Investigation of heavy ion irradiation effects on a charge trapping memory capacitor by C-V measurement

Heavy ion irradiation effects on charge trapping memory(CTM)capacitors with TiN/Al_(2)O_(3)/HfO_(2)/Al_(2)O_(3)/HfO_(2)/SiO_(2)/p-Si structure have been investigated.The ion-induced interface charges and oxide trap charges were calculated and analyzed by capacitance-voltage(C-V)characteristics.The C-V curves shift towards the negative direction after swift heavy ion irradiation,due to the net positive charges accumulating in the trapping layer.The memory window decreases with the increase of ion fluence at high voltage,which results from heavy ion-induced structural damage in the blocking layer.The mechanism of heavy ion irradiation effects on CTM capacitors is discussed in detail with energy band diagrams.The results may help to better understand the physical mechanism of heavy ion-induced degradation of CTM capacitors.

Comparison of total dose effects on SiGe heterojunction bipolar transistors induced by different swift heavy ion irradiation

The degradations in NPN silicon-germanium （SiGe） heterojunction bipolar transistors （HBTs） were fully studied in this work, by means of 25-MeV Si, 10-MeV C1, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current （IB）, current gain （β）, neutral base recombination （NBR）, and Early voltage （VA） were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in Ic was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail.

Impact of the displacement damage in channel and source/drain regions on the DC characteristics degradation in deep-submicron MOSFETs after heavy ion irradiation

This paper mainly reports the permanent impact of displacement damage induced by heavy-ion strikes on the deepsubmicron MOSFETs. Upon the heavy ion track through the device, it can lead to displacement damage, including the vacancies and the interstitials. As the featured size of device scales down, the damage can change the dopant distribution in the channel and source/drain regions through the generation of radiation-induced defects and thus have significant impacts on their electrical characteristics. The measured results show that the radiation-induced damage can cause DC characteristics degradations including the threshold voltage, subthreshold swing, saturation drain current, transconductanee, etc. The radiation-induced displacement damage may become the dominant issue while it was the secondary concern for the traditional devices after the heavy ion irradiation. The samples are also irradiated by Co- 60 gamma ray for comparison with the heavy ion irradiation results. Corresponding explanations and analysis are discussed.

Single event effect in a ferroelectric-gate field-effect transistor under heavy-ion irradiation

The single event effect in ferroelectric-gate field-effect transistor （FeFET） under heavy ion irradiation is investigated in this paper. The simulation results show that the transient responses are much lower in a FeFET than in a conventional metal-oxide-semiconductor field-effect transistor （MOSFET） when the ion strikes the channel. The main reason is that the polarization-induced charges （the polarization direction here is away from the silicon surface） bring a negative surface po- tential which will affect the distribution of carders and charge collection in different electrodes significantly. The simulation results are expected to explain that the FeFET has a relatively good immunity to single event effect.

Raman scattering investigation of C-doped a-SiO_2 after high energy heavy ion irradiations

Thermally grown amorphous SiO2 films were implanted at room temperature with 100 keV C-ions to 5.0× 10^17 or 1.2× 10^18 ions/cm2. These samples were irradiated at room temperature with 853 MeV Pb-ions to 5.0× 10^11, 1.0× 10^12, 5.0× 10^12 ions/cm2, or with 308 MeV Xe-ions to 1.0× 10^12, 1.0× 10^13, 1.0× 10^14 ions/cm2, respectively. Then the samples were investigated using micro-Raman spectroscopy. Prom the obtained Raman spectra, we deduced that Si-C bonds and sp2 carbon sites were created and nano-inclusions may also be produced in the heavy ion irradiated C-doped SiO2. Furthermore, some results show that Pb ion irradiations could produce larger size inclusions than Xe ions and the fluence. The possible modification process of C-doped discussed. inclusion size decreased with increasing the irradiation a-SiO2 under swift heavy ion irradiations was briefly

Irradiation effects of graphene and thin layer graphite induced by swift heavy ions

Graphene and thin graphite films deposited on SiO2/Si are irradiated by swift heavy ions(209Bi, 9.5 Me V/u) with the fluences in a range of 1011ions/cm2–1012ions/cm2 at room temperature. Both pristine and irradiated samples are investigated by Raman spectroscopy. For pristine graphite films, the 'blue shift' of 2D bond and the 'red shift' of G bond with the decrease of thickness are found in the Raman spectra. For both irradiated graphene and thin graphite films, the disorder-induced D peak and D' peak are detected at the fluence above a threshold Φth. The thinner the film, the lower the Φthis. In this work, the graphite films thicker than 60 nm reveal defect free via the absence of a D bond signal under the swift heavy ion irradiation till the fluence of 2.6 × 1012ions/cm2. For graphite films thinner than 6 nm, the area ratios between D peak and G peak increase sharply with reducing film thickness. It concludes that it is much easier to induce defects in thinner films than in thicker ones by swift heavy ions. The intensities of the D peak and D' peak increase with increasing ion fluence, which predicts the continuous impacting of swift heavy ions can lead to the increasing of defects in samples. Different defect types are detected in graphite films of different thickness values. The main defect types are discussed via the various intensity ratios between the D peak and D' peak(HD/HD).

Variation of Radiation Damage with Irradiation Temperature and Dose in CLAM Steel

The dependences of radiation induced defects on irradiation temperature up to 700℃ at 15 dpa and on irradiation dose up to 85 dpa at room temperature have been investigated by the heavy ion irradiation and the positron annihilation lifetime spectroscopy for the CLAM. A void size peak is observed at -500℃ where the vacancy cluster contains 9 vacancies and has an average diameter of 0.59 nm. The size of the vacancy clusters increases with the increase of irradiation dose at room temperature, and the vacancy cluster at 85 dpa consists of 9 vacancies and reaches a size of 0.60 nm in diameter. The absolute values of the void size at the peak and the increase of void size with dose in the CLAM steel are negligible compared to those of the normal stainless steels, indicating that the CLAM steel has good radiation resistant property.

Structural modification in swift heavy ion irradiated muscovite mica

Two-layer monoclinic （2M） muscovite mica sheets with a thickness of 12 μm are irradiated with Sn ions at room temperature with electronic energy loss （dE/dx）e of 14.7 keV/nm. The ion fiuence is varied between 1 ×10^11 and 1 ×10^13 ions/cm^2. Structural transition in irradiated mica is investigated by x-ray diffraction （XRD）. The main diffraction peaks shift to the high angles, and the inter-planar distance decreases due to swift heavy ion （SHI） irradiation. Dehydration takes place in mica during SHI irradiation and mica with one-layer monoclinic （1M） structure is thought to be generated in 2M mica after SHI irradiation. In addition, micro stress and damage cross section in irradiated mica are analyzed according to XRD data. High resolution transmission electron microscopy （HRTEM） is used on the irradiated mica to obtain the detailed information about the latent tracks and structural modifications directly. The latent track in mica presents an amorphous zone surrounded by strain contrast shell, which is associated with the residual stress in irradiated mica.

Ion-beam-assisted characterization of quinoline-insoluble particles in nuclear graphite

The irradiation behavior of graphite is essential for its applications in the nuclear industry.However,the behavioral differences of graphite remain obscure because of the very limited comprehension of its microstructural differences.One typical structure,the quinoline-insoluble(QI)particle,was investigated using IG-110 and NBG-18 graphite.After irradiation,the QI particles on the polished surface were proven to become hillocks,which were easily identifiable via scanning electron microscopy(SEM).Thus,a method that combined ion irradiation and SEM characterization was proposed to study the distribution and concentration of QI particles in graphite.During irradiation,the QI particles were found to evolve into densified spheres,which were weakly bonded with the surrounding graphite structures,thereby indicating that the densification of QI particles did not evidently contribute to graphite dimensional shrinkage.A much higher concentration of QI particles in NBG-18 than IG-110,which was suggested to be responsible for the smaller maximum dimensional shrinkage of former over the latter during irradiation,was characterized.

Structural integrity and damage of ZrB_(2) ceramics after 4 MeV Au ions irradiation

Ultra-high temperature ceramics have been considered as good candidates for plasma facing materials due to their combination of high melting point,high strength and hardness,high thermal conductivity as well as good chemical inertness.In this study,zirconium diboride has been chosen to investigate its irradiation damage behavior.Irradiated by 4 MeV Au^(2+)with a total fluence of 2.5×10^(16)cm^(-2),zirconium diboride ceramic shows substantial resilience to irradiation-induced damage with its structural integrity well maintained but mild damage at lattice level.Grazing incident X-ray diffraction evidences no change of the hexagonal structure in the irradiated region but its lattice parameter a increased and c decreased,giving a volume shrinkage of 0.46%.Density functional theory calculation shows that such lattice shrinkage corresponds to a non-stoichiometric compound as ZrB1.97.Electron energy-loss spectroscopy in a transmission electron microscope revealed an increase of valence electrons in zirconium,suggesting boron vacancies were indeed developed by the irradiation.Alo ng the irradiation depth,long dislocations were observed inside top layer with a depth of 750 nm where the implanted Au ions reached the peak concentration.Underneath the top layer,a high density of Frank dislocations is formed by the cascade collision down to a depth of 1150 nm.All the features show the potential of ZrB_(2) to be used as structural material in nuclear system.

Enhancement of hydroxyapatite dissolution through structure modification by Krypton ion irradiation

Hydroxyapatite(HA)synthesized by a wet chemical route was subjected to heavy ion irradiation,using4 Me V Krypton ion(Kr17+)with ion fluence ranging from 1×1013 to 1×1015 ions/cm2.Glancing incidence X-ray diffraction(GIXRD)results confirmed the phase purity of irradiated HA with a moderate contraction in lattice parameters,and further indicated the irradiation-induced structural disorder,evidenced by broadening of the diffraction peaks.High-resolution transmission electron microscopy(HRTEM)observations indicated that the applied Kr irradiation induced significant damage in the hydroxyapatite lattice.Specifically,cavities were observed with their diameter and density varying with the irradiation fluences,while a radiation-induced crystalline-to-amorphous transition with increasing ion dose was identified.Raman and X-ray photoelectron spectroscopy(XPS)analysis further indicated the presence of irradiationinduced defects.Ion release from pristine and irradiated materials following immersion in Tris(p H 7.4,37?)buffer showed that dissolution in vitro was enhanced by irradiation,reaching a peak at 0.1 dpa.We examined the effects of irradiation on the early stages of the mouse osteoblast-like cells(MC3 T3-E)response.A cell counting kit-8 assay(CCK-8 test)was carried out to investigate the cytotoxicity of samples,and viable cells can be observed on the irradiated materials.

Line-edge roughness induced single event transient variation in SOI Fin FETs

The impact of process induced variation on the response of SOI Fin FET to heavy ion irradiation is studied through 3-D TCAD simulation for the first time. When Fin FET biased at OFF state configuration（Vgs D0, Vds DVdd/ is struck by a heavy ion, the drain collects ionizing charges under the electric field and a current pulse（single event transient, SET） is consequently formed. The results reveal that with the presence of line-edge roughness（LER）, which is one of the major variation sources in nano-scale Fin FETs, the device-to-device variation in terms of SET is observed. In this study, three types of LER are considered： type A has symmetric fin edges, type B has irrelevant fin edges and type C has parallel fin edges. The results show that type A devices have the largest SET variation while type C devices have the smallest variation. Further, the impact of the two main LER parameters,correlation length and root mean square amplitude, on SET variation is discussed as well. The results indicate that variation may be a concern in radiation effects with the down scaling of feature size.