This study investigates the effects of space environmental radiation on the performance of In 0.53 Ga 0.47 As Quadrant Photodiodes (QPDs) and assesses their suitability for the Laser Interferometer Space Antenna (LISA) mission. QPDs of 1.0 mm, 1.5 mm, and 2.0 mm diameter were irradiated with 20 and 60 MeV protons, 0.5 and 1 MeV electrons, and Co 60 gamma rays. An exposure corresponding to a Displacement Damage Equivalent Fluence (DDEF) of 1.0×10 +12 p/cm² for 20 and 60 MeV protons and a total ionising dose of 237 krad were applied, exceeding the radiation requirements for the LISA mission by a factor of approximately five. Experiments were conducted to measure changes in QPD dark current, capacitance, and responsivity. The QPDs were integrated with a low-noise DC-coupled transimpedance amplifier to form the Quadrant Photoreceiver (QPR). QPR noise and performance in an interferometric system like LISA were also performed. Although radiation impacted their dark current and responsivity, almost all QPDs met LISA’s validation criteria and did not demonstrate any critical failure. These findings suggest that the tested QPDs are promising candidates for LISA and other space-based missions.

This study investigates the use of atomic layer deposition (ALD) to mitigate multipacting phenomena inside superconducting radio frequency cavities used in particle accelerators while preserving high quality factors in the 1010 range. The unique ALD capability to control the film thickness down to the atomic level on arbitrary complex shape objects enables the fine-tuning of TiN film resistivity and total electron emission yield (TEEY) from coupons to devices. This level of control allows us to adequately choose a TiN film thickness that provides both high resistivity to prevent Ohmic losses and a low TEEY to mitigate multipacting for the application of interest. The methodology presented in this work can be scaled to other domains and devices subject to RF fields in vacuum and sensitive to multipacting or electron discharge processes with their own requirements in resistivities and TEEY values.

The nonionizing energy loss (NIEL) commonly used to assess the displacement damage dose (DDD) effects in irradiated devices and materials is based on the definition of single atomic displacement threshold energy (E-d). The use of a single E-d value is known to reproduce quite poorly the level of damage induced by electrons. A method to include a damage threshold energy distribution in the calculation of the NIEL is reported. The variability of displacement threshold energies linked to crystallographic anisotropy of the solids is indirectly taken into account. It also enables the Lindhard partition function to be more consistent with both molecular dynamics (MDs) modeling and experimental measurements. Below similar to 1 MeV, our calculations change significantly the electron's NIEL, that better match experimental damage factors. The NIEL of protons, for its part, is affected at lower energy (<1 keV).

This work presents the SEU responses of four SRAM devices (65nm, 40nm, 28nm and 16nm) measured at different angles of incidence and orientation of the device in respect to the low energy proton beam direction. Experimental data are discussed with the support of multi-physics and multi-scale simulations. Difference of one order of magnitude is observed for SRAMs irradiated between the different directions the beam is entering the device. The conclusions drawn from the simulation results suggesting that the difference in the SEU cross section could be attributed to the charge sharing between the N and P wells of the two inverters of the SRAM bit. The consequent feedback reduces the overall ionization effects in the SRAM cell when exposed to low energy protons.

The displacement damage cross section of the neutron–GaN interaction is calculated in the energy range from millielectronvolts to gigaelectronvolts. Different calculation methods are used and discussed to estimate the modeling uncertainty. The nonionizing 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 nonionizing dose (TNID) levels are evaluated as a function of neutron energy.

In this work, we have made experimental measurements of multiple-hump total electron emission yield (TEEY) curves on SiO2 thin films. A Monte-Carlo electron transport model, published in Gibaru et al., J. Electron Spectrosc. Relat. Phenom. 261, 147265 (2022), has been developed to analyze the physical reasons of such atypical behavior. It is shown that the multiple-hump TEEY curves of thin dielectric layers are due to internal recombination effects. However, such kind of phenomenon is demonstrated to be strongly correlated to the incident current density. This analysis reveals that the double-hump TEEY curves observed commonly on insulators are also most probably a measurement artifact, tied to the operating parameters of the electron gun. A careful choice of experimental parameters can eliminate this artifact, by using a constant current density that is also low enough to limit recombination effects.

Low energy electrons up to some keV may cause Multipactor breakdowns in RF devices [1] , driven by the Electron Emission Yield (EEY) of the materials. Insulators are often found in these components, however they can increase the multipactor effect or be subject to dielectric breakdown. Hence the knowledge of the EEY and charge buildup in insulators is crucial.

The electron emission yield (EEY) is defined as the ratio between the total number of emitted electrons and the total number of incident electrons. The knowledge of the EEY is required in many applications dealing with plasma-wall interactions and electron trigging discharge: hall thruster technology, multipactor discharge, space radiation induced electric charging, etc.

This work presents comparisons between numerical simulations and secondary electron emission yield mea-surements. The impact on the secondary electron emission yield of a growing graphite layer deposited on copper substrates is analyzed. The numerical simulations confirm experimental observations showing that a very thin coating deposit, with a thickness of few nm, can affect significantly the emission yield of an irradiated material. Beyond 5 nm thickness, the surface material alone drives the secondary emission.

The Norgett-Robinson-Torrens displacements per atom function is commonly used to estimate the amount of atomic displacement produced by incident energetic particles. At low incident energy, this function is defined as a step function presenting a single threshold displacement damage energy. But materials have different threshold as a function of the crystallographic orientation. Molecular dynamic simulations show that a continuously varying damage energy probability is best suited to represent the threshold damage region. This work proposes a method to introduce in the NRT damage function a continuous damage energy distribution. The impact of a change on the damage function in the threshold region is evaluated on the incident electrons' Non Ionizing energy Loss.

An analytical formula for the ionizing dose of low energy electrons is proposed. The expressions have been validated for 11 monatomic elements (C, Be, Al, Si, Ti, Ni, Cu, Ge, Ag, Fe and W) and for energies ranging from 10 eV up to 14.5 keV by the use of low energy Monte Carlo simulations. These expressions can be used to evaluate the energy loss of low energy electrons as an input for other simulation codes.

The increase in temperature leads to an increase of the vibrations of the material's lattice and thus to a greater probability of electron-phonon interaction. Therefore, in principle, it is expected that the increase in the temperature leads to decrease of the electron emission yield (TEY). However, in metals, the most main energy loss processes is the electron-electron interaction. Therefore, it is anticipated that the TEY of metals is expected to be significantly insensitive between -150°C to and 200°C. Despite this well-established assertion, the effect of the temperature on the TEY is still being intensively discussed in the multipactor community.

A Monte-Carlo code has been developed for the transport of low energy electrons and the simulation of the internal charge buildup induced by the electron irradiation in thin films of amorphous SiO2. The code is validated with time resolved experimental Electron Emission Yield (EEY) data on 20 nm SiO2 thin films for incident electrons of 300 eV and 1 keV. As the EEY is greater than 1, this corresponds to the case of positive charging. In order to assess the impact of the charge buildup on the electron emission yield, the samples have been negatively polarized to suppress the positive external charging effects, and irradiated with a defocused beam (mm2). A direct correlation is found between the value of the EEY and the density of holes created in the material. This clearly shows that the recombination of the secondary electrons with trapped holes significantly affects the EEY of insulators.

A review of linear (dielectric theory) and nonlinear (binary collision theory) formalisms is proposed. The range of validity of both theories is discussed. The differential energy cross sections are fully detailed so that they are suitable for use in any Monte Carlo code. The use of the nonlinear formalism (and consequently the description of the differential cross sections) in a Monte Carlo code, such as GEANT4, is poorly addressed in the literature. In order to cover a very wide energy range, a combined model is discussed and implemented in GEANT4. Applications related to the space domain are studied, and the benefit of our combined model is investigated through a dedicated code devoted to the estimation of deposited energy in nanometric volumes.

Non Ionizing Energy Loss (NIEL) is the metric conventionally used to scale displacement damage degradation of irradiated semiconductor materials. Degradation of many electrical parameters is scaled according to this average parameter. But some deviations from NIEL scaling approach are observed from time to time. The stochastic nature of irradiation is often ignored. But, the degradation is not necessarily proportional to the average degradation level given by NIEL. The scatter of the irradiation degradation level is studied in this paper. This analysis provides some hints in order to interpret some discrepancies observed between measurements and predictions made with NIEL. Reliability of NIEL scaling method, applied to dark current degradation, is discussed for Silicon and Gallium Arsenide optoelectronic devices.

The Secondary Electron Emission (SEE) process plays an important role in the performance of various devices. For instance, the multipactor mechanism, driven by SEE, affects radio-frequency components of space missions. SEE is also a concern in other domains, for instance the accelerator physics community, where the beam lines stability can strongly be affected by the initiation of electron clouds. Electron extrapolated range, which is a measure of the penetration distance of electrons in solids is a fundamental parameter required to understand and model this SEE mechanism. Our goal, by means of simulations, is to provide a better knowledge of the range of electrons at low energy (<~10 keV), the domain of energy where the risk of triggering an electron cloud is maximum. We have developed a Monte Carlo electron transport code for low energy electrons [~eV, ~10 keV]. It has been used to study the practical range of electrons in the energy domain of interest for the SEE machanism. This work proposes to formulate, below ~10 keV, an analytic range vs. energy expression.