High-energy proton irradiation effects on GaInP/GaAs/Ge triple junction cells

The effect of high-energy proton irradiation on the physical properties of carbon nanotubes(CNTs) was investigated. The focus of the study was on the electrical properties ofsingle-walled carbon nanotube (SWNT) network devices exposed to proton beams.Field-effect transistors (FETs) of network type were fabricated using SWNTs andwere then irradiated by high-energy proton beams of 10–35 MeV with a fluence of4 × 1010–4 × 1012 cm−2 that are comparable to the aerospace radiation environment. The electrical properties ofboth metallic and semiconducting CNT network FET devices underwent no significantchange after the high-energy proton irradiation, indicating that the CNT network devicesare very tolerant in proton beams. Raman spectra confirm the proton-radiation hardness ofCNT network FET devices. The radiation hardness of CNT network FET devices promisestherefore the potential usefulness of CNT-based electronics for future space application.

The effect of high-energy proton irradiation on GaN-based ultraviolet avalanche photodiodes (APDs) is investigated. The dark current of the GaN APD is calculated as a function of the proton energy and proton fluences. By considering the diffusion, generation–recombination, local hopping conductivity, band-to-band tunneling, and trap-assisted tunneling currents, we found that the dark current increases as the proton fluence increases, but decreases with increasing proton energy.

Proton irradiation effects in CuInSe2 (CIS) thin films have been investigated as a function of proton energy (0.38, 1 and 3 MeV). Single crystalline n-CIS thin films were prepared by radio frequency sputtering. The electrical properties of as-grown and irradiated samples were measured. The typical electron concentration and Hall mobility in as-grown samples were 4 × 1016 cm−3 and 120 cm2/Vs, respectively. After 0.38 and 1MeV proton irradiation, both of the electron concentration and Hall mobility were decreased as the fluence exceeded 1 × 1013 cm−2, but for 3 MeV proton irradiation, they were decreased over the fluence of 1 × 1014 cm−2. The damage by high-energy proton irradiation was lower than that by low-energy proton irradiation. The carrier removal rate with proton fluence was estimated about from 1800 to 300 cm−1 as proton energy was changed from 0.38 to 3 MeV. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

There are no data available about the physiological response of mammals to total-body proton irradiation. Previous studies (1) have dealt with either the effects of focal irradiation or mortality after total-body irradiation. The present study was undertaken to compare the effects of total-body 'y-irradiation and proton irradiation on the cardiovascular system of the rhesus monkey. The effects of proton irradiation on blood pressure, heart rate, electrocardiogram, cardiac output, and the response to norepinephrine were studied at energies of 32, 55, 138, and 400 Mev. A single dose of about 3900 rads to the surface was used, since previous studies with y-rays (2) showed that this dose produced a pronounced fall in blood pressure, without signs of focal neurological damage and in the absence of significant fluid and electrolyte imbalance. Although differences in depth-dose distribution, particularly at low energies, preclude the calculation of a meaningful relative biological effectiveness (RBE) (3, 4), the data from the proton-irradiated animal are compared to data from y-irradiated animals. This comparison shows a similarity between the effect of total-body y-irradiation and proton irradiation at high proton energies and a dependence of the effects on depth-dose distribution at low proton energies.

In this paper we explore the effects of 3.5 MeV proton irradiation on Fe(Se,Te) thin films grown on CaF2. In particular, we carry out an experimental investigation with different irradiation fluences up to 7.30 · 1016 cm−2 and different proton implantation depths, in order to clarify whether and to what extent the critical current is enhanced or suppressed, what are the effects of irradiation on the critical temperature, resistivity, and critical magnetic fields, and finally what is the role played by the substrate in this context. We find that the effect of irradiation on superconducting properties is generally small compared to the case of other iron-based superconductors. The irradiation effect is more evident on the critical current density Jc, while it is minor on the transition temperature Tc, normal state resistivity ρ, and on the upper critical field Hc2 up to the highest fluences explored in this work. In more detail, our analysis shows that when protons implant in the substrate far from the superconducting film, the critical current can be enhanced up to 50% of the pristine value at 7 T and 12 K; meanwhile, there is no appreciable effect on critical temperature and critical fields together with a slight decrease in resistivity. On the contrary, when the implantation layer is closer to the film–substrate interface, both critical current and temperature show a decrease accompanied by an enhancement of the resistivity and lattice strain. This result evidences that possible modifications induced by irradiation in the substrate may affect the superconducting properties of the film via lattice strain. The robustness of the Fe(Se,Te) system to irradiation-induced damage makes it a promising compound for the fabrication of magnets in high-energy accelerators.

β-Ga2O3 based solar-blind photodetectors have strong radiation hardness and great potential applications in Earth's space environment due to the large bandgap and high bond energy. In this work, we investigated the photoelectric properties influence of β-Ga2O3 photodetector irradiated by 100 MeV high-energy protons which are the primary components in the inner belt of the Van Allen radiation belts where solar-blind photodetectors mainly worked. After proton irradiation, due to the formation of more oxygen vacancies and their migration driven by bias at the metal/semiconductor interface, transportation of carriers transforms with electron tunneling conduction for low-resistance state and thermionic emission for high resistance state. As a result, the current–voltage curves of β-Ga2O3 solar-blind photodetectors exhibit apparent hysteresis loops. The photoresponsivity of β-Ga2O3 photodetectors slightly increases from 1.2 × 103 to 1.4 × 103 A/W after irradiation, and the photoresponse speed becomes faster at a negative voltage while slower at positive voltage. The results reveal the effects of high-energy proton irradiation on β-Ga2O3 solar-blind photodetectors and provide a basis for the study of their use in a radiation harsh environment.

In this article, the effects of high-energy proton irradiation on top-gate graphene field-effect transistors (GFETs) were investigated by using 20 MeV protons. The basic electrical parameters of the top-gate GFETs were measured before and after proton irradiation with a fluence of 1 × 1011 p/cm2 and 5 × 1011 p/cm2, respectively. Decreased saturation current, increased Dirac sheet resistance, and negative drift in the Dirac voltage in response to proton irradiation were observed. According to the transfer characteristic curves, it was found that the carrier mobility was reduced after proton irradiation. The analysis suggests that proton irradiation generates a large net positive charge in the gate oxide layer, which induces a negative drift in the Dirac voltage. Introducing defects and increased impurities at the gate oxide/graphene interface after proton irradiation resulted in enhanced Coulomb scattering and reduced mobility of the carriers, which in turn affects the Dirac sheet resistance and saturation current. After annealing at room temperature, the electrical characteristics of the devices were partially restored. The results of the technical computer-aided design (TCAD) simulation indicate that the reduction in carrier mobility is the main reason for the degradation of the electrical performance of the device. Monte Carlo simulations were conducted to determine the ionization and nonionization energy losses induced by proton incidence in top-gate GFET devices. The simulation data show that the ionization energy loss is the primary cause of the degradation of the electrical performance.

The effects of high-energy proton irradiation on the electrical characteristics of Au/Ni/4H-SiC Schottky barrier diodes

In this work, the effect of high-energy proton irradiation on the radiofrequency (RF) properties of silicon-on-insulator (SOI) substrates is investigated. The localized backside etching (LBE) structure is introduced for RF properties improvement and proton irradiation hardening. It is observed that after the 50 MeV proton irradiation with a fluence of 1 × 1012 p cm−2, the attenuation, crosstalk, and relative permittivity significantly decrease for conventional SOI substrates. In contrast, LBE substrates are less sensitive to proton irradiation and simultaneously exhibit better RF performance. The enhancement of the LBE structure on irradiation tolerance is qualitatively characterized by the equivalent circuit model parameter extraction.

Transparent conductive oxides are essential materials for many optoelectronic applications. For new devices for aerospace and space applications, it is crucial to know how they respond to the space environment. The most important issue in commonly used low-Earth orbits is proton radiation. This study examines the effects of high-energy proton irradiation (226.5 MeV) on thin films of aluminium-doped zinc oxide (AZO) and indium tin oxide (ITO). We use X-ray diffraction and electron microscopy observations to see the changes in the structure and microstructure of the films. The optical properties and homogeneity of the materials are determined by spectrophotometry and spectroscopic ellipsometry (SE). Analysis of the chemical states of the elements with X-ray photoelectron spectroscopy (XPS) gives insight into what proton irradiation changes at the surface of the oxides. All measurements show that ITO is less influenced than AZO. The proton energy and fluence used in this study simulate about a hundred years in low Earth orbit. This research demonstrates that both transparent conductive oxide thin films can function under simulated space conditions, with ITO showing superior resilience. The ITO film was more homogenous in terms of the total thickness measured with SE, had fewer defects and adsorbates present on the surface, as XPS analysis proved, and did not show a difference after irradiation regarding its optical properties, transmission, refractive index, or extinction coefficient.

Electric field and space-charge distribution in SI GaAs: effect of high-energy proton irradiation

Effects of 5 MeV proton irradiation on 4H-SiC lateral pMOSFETs on-state characteristics

MeV proton irradiation damage in Ta: Measurements, characterization and comparison to W

We have studied the effects of high-energy proton irradiation on the magnetism of the transition-metal dichalcogenide MoS2. The pristine sample showed ferromagnetic and paramagnetic responses with a diamagnetic background, which all decreased initially with increasing irradiation dose. The ferromagnetic component increased subsequently with further irradiation, for which a spin-3/2 species was identified from the analysis of the M(H) curve, in contrast to the spin-1 species identified in the pristine sample. The magnetism in our MoS2 samples may be accounted for by the structural defects that apparently are cured by low-dose proton irradiation and subsequently become significant by further irradiation.

The effect of high-energy proton irradiation on the microstructure of amorphous Fe–Si–C ribbons