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We present three different ways of transferring 3C-SiC layers grown on silicon on top of a SiC carrier using a carbon glue layer. Our main focus was upon the growth on the transition layer, as 3C-SiC does not feature any polarities in the or direction. We realized a stable and reproducible process by following a wet chemical approach, dealing with the difficulties of handling thin but freestanding 3C-SiC layers. By using this way, we transferred approximately 130 μm thick pieces using their horizontal hot-wall reactor (M10), which were chemo mechanically polished and afterwards fixed on our SiC carriers. Implementing such a seeding stack into our growth setup, we managed to grow between 20 μm and 130 μm thick layers on top. We have proven the possibility to grow on the transition layer. Furthermore, we observed a slight reduction in protrusion density, which is currently one of the main defects in such layers.

The effect of varying growth rate on the formation of defects in homo-epitaxially grown cubic silicon carbide (3C-SiC) is studied. Three growth rates are considered (30, 60 and 90 μm/hr) demonstrating that as the growth rate increases the density of point defects, as demonstrated by photo- luminescence, and stacking faults (SFs), as measured by a KOH etching procedure, increase. Scanning transmission electron microscopy images demonstrate generation, annihilation and closure of SFs as a function film thickness. High resolution X-ray diffraction is used to uncover the higher quality of homo-epitaxial with respect hetero-epitaxial films through the examination of the sample mosaicity and SF density.

Stacking Faults (SFs) are the main defect of 3C-SiC material and in this work a detailed study of this typology of defect is presented. We studied the behavior of SFs with High Resolution XRD and STEM analysis. The homo-epitaxial growth was proposed as a solution for the reduction of SFs density in 3C-SiC material and the influence of the growth condition on the SFs density was studied. The knowledge of the mechanism of SFs reduction is crucial for the development of a high quality material for devices fabrication.

We report on the growth of bulk 3C-SiC by sublimation on epitaxial seeding layers (3C-SiC/Si) from chemical vapor deposition. We have reached a materials thickness of 0.85 mm and an area of 10.5 cm2 which can be enlarged further. The high crystalline quality is characterized by the absence of secondary polytype inclusions and the absence double position grain boundaries.

A new technique with micro-Raman and micro-PL analysis is proposed to detect defects in 3C-SiC epitaxial films. The high-power of an above band-gap laser is used to increase locally the free carriers density in un-doped epitaxial material (n < 1016 cm-3). The electronic plasma couples with the longitudinal optical (LO) Raman mode determining the so-called LOPC effect. The Raman shift of the LO phonon-plasmon-coupled mode (LOPC) changes as the free carriers density is modified. Crystallographic defects induce a modification of the free carriers density determining a change in the Raman shift of LO mode and in the PL emission from the 3C-SiC gap. Thus we suppose that the results observed are connected to crystallographic defects and we propose this technique as a methodology to analyze extended defects in 3C-SiC material because a detailed study of defects in 3C-SiC has not yet been performed.

3C-SiC layers (7 and 15 μm thick), epitaxially grown on silicon, were covered with gold nanoparticles by immersion in a solution containing HF and KAuCl4. The surface of the layers played a crucial role in the morphology of the deposited metal network and large gold agglomerates developed on the pronounced antiphase domain boundaries of the thinner layer. Preferential growth was not observed on the smooth surface of the 15 μm thick layer. Rutherford backscattering spectrometry and electron microscopy outlined a progressive nucleation that takes place for less than 60 s immersion times under a kinetic control process. For longer deposition time each cluster grows under a diffusion control process, resulting in flower-like gold particles. However, the nucleation and growth processes can be strongly modified by multiple immersions in solution after rinsing in water. The adopted procedure allows the tailoring of the particles size and avoids the aggregation, therefore improving by about 1 order of magnitude t...

International audience; The article describes the main achievements of the NUMEN project together with an updated and detailed overview of the related R&D activities and theoretical developments. NUMEN proposes an innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the fact that the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave functions in the two types of processes and the formal similarity of the transition operators. First experimental results obtained at the INFN-LNS laboratory for the$^{40}$Ca($^{18}$O,$^{18}$Ne)$^{40}$Ar reaction at 270MeV give an encouraging indication on the capability of the proposed technique to access relevant quantitative information. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer. The former is used for the acceleration of the required high resolution and low emittance heavy-ion beams and the latter is the large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the experimental resolution and sensitivity required for the accurate measurement of the DCE cross sections at forward angles. However, the tiny values of such cross sections and the resolution requirements demand beam intensities much larger than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities in this perspective is part of the NUMEN project and will be discussed in the article.

In this paper the defects generated by ion implantation in 4H-SiC DIMOSFET (Double Implanted MOSFETs), and their evolution after annealing process, have been studied in detail. The point defects generated by the source or body implantation process have been detected by micro-photoluminescence (µPL) and the effect of these defects on the electrical characteristics of the DIMOSFET has been studied. The role of the annealing process has been carefully investigated by using different temperatures. It appears fundamental for the restoring of the crystal damage. The effect of the ion implantation dose has been investigated as well. By reducing the source ion implanted dose a large decrease of point defects has been detected and a considerable improvement of the electrical characteristic of the DIMOSFET has been observed.

3C-SiC devices are hampered by a high crystal defect density due to the hetero-epitaxial growth of these films, which results in the presence of stacking faults (SF). In this paper high growth rate CVD processes have been used to try to reduce the SF density in 3C-SiC films. In a first step a high growth rate (30 µm/h) has been used to grow 50 µm thick 3C-SiC layer on (100) Si. Then the silicon substrate was removed via etching and a further 3C-SiC growth was performed with a higher growth rate (90 µm/h) at a higher temperature (1600 °C) to obtain a final thickness of 150 µm. The SF presence and density were evaluated by TEM analysis performed on as-grown samples and SEM analysis on KOH etched samples with various thicknesses. A decrease of SF density was observed with an increase of 3C-SiC film thickness, with the best results (500/cm) obtained for the thickest sample. The 3C-SiC film quality and orientation was evaluated by XRD are correlated with film thickness and SF density.

We have developed and investigated the quasi-bulk crystal growth of 3C-SiC on transferred, high quality, CVD-grown templates using a sublimation sandwich related technique. The seeding layers were removed from the silicon carrier using a solution of hydrogen fluoride, nitric acid and water and glued to a substrate using carbon glue. The transferred layers were used as seeding material to grow high quality, single crystalline, DPBs free 3C-SiC crystals with thicknesses of up to 860 μm and a size of 18 x 20 mm. Analysis of the 3C-SiC layers was carried out using Laue measurement in back-reflecting geometry, Raman spectroscopy and optical microscopy.

We present a study for large defects called protrusions that form during the hetero-epitaxy of SiC on Si. We focus first on surface morphology, size, three-dimensional shape and internal structure, and second on photoluminescence and Raman features. These defects have a peculiar 3D structure similar to inverted square pyramids with a vertex close to the SiC/Si interface. The size of the square and the height of the pyramid are both related to the thickness of the epi-layer and are spatially limited by the stacking faults in the {1 1 1} planes. The inner core of the defect consists of nano crystals twinned with respect to the substrate orientation. The defects demonstrate broad peculiar emission band at about 750 nm, while the usual photoluminescence signal from band recombination is at 520 nm. The SiC/Si interface is studied in order to investigate the seed of protrusion defect formation. We found that seeds responsible for the formation of protrusions lie 10 nm above the SiC/Si interface. This indicates that protrusion forms after the carbonization process, in particular in the temperature ramp up after carbonization. Modifying the Si/C ratio and some other growth parameters in the post-carbonization process we succeed in reducing the density of protrusion to less than 10 cm−2.

Silicon carbide (SiC) is a compound semiconductor, which is considered as a possible alternative to silicon for particles and photons detection. Its characteristics make it very promising for the next generation of nuclear and particle physics experiments at high beam luminosity. Silicon Carbide detectors for Intense Luminosity Investigations and Applications (SiCILIA) is a project starting as a collaboration between the Italian National Institute of Nuclear Physics (INFN) and IMM-CNR, aiming at the realization of innovative detection systems based on SiC. In this paper, we discuss the main features of silicon carbide as a material and its potential application in the field of particles and photons detectors, the project structure and the strategies used for the prototype realization, and the first results concerning prototype production and their performance.

Silicon carbide is a very promising material for next generation nuclear physics experiments at high beam luminosity. Such activities require devices able to sustain high fluxes of particles (up to 1014 ions/cm2) in order to determine the cross sections of very rare nuclear phenomena. One of these activities is the NUMEN project, which aims, through the double charge exchange reactions, to impact in the determination of nuclear matrix elements entering in the expression of half-life of the neutrino-less double beta decay. Due to the very low cross sections, these features can just be explored at fluences which exceed by far those tolerated in state of the art solid state detectors, typically used in this kind of experiments. The SiC technology offers today an ideal response to such challenges, giving the opportunity to cope the excellent properties of silicon detectors with the radiation hardness, thermal stability and visible blindness of SiC material.

Thermal annealing plays a crucial role for healing the defectiveness in the ion implanted regions of DIMOSFETs (Double Implanted MOSFETs) devices. In this work, we have studied the effect of a double step annealing on the body (Al implanted) and the source (P implanted) regions of such devices. We found that a high temperature annealing (1750°C, 1h) followed by a lower temperature one (1500°C, 4h) is mandatory to achieve low defects concentration and good crystal quality in both the n-and p-type zones of the device.

In this review the effect of the growth process on the formation of defects in the hetero-epitaxial 3C-SiC film and the possible path for defects reduction has been reported. In our analysis of the experimental data we started from the realization of the carbonization layer, the defects at the interface and in the silicon substrate, to the growth of thin and even very thick layers. The discussion has been focalized on the growth on planar blanket Si substrates without the presence of structures or specific buffer layers. Both Chemical Vapour Deposition (CVD) and Sublimation Epitaxy (SE) processes have been reported and studied in detail.

The NUMEN project aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ), by high-accuracy measurements of Heavy Ion (HI) induced Double Charge Exchange (DCE) reaction cross sections. In particular, the (18O,18Ne) and (20Ne,20O) reactions are used as tools for β+β+ and β−β− decays, respectively. In the experiments, performed at INFN - Laboratory Nazionali del Sud (LNS) in Catania, the beams are accelerated by the Superconducting Cyclotron (CS) and the reaction ejectiles are detected the MAGNEX magnetic spectrometer. The measured cross sections are challengingly low (a few nb), being the total reaction cross section much larger (a few b), thus a high sensitivity and a large rejection capability are demanded to the experimental set-up. This limits the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. A major upgrade of the LNS facility is foreseen in order to increase the experimental yield of at least two orders of magnitude, still keeping the high sensitivity of the present set-up, making it feasible a systematic study of all the cases of interest. Frontiers technologies are going to be developed, to this purpose, for the accelerator and the detection systems. In parallel, advanced theoretical models are being developed in order to extract the nuclear structure information from the measured cross sections.

In this work an extended study of the carbonization process of the silicon surface and of a low temperature transition layer in the temperature rump on the 3C-SiC epitaxial growth has been reported. It has been observed that increasing the C/H 2 ratio the voids density decreases, the thickness of the carbonization layer and the density increase and the morphology improves. The low temperature transition layer, grown during the ramp between the carbonization step and the real growth process, produce a further reduction of the voids at the 3C-SiC/Si interface and a considerable reduction of the stress of the 3C-SiC film. This stress reduction is related to a large change of the film morphology. No effect of the interface silicon layer on the stress is observed. This study has shown the complex connection between the first steps of the 3C-SiC growth process and the properties of the film in term of stress and superficial morphology. The residual stress has important implications with regard to the processing (wafer bow) and quality of the epitaxy. Residual stress also changes the mechanical response and/or the resonant frequency of the thin-film structure and may degrade the performance in MEMS-based devices. Therefore, a better understanding of the stress relaxation mechanism could improve the performances of 3C-SiC devices and sensor technologies.

Preliminary results of 150mm SiC 4H 4°off have been obtained with the new 150mm automatic horizontal hot wall reactor PE1O6, using chlorinated chemistry (SiHCl3 + C2H4). A new injection system has been tested in two configurations and results will be shown in this paper. AFM surface roughness measurements and epi defect density have been reported.

In this paper we investigate the role of the growth rate (varied by changing the Si/H2ratio and using TCS to avoid Si droplet formation) on the surface roughness (Rq), the density of single Shockley stacking faults (SSSF) and 3C-inclusions (i.e. epi-stacking faults, ESF). We find that optimized processes with higher growth rates allow to improve the films inallthe considered aspects. This result, together with the reduced cost of growth processes, indicates that high growth rates should always be used to improve the overall quality of 4H-SiC homoepitaxial growths. Furthermore we analyze the connection between surface morphology and density of traps (Dit) at the SiO2/SiC interface in fabricated MOS devices finding consistent indications that higher surface roughness (step-bunched surfaces) can improve the quality of the interface by reducing theDitvalue.

The thermal evolution of defects induced in 4H–SiC by multiple implantation of C ions was investigated by Low Temperature Photoluminescence in the temperature range 450–1000 K. The photoluminescence spectra show sharp luminescent lines (alphabet lines) in the wavelength range 426–440 nm upon irradiation and thermal treatment at 450 K induces the appearance of a new line at 427 nm ( D I centre). The trend shown by the luminescence lines as a function of the temperature is quite complex. The alphabet lines intensity increases up to 850 K, whereas at higher temperature decreases with an activation energy of 2.0 eV, suggesting that the defect, responsible for these lines, is the Si-vacancy. The luminescence yield of D I centre is always increasing as a function of the temperature, with a higher slope from 750 K, suggesting a correlation to the reconfiguration and to the annealing of point defects.

Point defects induced in SiC by ion irradiation show a recombination at temperatures as low as 320 K and this process is enhanced after running current density ranging from 80 to 120 A/cm 2 . Ion irradiation induces in SiC the formation of different defect levels and low-temperature annealing changes their concentration. Some levels ( S 0 , S x and S 2 ) show a recombination and simultaneously a new level ( S 1 ) is formed. An enhanced recombination of defects is besides observed after running current in the diode at room temperature. The carriers introduction reduces the S 2 trap concentration, while the remaining levels are not modified. The recombination is negligible up to a current density of 50 A/cm 2 and increases at higher current density. The enhanced recombination of the S 2 trap occurs at 300 K, which otherwise requires a 400 K annealing temperature. The process can be related to the electron–hole recombination at the associated defect.

The defects produced by 7.0 MeV C + irradiation in 4H-SiC epitaxial layer were followed by Deep Level Transient Spectroscopy, current-voltage measurements and Transmission Electron Microscopy in a large fluence range (10 9-5?ó10 13 ions/cm 2). At low fluence (10 9 -10 10 ions/cm 2), the formation of three main level defects located at 0.68 eV, 0.98 eV and 1.4 eV below the conduction band edge is detected. The trap concentration increases with ion fluence suggesting that these levels are associated to the point defects generated by ion irradiation. In this fluence range the leakage current of the diodes does not change. At higher fluence an evolution of defects occurs, as the concentration of traps at 0.68 eV and 1.4 eV decreases, while the intensity of the level at 0.98 eV remains constant. In this fluence range complex defects are formed and an increase of a factor five in the leakage current is measured. ¬© (2009) Trans Tech Publications.

We have developed a high-quality growth process for 3C-SiC on on-axis (111)Si substrates with the ultimate goal to demonstrate high quality and yield electronic and MEMS devices. A single-side polished 50 mm (111)Si wafer was loaded into a hot-wall SiC CVD reactor for growth. The 3C-SiC process was performed in two stages: carbonization in propane and hydrogen at 1135°C and 400 Torr followed by growth at 1380°C and 100 Torr. X-ray diffraction rocking curve analysis of the 3C-SiC(222) peak indicates a FWHM value of 219 arcsec. This is a very interesting result given that the film thickness was only 2 µm, thus indicating that the grown film is of very high quality compared with published literature values. X-ray polar figure mapping was performed and it was observed that the micro twin content was below the detection limit. Therefore TEM characterization was performed in plan view to allow assessment of the stacking fault density as well as confirmation of the very low micro twin concentration in this film. TEM analysis indicates a low concentration of stacking faults in the range of 104 cm-1.

The low temperature evolution of point defects induced in SiC by ion irradiation was investigated by deep level transient spectroscopy. The defects were introduced by irradiation with a 7.0 MeV beam of C+ ions at a fluence of 6 × 109 cm− 2. Annealing was then performed in the temperature range of 330–400 K in order to study the change in point defect structure with temperature. The low temperature annealing performed was observed to induce a change in the produced defects. The deep levels related to the Sx (EC − 0.6 eV) and S2 defects (EC − 0.7 eV) recovered with annealing while, simultaneously, a new level, S1 (EC − 0.4 eV), was formed. The activation energy of the S1 defect is 0.94 eV, while the annealing of both the Sx and S2 levels occurred with activation energy of 0.65 eV.

The defects produced by irradiation with 7 MeV C+ induce a change in the electrical properties of 4H-SiC Schottky diodes. Capacitance-voltage and Current-voltage characteristics of the diodes fabricated in epilayers doped with different nitrogen concentrations were monitored before and after irradiation with different fluences. The Capacitance-voltage curves show free carrier compensation after low fluence irradiation and it was found that the reduction of carriers per ion induced vacancy increases with nitrogen content. The forward current-voltage characteristics of the diodes show an increase in the series resistance after irradiation. This change is mainly related to the high compensation occurring around the end of the ion range.

High growth rate of 4H-SiC epitaxial layers can be reached with the introduction of HCl in the deposition chamber. The effect of the Cl/Si ratio on this epitaxial growth process has been studied by optical and electrical measurements. Optical microscopy shows an improvement of the surface morphology and luminescence measurements reveal a decrease of epitaxial layer defects with increasing the Cl/Si ratio in the range 0.05–2.0. The leakage current measured on the diodes realized on these wafers is reduced of an order of magnitude and DLTS measurements show a decrease of the EH6,7 level concentration in the same range of Cl/Si ratio. The value Cl/Si=2.0 allows to grow epitaxial layers with the lowest defect concentration.

We present a process to transfer CVD grown heteroepitaxial 3C-SiC on Si onto polycrystalline SiC, involving an etching step to get rid of the Si and a homogeneous carbon glue deposit, facilitating the resulting compound to be used as a seeding material for further growth process. In a sublimation sandwich setup, realized within an inductively heated physical vapor transport reactor, used for bulk growth of SiC, the thickness of the 3C-SiC seed was increased up to 850 μm while keeping the cubic polytype. With the introduction of Ta as a carbon getter, the gas phase composition is optimized in order to achieve an improved growth front. Single crystalline growth is confirmed by Laue diffraction and Raman measurements. The Raman peaks are shifted to higher wavenumbers, indicating compressive stress in the grown samples. Furthermore, a scale up of the process is demonstrated, showing the feasibility of growing 3C-SiC on an area of 10.5 cm2 in a 2 inch setup featuring a thickness of approximately 570 μm.

We study the correlation between crystal quality and electrical transport in 4H-SiC by micro-photoluminescence and laser-beam-induced photocurrent measurements. A focused HeCd laser at 325 nm has been employed to simultaneously measure, with a spatial resolution of a few microns, both the photoluminescence and current–voltage characteristics of 4H-SiC Schottky diodes. We found that the laser-induced photocurrent acquired along a defect can give information on its spatial distribution in depth and that the local minority carrier lifetime and generation depend on the type of stacking fault, both decreasing for defects with deeper intragap levels.

Low-temperature (40 K) photoluminescence (PL) measurements were used to follow the defect formation induced in the 4H-SiC epitaxial layer by irradiation with 200 keV H+ and 800 keV C+ in the fluence range of 5×109–3.5×1012 ions/cm2. After irradiation, the PL spectra show the formation of some sharp lines, called “alphabet lines”, located in the wavelength range of 425–443 nm, due to the recombination of excitons at structural defects induced by ion beams. The analysis of luminescence line intensity versus ion fluence allows us to mark two different groups of peaks, namely the P1 group (e, f and g lines) and the P2 group (a, b, c and d lines). The normalised yield of P1 group lines increases with ion fluence and reaches a maximum value, while the normalised yield of P2 group lines exhibits a threshold fluence and then increases until a saturation value is reached. These different trends indicate that, while the P1 group lines are related to the primary defects created by ion beams (interstitial defects, va...

A simple and effective approach to fabricate extensive 3D ZnO nanoarchitectures on alkaline etched (100) Si substrates is presented. Textured silicon micropattern drives ZnO 1D growth on all the {111} exposed faces, resulting in sea sponge-likeZnO nanoarchitectures. The obtained 3D nanostructured ZnO is the result of a perfectly ordered array of continuous and crystalline ZnO nanorods, grown on the silicon pyramid {111} faces. The substrate orientation and the relative roughness, intrinsically derived by the alkaline silicon texturization, drive the preferential growth of one-dimensional ZnO nanorods. The ZnO nanorods photoluminescence spectra show, at room temperature, a narrow ultraviolet (UV) emission peak at 3.28 eV and a broad unstructured green band emission at 2.57 eV. These luminescence emissions are attributed to the near band-edge exciton transitions and to the defect emission, respectively. This original approach to fabricate high surface area ZnO nanoarchitectures presents the advantages of well established and reproducible methodologies of semiconductors industrial manufacturing (silicon micromachining and chemical vapor deposition), thus representing an easy scaling up solution to fabricate new ZnO-based nanomaterials.

The changes in the electrical properties of 4H-SiC epitaxial layer induced by irradiation with 7.0 MeV C+ ions were investigated by current-voltage measurements and deep level transient spectroscopy (DLTS). Current-voltage characteristics of the diodes fabricated from epilayers doped with different nitrogen concentrations were monitored before and after irradiation in the fluence range of 109–1010 cm−2. The leakage current was not changed after irradiation, while the forward current-voltage characteristics of the diodes showed an increase in the series resistance, which is mainly related to the high degree of compensation occurring near the end of the ion implant depth.The temperature dependence of the carrier mobility determined from the I-V measurements in the temperature range of 100–700 K shows a T−3 dependence of mobility as determined from the nonirradiated as well as the irradiated diodes. DLTS measurements of the irradiated diodes reveal the presence of two deep levels located at 0.98 and 1.4 eV below the conduction band edge.

The introduction of hydrogen chloride (HCl) in the deposition chamber during the growth of 4H-SiC epitaxial layers allows very high growth rates to be achieved. The properties of the epilayers and the growth rate depend on many parameters such as the growth temperature and the C/Si, Cl/Si, and Si∕H2 ratios. We have used optical and electrical measurements to investigate the effect of the Cl/Si and Si∕H2 ratio and growth temperature on the epitaxial growth process. The growth rate increases with increasing Si∕H2 ratio and higher growth rates are obtained when HCl is added to the gas flow. Optical microscopy shows an improvement of the surface morphology, and luminescence measurements reveal a decrease in the concentration of complex defects with increasing Cl/Si ratio in the range of 0.05–2.0 and with increasing growth temperature from 1550 °C to 1650 °C. The electrical measurements on the diodes realized on these epitaxial layers show a decrease of the leakage current with increasing Cl/Si ratio and growt...

Neutrinoless double beta decay (0{\nu}\b{eta}\b{eta}) is considered the best potential resource to determine the absolute neutrino mass scale. Moreover, if observed, it will signal that the total lepton number is not conserved and neutrinos are their own anti-particles. Presently, this physics case is one of the most important research beyond Standard Model and might guide the way towards a Grand Unified Theory of fundamental interactions. Since the \b{eta}\b{eta} decay process involves nuclei, its analysis necessarily implies nuclear structure issues. The 0{\nu}\b{eta}\b{eta} decay rate can be expressed as a product of independent factors: the phase-space factors, the nuclear matrix elements (NME) and a function of the masses of the neutrino species. Thus the knowledge of the NME can give information on the neutrino mass scale, if the 0{\nu}\b{eta}\b{eta} decay rate is measured. In the NURE project, supported by a Starting Grant of the European Research Council, nuclear reactions of double charge-exchange (DCE) will be used as a tool to extract information on the \b{eta}\b{eta} NME. In DCE reactions and \b{eta}\b{eta} decay, the initial and final nuclear states are the same and the transition operators have similar structure. Thus the measurement of the DCE absolute crosssections can give crucial information on \b{eta}\b{eta} matrix elements., Comment: arXiv admin note: substantial text overlap with arXiv:2001.09657; text overlap with arXiv:2001.09648