonators

AbstractMicroelectromechanical systems (MEMS) resonators use is widespread, from electronic filters and oscillators to physical sensors such as accelerometers and gyroscopes. These devices' ubiquity, small size, and low power consumption make them ideal for use in systems such as CubeSats, micro aerial vehicles, autonomous underwater vehicles, and micro‐robots operating in radiation environments. Radiation's interaction with materials manifests as atomic displacement and ionization, resulting in mechanical and electronic property changes, photocurrents, and charge buildup. This study examines silicon (Si) ion irradiation's interaction with piezoelectrically transduced MEMS resonators. Furthermore, the effect of adding a dielectric silicon oxide (SiO2) thin film is unveiled. Aluminum nitride on silicon (AlN‐on‐Si) and AlN‐SiO2‐Si bulk acoustic wave (BAW) resonators are designed and fabricated. The devices are irradiated using 2 MeV Si+ ions at various fluxes up to a total fluence of 5 × 1014 cm−2. A time anneal is conducted to characterize device recovery. Scattering (S‐) parameters are measured in situ. Specific damage coefficients are derived to describe the radiation effect on resonant frequency (fr), quality factor (Q), motional resistance (Rm), and electromechanical coupling factor (). Furthermore, the damage coefficients for the bulk material properties of elastic modulus (E) and the piezoelectric coefficient (d31) are found.

Unraveling optical degradation mechanism of β-Ga2O3 by Si4+ irradiation: A combined experimental and first-principles study

Wide bandgap β-Ga2O3 is an ideal candidate material with broad application prospects for power electronic components in the future. Aiming at the application requirements of β-Ga2O3 in space photoelectric devices, this work studies the influence of 40 MeV Si ion irradiation on the microstructure and optical properties of β-Ga2O3 epi-wafers. Raman spectroscopy analysis confirms that Si ion irradiation destroys the symmetric stretching mode of tetrahedral–octahedral chains in β-Ga2O3 epi-wafers, and the obtained experimental evidence of irradiation leads to the enhanced defect density of VO and VGa–VO from x-ray photoelectron spectroscopy. Combined with first-principles calculations, we conclude that most configurations of VO and VGa–VO are likely non-radiative, leading to quenching of experimental photoluminescence intensity. Unraveling optical degradation mechanism and predicting the optical application of β-Ga2O3 devices in the space environment by combining ground irradiation experiments with first-principles calculations still be one of the focuses of research in the future.

Gradual modification of the YSZ structures by Au ion implantation and high-energy Si ion irradiation

Gold nanoparticles (Au-NPs) were created in crystalline yttria-stabilized zirconia (YSZ). (100)-, (110)- and (111)-oriented YSZ samples were implanted by 1 MeV Au+ ions at room temperature and fluences ranging from 1.5 × 1016 cm−2 to 7.5 × 1016 cm−2. The prepared Au: YSZ structures were annealed at 1100 °C for 1 h on air to support the Au-NPs coalescence and YSZ structure recovery. Subsequent irradiation with the 10 MeV Si3+ ions with a fluence of 5.0 × 1014 cm−2 was performed to enable gradual modification of Au-NPs. Au-depth profiles and YSZ structure modification in the produced samples were analysed via Rutherford backscattering spectrometry in channelling mode (RBS-C) and X-ray diffraction (XRD). RBS-C showed the gold distributed in the region of about 50–300 nm below the YSZ surface. The disorder was accumulated in the region with Au-NPs and the concentration of the disorder increases as a function of ion implantation fluence. The Zr-disorder was partially decreased after the annealing, while the subsequent Si-ion irradiation increased Zr-disorder again, however, the disorder does not reach values before the annealing. XRD measurement evidenced elastic deformation of the YSZ host lattice in the Au-implanted samples. Optical absorbance showed the appearance of the new absorption band at 550 nm for the Au-ion fluences above 5.0 × 1016 cm−2 ascribed to the Au-NPs formation. After the annealing, the absorption band is shifted to the wavelength of 580 nm which could be connected to the proceeding clustering of Au. The maximum absorption peak intensity increases which is connected to the increasing amount of the Au-NPs. Transmission electron microscopy (TEM) with Energy dispersive spectroscopy (EDS) confirmed the presence of Au-NPs in the implanted layer after the annealing. The subsequent Si-ion irradiation did not change the Au-NP shape which remained spherical with a slight size increase.

Nanoporous boron-doped diamond produced by a combination of high-energy ion irradiation and anodization

A wide electrochemical window makes boron-doped diamond (BDD) a promising electrode material. To utilize its excellent properties, nanopore formation on the surface to increase the specific surface area is highly desirable. Although anodization has the potential to produce nanoporous structures on the surface of materials, BDD has yet to be anodized due to its high physical and chemical stability. Here, we report that high-energy Si(II) ion irradiation forms sp2 defects, which enable the anodization of BDD, and demonstrate that this anodization results in the formation of nanoporous BDD.

Investigation of 500 keV Si ion induced surface structuring of Ni and Ti for enhancement of field emission properties

The present paper reports the investigation of surface morphology, elemental composition, phase changes and field emission properties of Si ion irradiated nickel (Ni) and titanium (Ti). The Ni and Ti targets have been irradiated with 500 keV Si ions generated by Pelletron accelerator at various fluences ranging from 6.9 × 1013 to 77.1 × 1013 ions/cm2. Stopping range of ions in matter analysis revealed higher values of electronic stopping and sputtering yield for Ni as compared with Ti. For both irradiated metals, electronic energy loss dominant over the nuclear stopping. The growth of induced surface structures have been analysed by using field emission scanning electron microscopy (FESEM) analysis. In case of Ni, as the ion fluence increases from 6.9 × 1013 to 65.8 × 1013 ions/cm2, the formation of spherical particulates, agglomers and sputtering is observed. Although in the case of Ti, with the increase of Si ion fluence from 11.6 × 1013 to 77.1 × 1013 ions/cm2, the formation of irregular‐shaped particulates along with crater and sputtered channels is observed. X‐ray diffraction (XRD) analysis shows that no new phase is identified. However, a significant increase in peak intensity is observed with increasing ion fluence. The variation in crystallite size and dislocation line density is also observed as a function of Si ion fluence. Fourier transform infrared spectroscopy analysis shows that no bands are formed after the Si ion irradiation. Field emission properties of ion‐structured Ni and Ti are well correlated with the growth of surface structures observed by SEM and dislocation line density evaluated by XRD analysis.

Radiation Effect in Ti-Cr Multilayer-Coated Silicon Carbide under Silicon Ion Irradiation up to 3 dpa

Replacement of conventional Zircaloy fuel cladding with silicon carbide (SiC) fuel cladding is expected to significantly decrease the amount of hydrogen generated from fuel claddings by the reaction with steam during severe accidents. One of their critical issues addressed regarding practical application has been hydrothermal corrosion. Thus, the corrosion resistant coating technology using a Ti-Cr multilayer was developed to suppress silica dissolution from SiC fuel cladding into reactor coolant under normal operation. The effect of radiation on adhesion of the coating to SiC substrate and its microstructure characteristics were investigated following Si ion irradiation at 573 K up to 3 dpa for SiC. Measurement of swelling in pure Ti, pure Cr and SiC revealed that the maximum inner stress attributed to the swelling difference was generated between the coating and SiC substrate by irradiation of 1 dpa. No delamination and cracking were observed in cross-sectional specimens of the coated SiC irradiated up to 3 dpa. According to analyses using transmission electron microscopy, large void formation and cascade mixing due to irradiation were not observed in the coating. The swelling in the coating at 573 K was presumed to be caused by another mechanism during radiation such as point defects rather than void formation.

Change of optical responses of Au nanoparticles induced by high-energy Si ion-irradiations

Change of optical responses of Au nanoparticles induced by high-energy Si ion-irradiations

Radiation hardness of Ge{2}Sb{2}Te{5} thin films to 80 MeV Si ion irradiation

We studied the effect of Si-ion irradiation on GeSbTe (GST) thin films. Amorphous GST thin films were irradiated with 80 MeV Si ions and studied using XRD, FESEM and UV–Vis-NIR measurements. After irradiation, we observed a slight increase in the particle size and a decrease in the optical bandgap. No phase transition from amorphous to crystalline was observed. Calculations using SRIM software provided insight into the possible reasons for the observed effects of swift heavy ions on GST. These minute changes in optical and micro-structural properties suggested that GST thin films were quite stable and radiation tolerant under the effect of 80 MeV Si ion irradiation.

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

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

Transmission electron microscopy study of extended defect evolution and amorphization in SiC under Si ion irradiation

ABSTRACTThe damage induced in 3C‐SiC epilayers on a silicon wafer by 2.3‐MeV Si ion irradiation for fluences of 1014, 1015, and 1016 cm−2, was studied by conventional and high‐resolution transmission electron microscopy (TEM/HRTEM). The evolution of extended defects and lattice disorder is followed in both the 3C‐SiC film and Si substrate as a function of ion fluence, with reference to previous FTIR spectroscopy data. The likelihood of athermal unfaulting of native stacking faults by point defect migration to the native stacking faults is discussed in relation to damage recovery. Threshold energy densities and irradiation doses for dislocation loop formation and amorphous phase transformation are deduced from the damage depth profile by nuclear collisions. The role of electronic excitations on the damage recovery at high fluence is also addressed for both SiC and Si.

Changes in properties of alpha-quartz and feldspars under 3 MeV Si-ion irradiation

Radiation-induced volume expansion (RIVE) in silicate minerals is recognized as the primary cause of long-term degradation in concrete structures. Although silicate minerals are the most abundant in rock-forming minerals of concrete aggregates, changes upon irradiation in these minerals are not clearly understood, particularly at high irradiation doses. In this study, tectosilicates, i.e., crystal quartz and two feldspars (albite and microcline), were irradiated with 3 MeV Si2+ to a maximum fluence of 2 × 1016 ions/cm2 (approximately two orders of magnitude higher than amorphization fluence), followed by a step height measurement and nano-indentation to quantify the change in volume and mechanical properties. The results show that the fluence dependence of RIVE is similar in quartz and feldspars, but the mechanism of the expansion differs. In quartz, amorphization is completed at a low fluence, followed by the relaxation of network and cavity formation. In feldspar minerals, amorphization occurs slowly. Subsequently, volume expansion is insignificant after the completion of amorphization. Hardness change appears to be a function of amorphization, whereas the Young's modulus is almost correlated with RIVE. The alkali ions in the silicate minerals can affect both the amorphization kinetics and the final amorphous structure.

Influence of 25 MeV Si ions and 25 MeV O ions on the chemical and structural properties of PEEK films

Poly (ether ether ketone) (PEEK) material can be used in a wide variety of fields, such as the aerospace, automotive, electronics, and nuclear industries. In this research, the irradiation effect of 25 MeV Si ions and 25 MeV O ions on the PEEK films was studied, focusing on the changes in chemical and structural properties. By analyzing surface morphology and microstructure evolution of the PEEK films after 25 MeV Si ion and 25 MeV O ion irradiation, particles were generated on surface of the PEEK after 25 MeV Si ion irradiation and black dots were generated on surface of the PEEK after 25 MeV O ion irradiation. The irradiation reduced the surface roughness of the PEEK films from the atomic force microscopy (AFM) results. The Fourier transform infrared (FTIR) results indicated that the groups and structure of the material were not changed by irradiation. The X-ray photoelectron spectroscopy (XPS) results showed that the contents of the chemical bonds C–C, C=O increased first and then decreased with the increasing of the fluences. The generated free radicals were observed by the electron paramagnetic resonance spectroscopy (EPR) at room temperature and the irradiation degradation mechanisms were analyzed. Thermal properties of the PEEK irradiated by 25 MeV O ions, indicating that a new secondary crystallization peak was found during the cooling stage. Consequently, the low fluences irradiation improves in the viscoelasticity and mechanical properties of PEEK films, while the high fluences irradiation reduces its performance.

Mechanical and microstructural response of the Al0.5CoCrFeNi high entropy alloy to Si and Ni ion irradiation

The nearly infinite compositional design space of high entropy alloys (HEAs) presents many opportunities to improve performance in extreme environments, particularly for nuclear reactors. The ability of some HEAs to resist high amounts of radiation damage, while well documented, has not yet been fully exploited. We studied the irradiation effect of different ions (Si and Ni) on the microstructure and mechanical properties of the Al0.5CoCrFeNi alloy at its equilibrium state, and of the individual response of each phase to irradiation. The results show a stronger effect of Si ions and differences in response of the ductile FCC (A1) and brittle ordered BCC (B2) phases towards irradiation. This finding highlights the need to further probe unexplored compositional spaces in HEAs, as further optimization is likely to yield further compositional and microstructural stability with practical applications.

Examination on High-Q NMR Transmit/Receiver Pickup Coils Made by YBa2Cu3O7-δ Thin Films

An important method to improve the sensitivity of a nuclear magnetic resonance (NMR) system is to increase the quality factor ( Q ) of the pickup coils. In this paper, we focus on the following three items: 1) effect of the surface resistance ( R s) of the YBa2Cu3O7-δ (YBCO) films on the Q of the NMR pickup coil; 2) relationship between coil line width and current flowing through coil; and 3) effect of Si-ion irradiation to YBCO films on the Q of the NMR pickup coils. In the study of 1), we examined the Q of the NMR pickup coils made by YBCO films with different R s and found that reduction of R s is useful in increasing the Q of the NMR pickup coils. In the study of 2), we simulated the current flowing in the NMR coils by an electromagnetic simulator, and found that wider microstrip lines of the NMR pickup coil increase the current. In the study of 3), we examined Si-ion irradiation effect to reduce R s of YBCO films, and found low irradiation energy and low irradiation density of Si-ion is useful to decrease R s and useful to obtain the high Q NMR pickup coils.

Irradiation behavior of Cf/SiC composite with titanium carbide (TiC)-based interphase

Interphase failures of traditional chemical vapor infiltration (CVI) synthesized SiC composites can often be found under irradiation conditions. Exploring new interphases and the corresponding synthesized method to improve the composites performance in irradiation environments are therefore important. In this study, molten-salt method was introduced to fabricate well-distributed TiC/Ti2AlC coating on carbon fiber (Cf) fabric, and the coated Cf fabric was subsequently used to synthesize SiC composites with layered carbides interphases via PIP process. SEM and TEM datum indicate that the interphases are well integrated with the carbon fibers and matrix. Irradiation behavior of the Cf/SiC composite was then studied by a series doses of Si ion irradiation at 300 °C. SPM shows that the irradiation induced swelling of interphases and matrix increase with the increasing irradiation doses, while the carbon fibers shrink along the axial direction after the irradiation and the shrinkage of the fibers increases with the irradiation doses. TEM investigation shows that no cracking and debonding of the interphase were detected even after the highest irradiation dose (∼20 dpa). The microstructure of the interphase remains the same as the pristine sample. Above results might prove that the interphases synthesized by molten-salt method has a good resistance to irradiation induced debonding. This pioneering work shows a new approach to fabricate the interphases and explore new fiber/matrix interphase designs for fission/fusion applications.