Semi-insulating GaAs detectors degraded by 8 MeV electrons up to 1500 kGy

2021 ◽  
Vol 16 (12) ◽  
pp. C12032
Author(s):  
A. Sagatova ◽  
V. Krsjak ◽  
S. Sojak ◽  
O. Riabukhin ◽  
E. Kovacova ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Collection Efficiency ◽  
Bulk Material ◽  
Substrate Material ◽  
Charge Collection Efficiency ◽  
Positron Annihilation Lifetime ◽  
Current Voltage ◽  
Radiation Degradation ◽  
Applied Dose ◽  
Radiation Induced

Abstract Radiation degradation of semi-insulating GaAs detectors by 8 MeV electrons up to doses of 1500 kGy is studied in this paper. The influence of irradiation on GaAs material parameters and on spectrometric and electrical properties of fabricated detectors is evaluated. The detector material was degraded before contact preparation, which ensured separation of radiation degradation solely to the bulk material, excluding the contact degradation. The positron annihilation lifetime spectroscopy (PALS) was involved to characterize the substrate material together with galvanometric measurements. Radiation-induced mono-vacancies were clearly identified by PALS in the irradiated materials with increasing concentration up to 2.8 × 1016 cm−3 at maximal applied dose. In correlation with defect concentration the electron Hall mobility decreased with dose down to 3270 cm2 V−1 s−1 and resistivity increased up to 5.22 × 108 Ω cm at 1500 kGy. The bulk material properties influenced the parameters of fabricated detectors. The detectors lost their current blocking behaviour at 1000 kGy according to current-voltage measurements. The charge collection efficiency during alpha-particle and gamma ray measurements almost exponentially decreased with applied dose from initial 40% down to 5% at 1500 kGy in the case of alpha spectrometry and from 48% to 12% at 500 kGy for gamma spectrometry.

The Influence of the Extreme Fluences of 8 MeV Protons on Characteristics of SiC Nuclear Detectors Produced by Al Implantation

2007 ◽  
Vol 556-557 ◽  
pp. 961-964 ◽  
Author(s):  
Alexander M. Ivanov ◽  
Nikita B. Strokan ◽  
Alexander A. Lebedev ◽  
Vitalii V. Kozlovski
Keyword(s):  
Experimental Data ◽  
Collection Efficiency ◽  
Charge Collection ◽  
Carrier Localization ◽  
Charge Collection Efficiency ◽  
Radiation Induced ◽  
Nuclear Detectors ◽  
Two Parameter ◽  
Mev Protons ◽  
Α Particles

The charge collection efficiency (ССЕ) of SiC-detectors preliminarily irradiated with 8 MeV protons at a fluence of 1014 cm-2 has been studied. Nuclear spectrometric techniques with 5.4 MeV α-particles were employed to test the detectors. The concentration of primarily created defects was estimated to be 4×1016 cm-3. A strong compensation of SiC was observed, which allowed connection of the structure in the forward mode. The experimental data obtained were processed using a simple two-parameter model of signal formation. The model makes it possible to separate the contributions of electrons and holes to the ССЕ. An additional irradiation at a fluence of 2×1014 cm-2 reduced the ССЕ value by a factor of 2 and gave rise to polarization. The latter indicates that radiation-induced centers are not only actively involved in carrier localization (with a decrease in the lifetime), but also in transformation of the electric field within the detector.

scholarly journals Effect of Deoxycholic Acid on the Performance of Liquid Electrolyte Dye-Sensitized Solar Cells Using a Perylene Monoimide Derivative

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Ganesh D. Sharma ◽  
Rajnish Kurchania ◽  
Richard J. Ball ◽  
Mahesh S. Roy ◽  
John A. Mikroyannidis
Keyword(s):  
Deoxycholic Acid ◽  
Collection Efficiency ◽  
Short Circuit ◽  
Liquid Electrolyte ◽  
Open Circuit ◽  
Charge Collection Efficiency ◽  
Dye Sensitized ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Open Circuit Photovoltage

The effect of coadsorption with deoxycholic acid (DCA) on the performance of dye-sensitized solar cell based on perylene monoimide derivative (PCA) as sensitizer and liquid electrolyte had been investigated. The current-voltage characteristics under illumination and incident photon to current efficiency (IPCE) spectra of the DSSCs showed that the coadsorption of DCA with the PCA dye results in a significant improvement in short circuit photocurrent and slight increase in the open circuit photovoltage, which lead to an overall power conversion efficiency. The enhancement of short circuit current was attributed to the increased electron injection efficiency from the excited state of PCA into the conduction band of TiO2and charge collection efficiency. The current-voltage characteristics in dark indicates a positive shift in the conduction which also supports the enhancement in the photocurrent. The coadsorption with DCA suppressed charge recombination as indicated from the electrochemical impedance spectra and thus improved the open circuit photovoltage.

Operation of Al-Implanted SiC Nuclear Detectors Subjected to High Radiation Fluences at Temperatures of up to 250 °C

2009 ◽  
Vol 615-617 ◽  
pp. 853-856
Author(s):  
Alexander M. Ivanov ◽  
Nikita B. Strokan ◽  
Alexander A. Lebedev ◽  
Vitalii V. Kozlovski
Keyword(s):  
Collection Efficiency ◽  
Amplitude Spectrum ◽  
Radiation Detectors ◽  
Nuclear Radiation ◽  
Charge Collection Efficiency ◽  
Radiation Induced ◽  
Two Stages ◽  
Nuclear Detectors ◽  
Nuclear Radiation Detectors ◽  
Induced Defects

The effect of a cycle "introduction of defects – annealing – introduction of defects" on the SiC properties has been studied to know the degradation of characteristics of p-n- nuclear radiation detectors. The irradiation with 8 МeV protons at fluences of about 3×1014 сm-2 was used. The annealing was carried out in two stages one-hour at temperatures of 600 and 700 °С. Nuclear spectrometric techniques with 5.8 MeV -particles were employed to test the detectors. The charge collection efficiency and features of the amplitude spectrum were determined to study the capture of charge carriers by radiation-induced defects. Measurements were made in the temperature range of 20–250 °С. It is shown that at 250 °С there is a decrease in the carriers capture. The form of the amplitude spectrum essentially improves. The first irradiation and the subsequent annealing do not change significantly the radiation hardness of SiC. During the second irradiation the effective concentration of the introduced centers is 1.3 times higher. This result may be due to the high total fluence of protons, 6×1014 cm-2.

Mitigation of Radiation-induced Gastrointestinal System Injury using Resveratrol or Alpha-lipoic Acid: A Pilot Histopathological Study

2020 ◽  
Vol 19 (4) ◽  
pp. 413-424
Author(s):  
Bagher Farhood ◽  
Gholamreza Hassanzadeh ◽  
Peyman Amini ◽  
Dheyauldeen Shabeeb ◽  
Ahmed Eleojo Musa ◽  
...  
Keyword(s):  
Lipoic Acid ◽  
Gamma Ray ◽  
Morphological Changes ◽  
Gastrointestinal System ◽  
Alpha Tocopherol ◽  
Whole Body ◽  
Histopathological Study ◽  
Alpha Lipoic Acid ◽  
Pilot Investigation ◽  
Radiation Induced

Aim: In this study, we aimed to determine possible mitigation of radiationinduced toxicities in the duodenum, jejunum and colon using post-exposure treatment with resveratrol and alpha-lipoic acid. Background: After the bone marrow, gastrointestinal system toxicity is the second critical cause of death following whole-body exposure to radiation. Its side effects reduce the quality of life of patients who have undergone radiotherapy. Resveratrol has an antioxidant effect and stimulates DNA damage responses (DDRs). Alpha-lipoic acid neutralizes free radicals via the recycling of ascorbic acid and alpha-tocopherol. Objective: This study is a pilot investigation of the mitigation of enteritis using resveratrol and alpha-lipoic acid following histopathological study. Methods: 60 male mice were randomly assigned to six groups; control, resveratrol treatment, alpha-lipoic acid treatment, whole-body irradiation, irradiation plus resveratrol, and irradiation plus alpha-lipoic acid. The mice were irradiated with a single dose of 7 Gy from a cobalt-60 gamma-ray source. Treatment with resveratrol or alpha-lipoic acid started 24 h after irradiation and continued for 4 weeks. All mice were sacrificed after 30 days for histopathological evaluation of radiation-induced toxicities in the duodenum, jejunum and colon. Results and Conclusion: Exposure to radiation caused mild to severe damages to vessels, goblet cells and villous. It also led to significant infiltration of macrophages and leukocytes, especially in the colon. Both resveratrol and alpha-lipoic acid were able to mitigate morphological changes. However, they could not mitigate vascular injury. Conclusion: Resveratrol and alpha-lipoic acid could mitigate radiation-induced injuries in the small and large intestine. A comparison between these agents showed that resveratrol may be a more effective mitigator compared to alpha-lipoic acid.

scholarly journals Influence of Substrate Materials on Nucleation and Properties of Iridium Thin Films Grown by ALD

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 173
Author(s):  
Paul Schmitt ◽  
Vivek Beladiya ◽  
Nadja Felde ◽  
Pallabi Paul ◽  
Felix Otto ◽  
...  
Keyword(s):  
Thin Films ◽  
Film Growth ◽  
Bulk Material ◽  
Atomic Layer ◽  
Substrate Material ◽  
Fused Silica ◽  
Silicon Wafers ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Influence Of Substrate

Ultra-thin metallic films are widely applied in optics and microelectronics. However, their properties differ significantly from the bulk material and depend on the substrate material. The nucleation, film growth, and layer properties of atomic layer deposited (ALD) iridium thin films are evaluated on silicon wafers, BK7, fused silica, SiO2, TiO2, Ta2O5, Al2O3, HfO2, Ru, Cr, Mo, and graphite to understand the influence of various substrate materials. This comprehensive study was carried out using scanning electron and atomic force microscopy, X-ray reflectivity and diffraction, four-point probe resistivity and contact angle measurements, tape tests, and Auger electron spectroscopy. Within few ALD cycles, iridium islands occur on all substrates. Nevertheless, their size, shape, and distribution depend on the substrate. Ultra-thin (almost) closed Ir layers grow on a Ta2O5 seed layer after 100 cycles corresponding to about 5 nm film thickness. In contrast, the growth on Al2O3 and HfO2 is strongly inhibited. The iridium growth on silicon wafers is overall linear. On BK7, fused silica, SiO2, TiO2, Ta2O5, Ru, Cr, and graphite, three different growth regimes are distinguishable. The surface free energy of the substrates correlates with their iridium nucleation delay. Our work, therefore, demonstrates that substrates can significantly tailor the properties of ultra-thin films.

3D imaging of radiation damage in silicon sensor and spatial mapping of charge collection efficiency

2013 ◽  
Vol 8 (03) ◽  
pp. C03023-C03023 ◽  
Author(s):  
M Jakubek ◽  
J Jakubek ◽  
J Zemlicka ◽  
M Platkevic ◽  
V Havranek ◽  
...  
Keyword(s):  
Radiation Damage ◽  
3D Imaging ◽  
Collection Efficiency ◽  
Charge Collection ◽  
Spatial Mapping ◽  
Charge Collection Efficiency ◽  
Silicon Sensor

Gamma-Ray Radiation-Induced Surface Hydrophobic Effects in Invar Alloy

2012 ◽  
Vol 482-484 ◽  
pp. 1585-1591 ◽  
Author(s):  
Cheng Fu Yang ◽  
Wei Wen Wang ◽  
Hsin Hwa Chen ◽  
Wei Tan Sun ◽  
Chi Lin Shiau ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Structural Changes ◽  
Gamma Ray ◽  
Small Deviation ◽  
Contact Angles ◽  
Invar Alloy ◽  
Hydrophobic Effects ◽  
Post Irradiation ◽  
Radiation Induced ◽  
Gamma Ray Irradiation

In this paper, we report a new phenomenon observed in the gamma-ray radiation-induced hydrophobic effects on an Invar surface: When the Invar alloy is subjected to different doses of gamma-ray irradiation, the contact angle increases with the radiation dose. Invar samples with exposed to a higher dose appear more hydrophobic, but this tendency disappears following post-irradiation etching. The contact angles of the irradiated and etched Invar samples can be restored back to a stable value with small deviation after 30 min of annealing at 150°C. X-ray diffraction (XRD) analysis found no crystalline structural changes. High resolution field emission scanning microscope (FE-SEM) analyses showed that irradiation might induce crack-like surfaces which could be removed at higher radiation dose in the following acid etchings. It is believed that the chemical bonds of Invar oxide on the surface were broken by the gamma-ray irradiation, thus raising the likelihood of binding with free ions in the air and resulting in the exclusion of the hydrophilic OH bonds, leaving a hydrophobic post-irradiation Invar surface.

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