Impact Of Electron Irradiation Research Articles

Impact of electron irradiation on semi-insulating and conductive β-Ga2O3 single crystals.

The damage behavior and defect evolution in Si-doped and Fe-doped β-Ga2O3 crystals were investigated using an electron irradiation of 1 MeV at a dose of 1 × 1016 cm-2 in conjunction with structural and optoelectronic characterizations. Distinct decline in electron spin resonance (ESR) signal with g = 1.96 and a UV luminesce of 375 nm were observed in Si-doped β-Ga2O3 due to the capture of free carriers by irradiation defects. As for the Fe-doped sample, both defect-related blue emission and Cr3+ impurity-related red luminescence underwent prominent suppression after electron irradiation, which can be correlated to the creation of VO and VGa defects and the formation of non-radiative recombination. Noticeably, neither VO- nor VGa-related ESR signals were detected in Fe-doped and Si-doped β-Ga2O3 irrespective of irradiation; g = 2.003 resonance was observed in Mg-doped β-Ga2O3 and it experienced remarkable augmentation after electron irradiation. We assigned the g = 2.003 peak to the VGa acceptor. Besides, although the Raman mode of 258 cm-1 in Si-doped β-Ga2O3 has been suggested to be electron concentration dependent, no obvious change in peak intensity was observed before and after electron irradiation.

Creation of NV Centers in Diamond under 155 MeV Electron Irradiation

AbstractSingle‐crystal diamond substrates presenting a high concentration of negatively charged nitrogen‐vacancy centers (NV−) are on high demand for the development of optically pumped solid‐state sensors such as magnetometers, thermometers, or electrometers. While nitrogen impurities can be easily incorporated during crystal growth, the creation of vacancies requires further treatment. Electron irradiation and annealing is often chosen in this context, offering advantages with respect to irradiation by heavier particles that negatively affect the crystal lattice structure and consequently the NV− optical and spin properties. A thorough investigation of electron irradiation possibilities is needed to optimize the process and improve the sensitivity of NV‐based sensors. In this work, the effect of electron irradiation is examined in a previously unexplored regime: extremely high energy electrons, at 155 MeV. A simulation model is developed to estimate the concentration of created vacancies and an increase of NV− concentration by more than three orders of magnitude following irradiation of a nitrogen‐rich HPHT diamond over a very large sample volume is experimentally demonstrated, which translates into an important gain in sensitivity. Moreover, the impact of electron irradiation in this peculiar regime on other figures of merits relevant for NV sensing is discussed, including charge state conversion efficiency and spin relaxation time. Finally, the effect of extremely high energy irradiation is compared with the more conventional low energy irradiation process, employing 200 keV electrons from a transmission electron microscope, for different substrates and irradiation fluences, evidencing 60‐fold higher yield of vacancy creation per electron at 155 MeV.

Electrons irradiation of III-V//Si solar cells for NIRT conditions

— In this study, we evaluate the potential of III-V//Si solar cell technology for space applications. We present experimental results on wafer bonded 2-terminal III-V//Si solar cells degradation under 1 MeV electrons irradiation. Beginning-Of-Life (BOL) and End Of Life (EOL) electrical performances were measured under Normal Irradiance (100% AM0) and Room Temperature (300K) conditions (NIRT). No degradation of the wafer bonding interface was detected. The impact of electron irradiation on effective diffusion length in the silicon bottom cell was calculated using the Internal Quantum Efficiency model for different solar cells architectures. Improvement paths towards higher EOL III-V//Si solar cells are discussed.

Changes in structure of PA6 during electron irradiation

The impact of electron irradiation on the structure of the PA6 polymer is researched in this article. The electron beam irradiation of samples from PA6 was carried out on an industrial pulse accelerator ILU-10 under different modes. Beam energy and radiation dose varied. The structural changes of PA6 were studied by scanning electron microscopy, X-ray phase analysis, IR Fourier spectroscopy, and the thermal characteristics of the polymer were studied by differential scanning calorimetry. It was revealed that after electron beam treatment, the melting temperature of the PA6 polymer decreases from 214 °C to 217 °C. It was found that electron beam treatment leads to a change in the surface morphology, that is, the surface becomes rough, the depth of the roughness and the structure of spherulites increase.

Impact of Electron Irradiation on Transition Temperature of Pb-Substituted Bi-2223 Superconductor

The synthesis of (Bi1-xPbx)2Sr2Ca2Cu3O8+σ (x=0 and 0.4) bulk samples (hereafter called as Bi-2223) were completed by using solid-state reaction method. The Bi-2223 samples were subjected to calcination for 24 hours at 840°C, Then, the pelletized powder for both samples were sintered at 865°C for 48 hours. Each sample was exposed to high energy electron irradiation with a dosage of 100 kGray. Structural examination was conducted by using the Bruker D8-Advanced X-ray powder Diffraction (XRD). According to Bi-2223 indexed phase structure, the XRD patterns obtained shows that the samples, both Bi-2223 (x=0 and x=0.4) samples showed well-defined peaks and phase structure remains unchanged after the sample being exposed to the electron source. Measurement of the critical temperature, TC were obtained by using AC susceptibility technique and four-point probe. Bi/Pb (x=0.4) sample showed significant TC value compared to Bi/Pb (x=0) sample. Grain alignment in SEM micrographs show enhancement in their grain connectivity and also layering texture in irradiated sample which might lead to has better superconducting properties. In contrast, the impact of electron irradiation on its microstructure and consequently the TC was destructive in the Bi/Pb (x=0) sample.

Impact of Electron Irradiation on the ON-State Characteristics of a 4H–SiC JBS Diode

The ON-state characteristics of a 1.7-kV 4H–SiC junction barrier Schottky diode were studied after 4.5-MeV electron irradiation. Irradiation doses were chosen to cause a light, strong, and full doping compensation of an epitaxial layer. The diodes were characterized using Deep Level Transient Spectroscopy, $C$ – $V$ (T), and $I$ – $V$ measurements without postirradiation annealing. The calibration of model parameters of a device simulator, which reflects the unique defect structure caused by the electron irradiation, was verified up to 2000 kGy. The quantitative agreement between simulation and measurement requires: 1) the Shockley–Read–Hall model with at least two deep levels on the contrary to ion irradiation and 2) a new model for enhanced mobility degradation due to radiation defects. The diode performance at high electron fluences is shown to be limited by the doping compensation at the epitaxial layer.

High-power silicon P–i–N diode with cathode shorts: The impact of electron irradiation

Large-area silicon P–i–N diodes (VRRM=4.5kV, IFAV≈3kA, Aactive≈55cm2) were processed with cathode shorts in order to conserve the softness under reverse recovery, while employing a 10% thinner silicon wafer for a better technology curve for the static and dynamic losses. Contrarily to existing designs, the cathode shorts have approximately one order of magnitude higher surface concentration of the P+ layer than the N+ emitter. Except for the implanted N-type buffer, these shorts were processed using the dopant deposition from POCl3 and H3BO3. The diodes with and without cathode shorts have been compared for the static parameters. The dynamic behavior has been also compared at reverse recovery of a free-wheeling diode in a standard IGCT circuit. The impact of electron irradiation on the softness of the reverse recovery has been evaluated up to 125°C.

Modification of porous ultra-low K dielectric by electron-beam curing

The impact of electron irradiation on ultra-low K (ULK) porous dielectric material used in advanced interconnects is analyzed using spectroscopic and electrical characterizations. The e-beam irradiation modifies the chemical composition, the porosity and the optical indexes. The effects of e-beam curing on electrical properties and dielectric reliability are also evaluated.

Impact of electron irradiation on particle track etching response in polyallyl diglycol carbonate (PADC)

In the present work, attempts have been made to investigate the modification in particle track etching response of polyallyl diglycol carbonate (PADC) due to impact of 2 MeV electrons. PADC samples pre-irradiated to 1, 10, 20, 40, 60, 80 and 100 Mrad doses of 2 MeV electrons were further exposed to 140 MeV28 Si beam and dose-dependent track registration properties of PADC have been studied. Etch-rate values of the PADC irradiated to 100 Mrad dose electron was found to increase by nearly 4 times that of pristine PADC. The electron irradiation has promoted chain scissioning in PADC, thereby converting the polymer into an easily etchable polymer. Moreover, the etching response and the detection efficiency were found to improve by electron irradiation. Scanning electron microscopy of etched samples further revealed the surface damage in these irradiated PADCs.