Nonionizing Energy Loss Research Articles

Energy-loss process in Ni63 betavoltaic batteries

The betavoltaic effect is characterized by multiple random scatterings and high energy density exchange. The conversion of beta-particles’ energy to electric current is a sophisticated process. A GEANT4-based code is used to model the energy-loss mechanisms of emitted electrons from 63Ni radioisotope, considering the physics behind these losses (such as Coulomb scattering, nuclear stopping, and Bethe-Bloch theory) while taking into account self-absorption and backscattering factors. The study indicates the existence of a significant non-ionizing energy-loss of penetrating beta-particles that may stimulate remarkable local heating in the absorbing structure, which results in a degradation in the performance of betavoltaic batteries using 63Ni as nuclear fuel

Study of Neutron-, Proton-, and Gamma-Irradiated Silicon Detectors Using the Two-Photon Absorption-Transient Current Technique.

The Two-Photon Absorption-Transient Current Technique (TPA-TCT) is a device characterisation technique that enables three-dimensional spatial resolution. Laser light in the quadratic absorption regime is employed to generate excess charge carriers only in a small volume around the focal spot. The drift of the excess charge carriers is studied to obtain information about the device under test. Neutron-, proton-, and gamma-irradiated p-type pad silicon detectors up to equivalent fluences of about 7 × 1015 neq/cm2 and a dose of 186 Mrad are investigated to study irradiation-induced effects on the TPA-TCT. Neutron and proton irradiation lead to additional linear absorption, which does not occur in gamma-irradiated detectors. The additional absorption is related to cluster damage, and the absorption scales according to the non-ionising energy loss. The influence of irradiation on the two-photon absorption coefficient is investigated, as well as potential laser beam depletion by the irradiation-induced linear absorption. Further, the electric field in neutron- and proton-irradiated pad detectors at an equivalent fluence of about 7 × 1015 neq/cm2 is investigated, where the space charge of the proton-irradiated devices appears inverted compared to the neutron-irradiated device.

Simulation of irradiation damage in CsPbI3-based perovskite solar cells by energetic protons

Perovskite solar cells are emerging as one of the most promising energy sources for space applications. However, the displacement damage of solar cells in the space environment has gradually deteriorated their performance. In this work, the depth distribution of primary knocked-on atoms (PKA), non-ionizing energy loss and defect concentration of CsPbI3-based perovskite solar cells irradiated by 0.1–2000 MeV protons have been simulated by the Geant4 toolkit. It is found that the PKA yield shows an obvious step behavior near the layer boundary of the solar cell, and that the electron and hole transport layers have the high defect concentration whereas the CsPbI3-based perovskite layer owns the least PKA yield. In particular, in the geostationary orbit, the radiation damage effect caused by space protons to the solar cells is approximately equivalent to that irradiated by 0.18 MeV protons, which provides a good reference for ground irradiation experiments for CsPbI3-based perovskite solar cells.

Radiation tolerance of the MUX64 for the High Granularity Timing Detector of ATLAS

The MUX64 ASIC is a 64-to-1 analog multiplexer to accommodate 64 inputs, with one addressed to output for ADC readout. It is developed for monitoring of the Low-Gain Avalanche Detectors (LGAD) detector modules in the High Granularity Timing Detector (HGTD) of the ATLAS Phase-II upgrade. The MUX64 chips will be used in the radiation field of high-luminosity pp collisions at LHC to an integrated luminosity of 4000 fb-1. This work presents the radiation tolerance study for the MUX64 being tested with 80 MeV protons and X-ray exposures for damages caused by Non-Ionizing Energy Loss (NIEL) and Total Ionizing Dose (TID), respectively. The irradiated samples demonstrated tolerance to the NIEL to a fluence of 3.21 × 1015 (Si, 1 MeV) neq/cm2, and the TID of 7.46 × 105 Gy (Si).

Degradation of electrical performance and radiation damage mechanism of cascode GaN HEMT with 80 MeV proton

In this paper, proton irradiations on Cascode GaN HEMT power device with an energy of 80 MeV and fluences of 2 × 1011 p/cm2 and 6 × 1011 p/cm2 have been carried out, where the threshold voltages drifted negatively by 20.55% and 28.17%, respectively. After two months of room temperature annealing, the threshold voltages recovered 0.22 V and 0.27 V, respectively. The ionizing deposition energy (IEL) was simulated by using Monte Carlo software and TCAD, it the results showed that the value of IEL in Si MOSFET is 5 ∼ 6 orders higher than that in GaN HEMT, while the value of the non-ionizing energy loss (NIEL) is one order higher than that in GaN HEMT. It means that the proton irradiation on the Cascode depleted GaN HEMT is more prone to produce displacement damage. As a large number of electrons and holes pairs were existed on the incident path of Si MOSFET under the proton irradiation, the produced electron will be captured by the gate oxide traps at the SiO2/Si interface, and the holes be captured by the defects generated in displacement damage, resulting in the accumulation of oxide trapped charges. Then, the electrical performance of Si MOSFET degrades seriously, thereby affecting the performance of the entire device. The studies will be helpful for the radiation hardening of Cascode GaN HEMT.

Geant4 simulation of Hg<sub>1–<i>x</i></sub>Cd<sub><i>x</i></sub>Te infrared focal plane array image sensor space proton displacement damage and total ionizing dose effects

A large-format, high-resolution Hg<sub>1–<i>x</i></sub>Cd<sub><i>x</i></sub>Te infrared focal plane array (IRFPA) image sensor can be used in aerospace remote sensing and high-precision satellite imaging. The next generation of meteorological satellites in China will all adopt this type of image sensor. However, space high-energy protons can cause displacement damage effects in Hg<sub>1–<i>x</i></sub>Cd<sub><i>x</i></sub>Te IRFPA detectors and induce total ionizing dose (TID) effects in the pixel unit metal-oxide-semiconductor (MOS) transistors. This study focuses on a 55nm manufacturing process Hg<sub>1–<i>x</i></sub>Cd<sub><i>x</i></sub>Te IRFPA sensor widely used in image sensors by using a 2 pixel×2 pixel basic pixel unit model for large-format arrays and constructing a Geant4 simulation model. Simulations are conducted for different proton irradiation fluences, including 10<sup>10</sup>, 10<sup>11</sup>, 10<sup>12</sup> and 10<sup>13</sup> cm<sup>–2</sup>. The results show the displacement damage under various fluences, including non-ionizing energy loss and displacement atom distribution. It is found that at a proton cumulative fluence of 10<sup>13</sup> cm<sup>–2</sup>, in addition to considering the displacement damage effect in the Hg<sub>1–<i>x</i></sub>Cd<sub><i>x</i></sub>Te IRFPA sensor, attention must also be paid to the TID effects on the MOS transistors in the pixel units. Additionally, this study provides a preliminary assessment of the damage conditions in the space environment based on simulation results. This study provides crucial data for supporting the space applications of future large-format Hg<sub>1–<i>x</i></sub>Cd<sub><i>x</i></sub>Te IRFPA image sensors.

Probing the Interfacial Properties of ACIGS Solar Cells with Targeted Proton Irradiation

ACIGS solar cells are exposed to targeted radiation to probe the front and back interfaces of the absorber to assess the impact of space environments on these systems. These data suggest ACIGS cells are more radiation‐hard than early CIGS devices likely due to the lower defect densities and more ideal interfaces in the ACIGS system. A combination of J–V and external quantum efficiency measurements indicates some improvement in the performance of the device due to the effects of local heating in the dominant ionizing electronic energy loss regime of proton irradiation that anneal the upper CdS/ACIGS interface. However, nonionizing energy losses at the base of the solar cell also appear to inhibit minority carrier collection from the back of the cell at the ACIGS/Mo interface, which is discussed in terms of defect‐mediated changes in the doping profile, the Ga/Ga+In ratio, and impurity composition after proton irradiation.

Radiation effects model for Ultra-Thin Silicon Solar Cells

This work is focused on investigation of radiation effects in Ultra-Thin Silicon solar cells with a particular emphasis on electron irradiation. The study is motivated by the application of these solar cells, developed by Solestial, Inc., for powering space missions, including those led by NASA, the Department Of Defence (DOD), and commercial satellite missions. Our research encompasses both experimental and theoretical approaches, addressing unique challenges posed by ultra-thin solar cell technology that deviates from the traditional models. From the experimental point of view, the test structures were irradiated with 1 MeV electrons up to the fluence of 1E+15 e/cm 2. Radiation effects due to accumulated electron dose were noticed as a drop in open-circuit voltage (Voc ). An analytical expression for modeling the Voc characteristic of the UT-Si cell after exposure to electron irradiation was formulated and subsequently compared with experimental data. The theoretical foundation of the proposed approach builds upon the Non-Ionising Energy Loss (NIEL) concept, a fundamental parameter in addressing radiation damage modelling and survivability predictions.

Application of displacement damage dose approach to low-energy proton irradiated GaInP/GaAs/Ge solar cells

In this paper, a displacement damage simulation model for proton-irradiated GaInP/GaAs/Ge triple junction (TJ) solar cells is constructed in Geant4, and the problem of the displacement damage dose curve deviation for low-energy protons is analyzed. The modeling results show that energy loss effects and local displacement damage are important factors for the deviation of the displacement damage dose curve. The non-ionizing energy loss (NIEL) values of GaAs sub-cells calculated by Geant4 can effectively improve the deviation of the curve caused by energy loss effects. The NIEL should be constrained by the structure and size of the device rather than just the proton energy and material type. In addition, the isotropic radiation field numerical method proposed in this paper allows the displacement damage simulation model constructed in Geant4 to be expediently applied to the radiation environment in space.

Radiation tolerance and self-healing in triple halide perovskite solar cells

The high tolerance and stability of triple halide perovskite solar cells is demonstrated in practical space conditions at high irradiation levels. The solar cells were irradiated for a range of proton energies (75 keV, 300 keV, and 1 MeV) and fluences (up to 4 × 1014 p/cm2). The fluences of the energy proton irradiations were varied to induce the same amount of vacancies in the absorber layer due to non-ionizing nuclear energy loss (predominant at <300 keV) and electron ionization loss (predominant at >300 keV). While proton irradiation of the solar cells initially resulted in degradation of the photovoltaic parameters, self-healing was observed after two months where the performance of the devices was shown to return to their pristine operation levels. Their ability to recover upon radiation exposure supports the practical potential of perovskite solar cells for next-generation space missions.

Carrier removal rates in 4H–SiC power diodes – A predictive analytical model

An analytical model for predicting the proton and neutron radiation-induced carrier removal in silicon carbide (4H–SiC) diodes, is developed. It is primarily aimed towards a fast calculation of the carrier removal rates (ηe) and critical fluence (above which the diode drift layer is fully compensated), for a wide range of particle energies and diode ratings. The model utilizes the NIEL (non-ionizing energy loss) concept along with the actual carrier removal rate values for SiC available in the literature. A comparison to Si power devices is also made. The results from the predictive model suggest that diodes with a lower voltage rating can sustain a higher particle fluence and displacement damage before their drift layers are fully compensated. This provides radiation hardening guidelines for 4H–SiC power diodes at a device engineering level, which can help improve the reliability of circuits in harsh environment applications, such as space. The model is validated through TCAD simulations incorporating the proton-induced defects, as well as experimentally by irradiating SiC diodes with 2 MeV protons. The extracted compensation levels are in good agreement with those predicted by the analytical model, validating its potential in predicting carrier removal rate of SiC diodes for radiation prone environments.

Neutron Displacement Damage Cross Section in GaN: Numerical Evaluations and Differences With Si

The displacement damage cross-section of the neutron - GaN interaction is calculated in the energy range from meV to GeV. Different calculation methods are used and discussed to estimate the modeling uncertainty. The Non-Ionizing Energy Loss (NIEL) and the relative damage factors are also deduced. Differences with the neutron - Silicon interactions are presented and the impacts on the estimation of Total Non-Ionizing Dose (TNID) levels are evaluated as a function of neutron energy.

Single Event Displacement Effects in a VLSI

The research results of single event displacement effects in VLSI elements under the effect of neu-tron radiation are presented. The nonionizing energy losses in a sensitive microvolume of a VLSI element for the interaction of neutrons with silicon atoms are estimated. The influence of individual disordered regions and clusters of radiation defects on the performance of VLSIs are determined. The possibilities of fast anneal-ing effects and the additive effects of increasing the reverse p–n junction currents of individual VLSI elements on the conditions for the occurrence of failures of the entire microcircuit are shown.

Proton irradiation effects on GaInP/GaAs/Ge triple junction cells

GaAs solar cells, with a higher transfer efficiency, is regarded as a good candidate for the space applications. For the better applications to the deep space exploration, it is necessary to explore its irradiation effects. Here, the effects of irradiation energy and irradiation fluence on the degradation of solar cells were studied, and the results show that proton irradiation with a fluence of 5 × 1011/cm2 has slightly effect on the performance the cell, with further increasing fluence the quantum efficiency decreases; and the degradation of quantum efficiency is manly from long wavelength band, meaning that the displacement damage mainly occurs in middle-junction GaAs cells under relatively higher fluence of proton irradiation. In comparison with the irradiation fluence, the effects of the irradiation energy on the degradation to GaInP cell and GaAs sub-cell are relatively weaker. Non-ionizing energy loss and TCAD simulations were carried out to explain the mechanism behind.

Evaluation of HPK [formula omitted] planar pixel sensors for the CMS Phase-2 upgrade

To cope with the challenging environment of the planned high luminosity upgrade of the Large Hadron Collider (HL-LHC), scheduled to start operation in 2029, CMS will replace its entire tracking system. The requirements for the tracker are largely determined by the long operation time of 10 years with an instantaneous peak luminosity of up to 7.5 × 1034cm−2s−1 in the ultimate performance scenario. Depending on the radial distance from the interaction point, the silicon sensors will receive a particle fluence corresponding to a non-ionising energy loss of up to Φeq= 3.5 × 1016cm−2. This paper focuses on planar pixel sensor design and qualification up to a fluence of Φeq = 1.4 × 1016cm−2.For the development of appropriate planar pixel sensors an R&D program was initiated, which includes n+-p sensors on 150mm (6”) wafers with an active thickness of 150µm with pixel sizes of 100×25 µm2 and 50×50 µm2 manufactured by Hamamatsu Photonics K.K. (HPK). Single chip modules with ROC4Sens and RD53A readout chips were made. Irradiation with protons and neutrons, as well was an extensive test beam campaign at DESY were carried out. This paper presents the investigation of various assemblies mainly with ROC4Sens readout chips. It demonstrates that multiple designs fulfil the requirements in terms of breakdown voltage, leakage current and efficiency. The single point resolution for 50×50 µm2 pixels is measured as 4.0µm for non-irradiated samples, and 6.3µm after irradiation to Φeq = 7.2 × 1015cm−2.

Annealing effects on Cu(In,Ga)Se2 solar cells irradiated by high-fluence proton beam

Radiation tolerance of Cu(In,Ga)Se2 (CIGS) solar cells has been investigated using high-fluence proton beam irradiation for application to devices in extremely-high-radiation environments. CIGS solar cells deteriorated after high-energy proton irradiation with non-ionizing energy loss of 1 × 1016 MeVneq cm−2, however, the CIGS solar cells could generate power after high-fluence irradiation. The ideality factors increased from 1.3 to 2.0, and series resistance increased, indicating that the concentration of recombination centers increased in CIGS layers. After heat-light annealing, the conversion efficiencies gradually recovered, and the recombination centers were confirmed to be partly passivated by annealing at 90 °C. The short-circuit currents for 10 μm thick CIGS solar cells were recovered by dark annealing in the same manner as for 2 μm thick CIGS solar cells. Dark annealing on irradiated CIGS solar cells has beneficial effects on passivate the recombination centers, even using thicker CIGS layers.

Proton-Induced Displacement Damages in 2-D and Stacked CMOS SPADs: Study of Dark Count Rate Degradation

Dark count rate (DCR) degradation is measured on 40-nm 2D and stacked CMOS SPADs after proton irradiations. Mean DCR increase is plotted for different displacement damage doses (DDD) for two biasing conditions. Due to field enhancement effects such as Poole-Frenkel and phonon-assisted-tunneling, Non-Ionizing Energy Loss (NIEL) scaling is found to be dependent on the excess bias. Moreover, the associated damage factors are higher compared to pixels with unity gain photodiodes. A model predicting DCR increase with DDD based on field enhancement factor equations and damage energy deposited by the proton induced recoil spectrum is established and fits well with experimental data. Finally, activation energies are extracted: low values between 25 °C and 60 °C confirm the domination of field effects over thermal generation. Furthermore, large energy discrepancies seen at a fixed DCR increase are suggesting that defect structures could also have an impact on DCR distributions.

Impact of neutron irradiation on electronic carrier transport properties in Ga2O3 and comparison with proton irradiation effects

The minority charge carrier transport in beta gallium oxide (-Ga2O3) before and after exposure to neutrons from a 241Am-Be source was studied. Cathodoluminescence (CL) spectroscopy and current–voltage (I-V) characteristics were used to study minority carrier behavior. High energy radiation affects minority carrier properties through the production of carrier traps that reduce the conductivity and mobility of the material. In this paper, we report the effects of neutron radiation in silicon-doped -Ga2O3, using rectifiers or transistors as the measurement platform. The thermal activation energy of the reference (non-irradiated) sample was 40.9 meV, which is ascribed to silicon-donors. CL measurements indicate a slightly indirect bandgap energy of 4.9 eV. Neutrons create disordered regions in -Ga2O3 rather than just point defects, resulting in the lowest carrier removal rate because of the lowest average non-ionizing energy loss. The neutron irradiation caused an increase in reverse bias leakage current in rectifiers and a carrier removal rate of 480 cm−1 but had little effect on reverse recovery switching time. Differences in CL spectra were observed between vertical and lateral device structures, emphasizing the importance of impurities and defects in the starting material. The neutron energies in the Am-Be source range up to 11 MeV, with an average energy between 4 and 5 MeV (Figure 1). We also contrasted neutron damage with the effects of irradiation with 10 MeV protons. Under 10 MeV proton irradiation, the thermal activation energies increase. This is attributable to high order defects and their influence on carrier lifetimes. The measurements show that -Ga2O3 is more resistant to radiation damage than other wide bandgap semiconductors due to its higher displacement threshold energy, which is inversely proportional to the lattice constant.

Proton induced radiation effect of SiC MOSFET under different bias

Radiation effects of silicon carbide metal–oxide–semiconductor field-effect transistors (SiC MOSFETs) induced by 20 MeV proton under drain bias (V D = 800 V, V G = 0 V), gate bias (V D = 0 V, V G = 10 V), turn-on bias (V D = 0.5 V, V G = 4 V) and static bias (V D = 0 V, V G = 0 V) are investigated. The drain current of SiC MOSFET under turn-on bias increases linearly with the increase of proton fluence during the proton irradiation. When the cumulative proton fluence reaches 2 × 1011 p⋅cm−2, the threshold voltage of SiC MOSFETs with four bias conditions shifts to the left, and the degradation of electrical characteristics of SiC MOSFETs with gate bias is the most serious. In the deep level transient spectrum test, it is found that the defect energy level of SiC MOSFET is mainly the ON2 (E c – 1.1 eV) defect center, and the defect concentration and defect capture cross section of SiC MOSFET with proton radiation under gate bias increase most. By comparing the degradation of SiC MOSFET under proton cumulative irradiation, equivalent 1 MeV neutron irradiation and gamma irradiation, and combining with the defect change of SiC MOSFET under gamma irradiation and the non-ionizing energy loss induced by equivalent 1 MeV neutron in SiC MOSFET, the degradation of SiC MOSFET induced by proton is mainly caused by ionizing radiation damage. The results of TCAD analysis show that the ionizing radiation damage of SiC MOSFET is affected by the intensity and direction of the electric field in the oxide layer and epitaxial layer.

Effect of electronic stopping in molecular dynamics simulations of collision cascades in gallium arsenide

Understanding the generation and evolution of defects induced in matter by ion irradiation is of fundamental importance to estimate the degradation of functional properties of materials. Computational approaches used in dierent communities, from space radiation eects to nuclear energy experiments, are based on a number of approximations that, among others, traditionally neglect the coupling between electronic and ionic degrees of freedom in the description of displacements. In this work, we study collision cascades in GaAs, including the electronic stopping power for selfprojectiles in dierent directions obtained via real time Time Dependent Density Functional Theory in Molecular Dynamics simulations of collision cascades, using the recent electron-phonon model and the previously developed two-temperature model. We show that the former can be well applied to describe the eects of electronic stopping in molecular dynamics simulations of collision cascades in a multielement semiconductor and that the number of defects is considerably aected by electronic stopping eects. The results are also discussed in the wider context of the commonly used non-ionizing energy loss model to estimate degradation of materials by cumulative displacements.