Papers by Keyword: Irradiation

Abstract: Silicon carbide (SiC) complementary metal-oxide-semiconductor (CMOS) technology and its circuit applications have been rapidly advancing, making the stability and reliability of planar p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) increasingly important. In this study, a channel-length-dependent threshold voltage instability was observed under both gate bias stress and gamma-ray irradiation. The results indicate that the majority of positive charge trapping originates from hole injection induced by external bias. Secondary ion mass spectrometry (SIMS) analysis confirmed the retention of aluminum species in the gate dielectric after thermal oxidation. Based on these experimental findings, a dopant diffusion model was proposed, suggesting that dopant contamination in the gate oxide is the primary cause of the channel-length-dependent instability.

Abstract: CuO/TiO₂ nanocomposites were synthesized using an economical drop-casting method and subsequently irradiated with high-energy C⁺ ions at fluence levels of 1 × 10¹⁴, 1 × 10¹⁵, 1 × 10¹⁶, and 1 × 10¹⁷ ions cm⁻². While ion irradiation of metal oxide materials is well established, the systematic investigation of C⁺ ion effects on the structural and optical properties of CuO/TiO₂ nanocomposites under these specific fluence conditions has been limited. This study therefore contributes new insight into how controlled C⁺ irradiation can tailor the behavior of this composite. These un-irradiated and irradiated nanocomposites were characterized using various techniques such as Energy Dispersive X-Ray Spectroscopy (EDX), Raman Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Photoluminescence (PL) Spectroscopy and Diffuse Reflectance Spectroscopy (DRS) to analyze structural, morphological and optical properties of these nanocomposites. The Raman and EDX analysis confirmed the formation of pure CuO/TiO₂ nanocomposites. The SEM results represent the spherical morphology of these nanocomposites in aggregated form. PL spectra’s depicted the pure and C⁺ ions irradiated nanocomposites were the same before and after C⁺ irradiation in the Photoluminescence emission. DRS results indicated that band gap energy was decreased as the fluence rate of C⁺ ions increased up to 1 × 10¹⁷ ions cm^-2.

Abstract: To understand the kinetics of changes in the majority current carriers Hall mobility temperature-dependency (in the temperature range of 77–300 K) in n- and p-type silicon crystals irradiated with high doses of high-energy particles during isochronous annealing, there are investigated P-doped n-Si samples irradiated with 25 MeV protons with dose of 8.1·10¹² cm^–2 at flux density of 1.5∙10¹¹ cm^–2·s^–1 and B-doped p-Si samples irradiated with 8 MeV electrons with dose of 1.0·10¹⁵ cm^–2 at flux density of 5.0·10¹² cm^–2·s^–1 at room temperature. Their isochronous annealing is performed in the temperature range of 80–500°C. The oscillatory character of the change in the majority current carriers Hall mobility in process of isochronous annealing of irradiated silicon samples is explained by the formation of disordered regions and the changes in degree of screening of their electric field potential barriers depending on charge states of nonequilibrium vacancies induced by irradiation.

Abstract: Am-241 is an alpha emitting isotope which can be used to fuel a nuclear battery via alphavoltaic effect by using a semiconductor to convert alpha radiation to electricity. The main issue of alphavoltaic battery is the radiation damage due to high energy alpha particle, resulted in a rapid decline in performance. Zinc oxide (ZnO) is known as a semiconductor with high radiation tolerance. In this study, the effect of annealing temperature to ZnO crystal was studied along with its alteration due to Am-241 irradiation overtime. The annealing temperatures were set at 450°C and 650°C. The irradiation process was carried out using Am-241 isotope for 12 days with an activity of 44.85 mCi and approximately 0.0866 MGy of absorbed dose. The crystal structure of fabricated and irradiated ZnO were investigated through X-ray Diffraction (XRD). The XRD diffraction pattern indicates that the crystal structure of ZnO is hexagonal wurtzite and still maintained after irradiation process. Raising the annealing temperature from 450°C to 650°C leads to a reduction in peak intensity. This change correlates with an increase in grain size post-irradiation. After exposure to alpha particle radiation, changes occurred in the diffraction peaks of ZnO. At 450°C annealing temperature, the intensity decreased by 94.822%, while at 650°C annealing temperature, the intensity decrease was 85.489%. This shows that increasing the annealing temperature can reduce the decrease in intensity after irradiation with alpha particles. The (002) plane shifted by 0.057˚ at 450°C annealing temperature and by 0.042˚ at 650°C after irradiation. In addition, the crystal lattice parameters increased after irradiation, which led to a change in the FWHM value and an increase in the crystal grain size.

Abstract: In recent studies, multifunctional oxide thin films have been given attention because of their special properties, such as ferroelectricity, gas sensitivity, and magnetism. Ion beam irradiation arose as a well-developed technique for tuning such properties. This study investigates the ion beam irradiation effects of He, Ni, and Kr ions on BiFeO₃, SnO₂, and ZnO thin films, respectively. The study utilized the 2013 version of Stopping and Range of Ions in Matter (SRIM) software to identify ion trajectory distribution and oxygen target vacancy differences on the Transport of Ions in Matter (TRIM) calculation types at various ion energies. A greater distribution of ion trajectories and higher peaks of oxygen target vacancies in oxide thin films were generated from monolayer TRIM than full cascade TRIM for all ion–thin-film pairs. The monolayer TRIM is preferable for ion beam irradiation of oxide thin films with its greater oxygen target vacancies and ion trajectory distribution for better analysis of ferroelectric coercive fields, adsorbed oxygen ions interaction with gas molecules, and the emergence of green emission for photoluminescence. The use of SRIM allows an alternative yet more flexible way of analyzing beam irradiation effects on oxide films considered in this work without resorting to costly or sophisticated experimental setups, which are a usual approach considered in most of the work under this topic. As such, the results presented here provide an initial or complementary basis should irradiation effect experiments require analysis of ion trajectories and oxygen vacancies.

Abstract: Achieving a strong bond between carbon fiber (CF) and recyclable thermoplastic polymer (TP) has always been highly sought after. So far, applying electron beam (EB) irradiation with optimal dose and cathode potential (V_c) has shown success in increasing mechanical properties of interlayered CFRTPs. However, with concern for durability and safety, higher strength is desired. Therefore, EB setting applying electron beam (EB) irradiation with cathode potential (V_c) to 170, 210, 225 or 250 kV was applied to CFRTPA (carbon fiber reinforced thermoplastic polyamide) articles just before shipping. Specimens were 9 CF plies alternating between 10 PA (polyamide) sheets, designated [TPA]₁₀[CF]₉. When optimal EB dose of 43.2 kGy is applied to both finished specimen surfaces after fabrication, experimental results show higher V_c setting of 250 kV can increase impact strength of the [TPA]₁₀[CF]₉ over that at 170 kV. In summary, the 250 kV-EB (250 kV) strengthens [TPA]₁₀[CF]₉ significantly, about 25 to 27% larger than that of 170 kV and zero (untreated). Based on Christenhusz and Reimer equation to calculate penetration depth, D_th of EBI into polymers, increasing V_c to 250 kV increased D_th to more than 2 times that at 170 kV.

Abstract: In order to analyze the influence of neutron irradiation on the critical event of cleavage fracture for the Chinese A508-3 (RPV) steel, the fracture morphology, microstructure and grain size of the irradiated specimens are observed and analyzed by optical microscope (OM) and scanning electron microscope (SEM). The results show that with the increase of neutron doses, the fracture mode of Chinese RPV steel material changes gradually from ductile fracture to ductile-brittle mixed fracture transformation. The brittle part for fracture mode of ductile-brittle fracture is cleavage fracture, and the non-metallic inclusions, microstructure and grain size grades are not significantly different from those of the specimens without cleavage fracture. In the same material, with increasing of neutron doses, the critical event size of the cleavage fracture will be reduced, and the percentage of the grain that satisfies the grain size of the cleavage critical event will increase correspondingly, resulting in an increase of the probability of cleavage fracture of the material. The fine grain with uniform distribution can improve partly the fracture toughness of the material and withstand higher neutron doses under the same conditions.

Abstract: Deforestation issues increased dramatically every year specially to produce paper. Therefore, to supplement the limited wood fibre resources, non-wood fibres especially sugarcane bagasse introduced an alternatives resolve for raw material is considered in paper-based industries. This study addresses the analysis of magnetic sugarcane bagasse materials as substitute fibres in papermaking. Paper is generally made with cellulose fibre which has some specific features used for educational, packaging, and cleaning purposes. Sugarcane bagasse (Saccarhum officinarum) is popular for its cellulose, holocellulose, and lignin that far more convenient than wood fibres. Meanwhile, the demands of magnetic material in magnetic papermaking industry has increased due to its excellent mechanical characteristics. As the magnetic paper shows some superiority in properties such as renewable use and folding resistance. The used of filler in this study is to alter the properties such as texture, opacity, brightness, dimensional stability, and overall printability. Thus, the used of ferrite (Fe) magnet as a filler can enhance the paper properties. Ferrite is recognized as a hard-magnetic material with distinct properties such as good mechanical hardness and chemical stability, therefore it is a much more convenient material for magnetic paper production. Through the observation under Scanning Electron Microscope (SEM), the image obtained shows that magnetics sugarcane bagasse paper was more convenient to be used as an alternative for paper making. Next, Fourier-Transform Infrared Spectroscopy (FTIR) recognizes the presence of a functional group of the magnetics sugarcane bagasse paper. Moreover, the chemical properties obtained from this study show that the magnetics sugarcane bagasse was as good as the commercial paper available in the industries. To increase the integrity of the paper, the radiation process by using gamma-ray was done to the paper to see the different for pre and post radiation.

Abstract: Tungsten (W) is suitable for solid targets of spallation neutron source due to its high neutron yield. The prediction of radiation effects of W is, therefore, of importance; especially, the influence of solute elements are complex and are not clearly known to date. We discuss here the solute effects using the first principles and kinetic Monte Carlo (KMC) calculations and show that Re and Os, which are nuclear transmutation products of W, can largely change the stability and mobility of radiation defects. Such influences of the solute elements seem to explain the unsolved mechanism of the microstructural evolution of W-based materials under irradiation.

Abstract: IASCC of stainless steel has been the most important issue for internals BFBs. The inspection data analysis indicates that there is a closed relation between irradiation fluence and cracked BFBs distribution. Then the nanoindentation and 3DAP tests were carried out to study the hardening and radiation induced segregation (RIS) behaviors of the reactor internals stainless steel specimens irradiated with 6 MeV Xe ions at room temperature. It is indicated that higher irradiation damage will cause more significant hardening and RIS and consequently increase the IASCC susceptibility.