In the present work, we report the 25 MeV oxygen irradiation effects in n -type single crystal β -Ga ₂ O ₃ at different fluences. We demonstrate that the symmetric stretching modes and bending vibrations of GaO ₄ and GaO ₆ units are impaired upon increasing O irradiation fluence. Blue and green photoluminescence (PL) emission bands are found to be mainly associated with gallium–oxygen divacancies, gallium vacancies and oxygen interstitials. The increase of optically active centers at low fluence and the PL quenching at high fluence are ascribed to the reduction of carrier density and the production of non-radiative recombination centers, respectively. The results envisage the possibility of obtaining pre-designed spectral behaviors by varying the oxygen irradiation fluence.

Characteristics of displacement defects in n-p-n bipolar junction transistors (BJTs) caused by heavy ions with various nonionizing energy loss (NIEL) values are studied in this paper. The key electrical parameters are measured in situ during irradiation. Behavior of the radiation-induced defects is characterized by deep level transient spectroscopy (DLTS) after the irradiation and the post irradiation annealing. Experimental results indicate that at a given displacement damage dose, the excess base current shows two ideality factors, which are close to 2 for small VEB and close to 1 for large VEB, respectively. Moreover, the two ideality factors do not change with the increasing irradiation fluence. These results indicate that heavy ion irradiations mainly produce displacement damage on the BJTs. With increasing displacement damage dose, the change in the reciprocal of current gain caused by 10-40 MeV Si and 25 MeV O ions can be normalized in one line, which shows the displacement damage is independent of the NIEL value. Based on the DLTS analysis and isochronal annealing, at a given displacement damage dose, the characteristic of displacement defects caused by 40 MeV Si, 10 MeV Si, and 25 MeV O ion irradiations is different. Heavy ions with low NIEL value primarily generate isolated defects in the BJTs, while heavy ions with high NIEL value mainly produce clustered defects. Therefore, we conclude that although the displacement defects caused by heavy ions with various NIEL are different, the degradation of the electrical property of the BJTs is independent of NIEL.

Calculations using the Heyd–Scuseria–Ernzerhof screened hybrid functional reveal the detailed influence that surface vacancies have on the electronic and optical properties of low-dimensional (LD) β-Ga₂O₃.

Spin–orbit torque magnetic tunnel junction (SOT-MTJ) is the memory cell of magnetic random access memory (MRAM), which is a promising candidate for upper level cache in the harsh environment due to nonvolatility, high speed, and high endurance. Therefore, it is significant to research the mechanism of irradiation effects on the SOT-MTJ before its integration onboard. This article investigates the ionization and displacement damage of in-plane magnetic anisotropy SOT-MTJ, including 1-MeV electron and 17.2-keV He ⁺ and ⁶⁰ Co gamma irradiations with various fluences and doses, respectively. The devices are resilient to tunnel magnetoresistance (TMR), whereas the magnetic properties are changed after irradiation. The 100-Mrad (Si) gamma and 17.2-keV He ⁺ irradiations generate similar damages on the device performances, in the aspects of the magnetic anisotropy and critical current density ( $J_{\mathrm {c}}$ ). However, the displacement damage originating from the electron irradiation does not have a significant influence on $J_{\mathrm {c}}$ . In addition, the saturation magnetization and exchange bias field are changed by irradiations without regularity. Some possible mechanisms are discussed to explain the experimental results through the simulation of stopping and range of ions in matter (SRIM) and microstructural tests.

The effects of space radiation on the structural and electrical properties of MoS ₂ field effect transistors (FETs) were investigated. The 1 MeV electronically equivalent International Space Station (ISS) track was used to apply fluence equivalent to the orbital for 10 (1.0 × 10 ¹² cm ⁻² ) and 30 years (3.0 × 10 ¹² cm ⁻² ) using the AP8 and AE8 models. X-ray photoelectron spectroscopy (XPS), Raman and photoluminescence (PL) spectra were recorded before and after irradiation. Electron irradiation produced strong desulfurization effects in MoS ₂ FETs. The PL spectra before and after irradiation did not change significantly, while the E 2 g 1 and A _1g Raman modes were red- and blue-shifted, respectively. The XPS results demonstrated a strong desulfurization effect of the electron beam on MoS ₂ . This reduction indicates a much higher amount of irradiation-induced S vacancies compared to Mo vacancies. The electrical characteristics of the device were measured before and after irradiation. The increase in the channel leakage current after irradiation was attributed to the oxide trapping positive charges. MoS ₂ FETs irradiated by the electron-beam demonstrated a decreased current. This phenomenon can be attributed to the combination of the states at the SiO ₂ /MoS ₂ interfaces and Coulomb scattering. Our study provides a deeper understanding of the influence of 1 MeV electron-beam irradiation on MoS ₂ -based nano-electronic devices for future space applications.

The influence of surface carrier concentration on the ideality factor of excess base current ( $\varDelta$ IB) in gated lateral PNP (GLPNP) bipolar junction transistors (BJTs) induced by 1 MeV electrons is investigated. $\varDelta$ IB in LPNP BJTs is impacted by the surface carrier density and radiation-induced interface traps. In GLPNP BJTs, the surface carrier concentration can be controlled by the voltage applied to a gate over the base region. The ideality factor changes after irradiation, and its dependence on emitter- base voltage (V $_{EB}$ ) is a function of gate voltage. For the irradiated devices, as the gate voltage decreases from +20 V to -5 V, the ideality factor for excess base current changes from a single slope to two-slope behavior. The majority carrier concentration at the surface of the base, controlled by the gate voltage, impacts the excess base current and its ideality factor.