Article
Materials Science, Multidisciplinary
Xiao Cui, Keyu Ji, Taiping Zhang, Bingjun Wang, Wei Sha, Zilong Dong, Yuanhong Shi, Chunsheng Jiang, Qilin Hua, Weiguo Hu
Summary: This paper investigates the influence of low-fluence neutron irradiation on the electrical properties of AlGaN/GaN HEMTs. The results show that the output performance of the irradiated samples changes similarly, with almost no changes or slight decreases near the knee voltage. As for the leakage current, samples irradiated with different fluences exhibit different characteristics. Simulations using Crosslight software further reveal that low-fluence neutron irradiation primarily affects the 2DEG mobility and surface states of the HEMTs.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Materials Science, Multidisciplinary
Xiang Fu, Biao Wei, Jianbin Kang, Wangping Wang, Ge Tang, Qian Li, Feiliang Chen, Mo Li
Summary: This study reports the impact of fast neutron irradiation on the dark current and gain characteristics of Si-based and GaN-based APDs. The dark current of Si-based APDs increases with neutron fluence, while the gain decreases at high fluence. In contrast, the avalanche property of GaN-based APDs is almost unaffected. The optical absorption between the acceptor state and the conduction band in the p-type layer plays a crucial role in influencing the change of dark current and gain at high reverse bias voltage.
RESULTS IN PHYSICS
(2022)
Article
Physics, Applied
Jianping Wang, Fangyuan Shi, Xingzhi Wu, Junyi Yang, Yongqiang Chen, Quanying Wu, Yinglin Song, Yu Fang
Summary: The effect of Fe defects on carrier recombination and two-photon induced ultrafast exciton dynamics in GaN crystals was investigated using femtosecond transient absorption spectroscopy. The absorption kinetics exhibited different characteristics under different nonequilibrium carrier concentrations and distributions. The findings are crucial for the applications of GaN in ultrafast optoelectronics and integrated nonlinear optics.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Xiang Fu, Jianbin Kang, Ge Tang, Feiliang Chen, Qian Li, Mo Li, Biao Wei
Summary: AlGaN-based deep ultraviolet (DUV) light emitting diodes (LEDs) exhibit significant enhancement of output power under neutron irradiation, but performance degradation occurs as neutron fluence increases. The study identifies two competitive mechanisms of neutron radiation effect on DUV LEDs, where increased carrier efficiency in irradiated multi-quantum wells contributes to output power enhancement, while neutron irradiation-induced nitrogen vacancies in the electron blocking layer lead to current leakage and device degradation. These findings not only enrich the degradation mechanism of neutron-irradiated DUV LEDs, but also offer new insights to improve their luminous characteristics.
RESULTS IN PHYSICS
(2021)
Article
Chemistry, Physical
Siti Nurasiah Mat Nawi, Mayeen Uddin Khandaker, S. F. Abdul Sani, S. S. Ismail, K. S. Al-Mugren, Mohammad Amirul Islam, Kamrun Naher, D. A. Bradley
Summary: The study found that both 2B and HB grade PPLGs exhibit excellent linear response within the dose range of 0-200 Gy, with 2B grade PPLGs showing higher sensitivity compared to HB grade PPLGs. The information provided regarding the graphite structures may contribute to the development of cost effective, versatile graphite-based dosimeters.
RADIATION PHYSICS AND CHEMISTRY
(2021)
Article
Materials Science, Multidisciplinary
Gangyuan Jia, Kaiyue Wang, Yufei Zhang, Ruiang Guo, Zunpeng Xiao, Yaqiao Wu, Yuming Tian
Summary: The study creates intrinsic optical defects through electron irradiation and investigates the effects of laser power and measurement temperature using spectroscopy. Different optical centers are associated with different defects. Emissions at 2.091 eV and 2.253 eV are attributed to self-interstitial defects.
Article
Nanoscience & Nanotechnology
Zhiyuan Chen, Yujie Yang, Fang Yao, Yongfu Yang, Yuwei Li, Xuchao Jia, Junqi Dong, Libing Qian, Wanping Chen, Wusheng Zou, Jiangbin Zhao, Jinbiao Pang, Wen Xu, Zhu Wang, Gaokui He, Qianqian Lin
Summary: X-ray detectors based on conventional semiconductors with large atomic numbers have poor stability under high dose rate of ionizing irradiation. However, this study demonstrates that a wide band gap ceramic-boron nitride with small atomic numbers can be used for sensitive X-ray detection. Boron nitride samples showed excellent resistance to ionizing radiation and maintained good charge transport properties even after large dose of neutron irradiation. The fabricated X-ray detectors showed decent performance and the neutron-aged boron nitride showed improved operational stability under continuous X-ray irradiation, suggesting great potential for real applications.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Physical
Alice Hospodkova, Jakub Cizek, Frantisek Hajek, Tomas Hubacek, Jiri Pangrac, Filip Dominec, Karla Kuldova, Jan Batysta, Maciej O. Liedke, Eric Hirschmann, Maik Butterling, Andreas Wagner
Summary: A set of GaN layers prepared by metalorganic vapor phase epitaxy under different technological conditions were investigated using variable energy positron annihilation spectroscopy to find a link between technological conditions, GaN layer properties, and the concentration of gallium vacancies (V-Ga). Different correlations between technological parameters and V-Ga concentration were observed for layers grown from different gallium precursors.
Article
Optics
Baibin Wang, Feng Liang, Degang Zhao, Yuhao Ben, Jing Yang, Ping Chen, Zongshun Liu
Summary: In a studied unintentionally doped GaN sample, the yellow luminescence (YL) band and blue luminescence (BL) band exhibit a transient behavior between 10-300 K, with observed luminescence intensities changing with the exposure time, accompanied by a red-shift of YL peak at 10-140 K and for BL peak at 140 K. These behaviors are proposed to be related to the chemical transformations of YL-related C-N and CNON defects, and BL-related C-N-H-i and CNON-H-i defects during the exposure process.
Article
Optics
E. Feldbach, L. Museur, V. Krasnenko, A. Zerr, M. Kitaura, A. Kanaev
Summary: The formation and evolution of defect levels in the electronic structure of silicon nitride with cubic spinel structure, gamma-Si3N4, after irradiation with He+ ions were investigated using spectroscopic techniques. The changes in cathodoluminescence, photoluminescence, photoluminescence excitation, and Raman spectra were detected. The appearance of a new near-infrared band with close to band gap excitation was attributed to effective trapping of photoinduced electrons and holes by charged defects.
JOURNAL OF LUMINESCENCE
(2021)
Article
Engineering, Electrical & Electronic
Abdulraoof I. A. Ali, Helga T. Danga, Jacqueline M. Nel, Walter E. Meyer
Summary: This study investigated the growth of GaN using electrochemical deposition on different substrates and found that the properties of the film were influenced by both the substrate type and deposition conditions. X-ray diffraction analysis revealed a mixture of hexagonal and cubic structures in the film, with crystallite sizes ranging from 11 nm to 18 nm. Schottky diodes fabricated on the thin films demonstrated specific electrical characteristics, including barrier height and carrier density, which changed after irradiation with alpha particles.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Physics, Applied
Johannes Engel, Kaushalya Jhuria, Debanjan Polley, Tobias Luehmann, Manuel Kuhrke, Wei Liu, Jeffrey Bokor, Thomas Schenkel, Ralf Wunderlich
Summary: A common technique for creating color centers in wideband gap semiconductors is ion implantation followed by thermal annealing. Typically, this annealing process takes place in a vacuum oven. In this study, we utilized annealing based on femtosecond laser pulses. By implanting fluorine ions at 54 keV and chlorine ions at 74 keV into diamond, and performing micrometer precise annealing using focused femtosecond laser pulses (800 nm +/- (30) nm) with varying pulse numbers and repetition rates, we successfully created shallow spots with color centers of different brightness.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Xiaorui Wang, Degang Zhao, Jiqiang Ning, Dapeng Yu, Shijie Xu
Summary: This article investigates the phenomenon of negative thermal quenching in the YL band of Si-doped GaN and concludes that it is caused by the thermal transfer of excited holes from shallow acceptors to deep acceptors. The YL lineshape is analyzed, and important physical parameters related to the YL process are determined. The position of the YL deep acceptor level is estimated.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
M. Klimenkov, M. Duerrschnabel, U. Jaentsch, P. Lied, M. Rieth, H. C. Schneider, D. Terentyev, W. Van Renterghem
Summary: Pure W material was neutron irradiated at temperatures ranging from 600°C to 1200°C, resulting in the formation of voids, dislocation loops, and W-Re-Os containing precipitates. The microstructure analysis revealed the detailed structure of these defects, including the size and distribution of voids, precipitates, and loops. Additionally, chemical and structural analysis showed that the defects were surrounded by a solid solution cloud enriched with Re and Os, and nanoscale chemical analysis identified differences in Re/Os segregation at and near the defects.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Optics
Radhe Shyam, Deepak Negi, Pargam Vashishtha, Govind Gupta, Apurba Das, Pamu Dobbidi, Srinivasa Rao Nelamarri
Summary: This study investigated the effects of swift heavy ion irradiation on the photoluminescence properties of (K, Na)NbO3 films, showing that an increase in ion fluence led to enhanced oxygen vacancies which in turn affected the defect-related emissions. The research also demonstrated an enhancement of sub-oxides and deep-traps in the films with higher ion fluence, impacting the decay lifetime of the materials.
JOURNAL OF LUMINESCENCE
(2021)
Article
Chemistry, Physical
M. Stachowicz, A. Wierzbicka, J. M. Sajkowski, M. A. Pietrzyk, P. Dluzewski, E. Dynowska, J. Dyczewski, K. Morawiec, S. B. Kryvyi, S. Magalhaes, E. Alves, A. Kozanecki
Summary: This study analyzed heteroepitaxially grown ZnO/MgO superlattices on a-oriented ZnO substrates. It found that the different crystalline structures of ZnO and MgO influence the abruptness of the interface and the retention of the wurtzite structure. The wurtzite structure can be retained in the MgO thin barriers, but it inevitably leads to non-uniform biaxial strains and interdiffusion of Mg from barriers to ZnO QW's. The complex strain/composition heterogeneities can be explained by the difference in vapor pressure between Mg and Zn elements and the high mobility of Mg atoms. A ZnMgO film of three monolayers size was created at the interfaces, which partly contributes to retaining the wurtzite structure of the coherently grown MgO layers.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
Xin Jin, Flyura Djurabekova, Miguel Sequeira, Katharina Lorenz, Kai Nordlund
Summary: In this study, we used a simulation approach to investigate the dechanneling induced by voids with different shapes in tungsten. We found that the dechanneling cross section of large voids can be described by the product of the minimum yield and the area projected from the void to the target surface, as suggested by analytical models. However, this method overestimates the dechanneling induced by small voids, and there are significant differences between voids and stacking faults in terms of dechanneling.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Physics, Applied
S. Magalhaes, J. S. Cabaco, O. Concepcion, D. Buca, M. Stachowicz, F. Oliveira, M. F. Cerqueira, K. Lorenz, E. Alves
Summary: The study demonstrates the importance of accurately determining the strain states of semiconductor compounds and introduces a new software called LAPAs. The lattice parameters and chemical composition of Al1-xInxN and Ge1-xSnx compounds grown on different substrates are calculated using the Bond's method and compared with results from x-ray diffraction. The findings show that broad peaks contribute significantly to the uncertainty in lattice parameters, and the inclusion of refraction correction has a small impact on the results. The differences between real space and reciprocal space methods are also discussed.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Instruments & Instrumentation
Przemyslaw Jozwik, Afonso Cacador, Katharina Lorenz, Renata Ratajczak, Cyprian Mieszczynsk
Summary: There is a long-standing interest in studying radiation damage caused by ion beams, which are present in space or the nuclear industry and used in materials modification. Rutherford Backscattering Spectrometry in channeling mode (RBS/C) is commonly employed to analyze the damage, but the presence of various defect types makes interpretation of RBS/C spectra challenging. To address this issue, the McChasy Monte Carlo simulation code was developed, which utilizes small simulation cells to analyze channeling data in crystals with different defect types. This study introduces a new feature of the code, a model of dislocation loops, and validates its effectiveness by analyzing RBS/C experiments performed at different beam energies for Eu-implanted GaN with an energy of 300 keV.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2023)
Article
Physics, Multidisciplinary
C. M. Vitor, E. Alves, R. C. da Silva, R. Mateus, J. Cruz, N. Catarino
Summary: In this study, ion beam analysis techniques were used to investigate the Be-related plasma-wall interactions. New data sets for the differential cross sections Be-9(He-3,p( i ))B-11 were obtained, and the results were found to be consistent with previous studies. A benchmarking measurement was performed to validate the results.
Article
Multidisciplinary Sciences
D. M. Esteves, A. L. Rodrigues, L. C. Alves, E. Alves, M. I. Dias, Z. Jia, W. Mu, K. Lorenz, M. Peres
Summary: Ion-beam-induced luminescence (IBIL) measurements were performed in Cr-doped β-Ga2O3, showing a strong enhancement of the Cr3+ luminescence upon ion irradiation. The effective cross-sections associated with the defect-induced IBIL enhancement and quenching processes were estimated through theoretical modelling. Thermoluminescence (TL) studies revealed that the TL emission corresponding to the Cr3+ luminescence can be activated by ion irradiation and quenched by annealing, suggesting the role of irradiation-induced defects.
SCIENTIFIC REPORTS
(2023)
Article
Materials Science, Multidisciplinary
Adeleh Mokhles Gerami, Juliana Heiniger-Schell, E. Lora da Silva, Messias S. Costa, Cleidilane S. Costa, Joao G. Monteiro, Jose J. Pires, Daniela R. Pereira, Carlos Diaz-Guerra, Artur W. Carbonari, Katharina Lorenz, Joao G. Correia
Summary: Lamellar alpha-MoO3 crystals were implanted with low fluence of radioactive (111)mCd ions at ISOLDE-CERN. The interaction between Cd impurity and oxygen vacancies in the lattice was studied using the time differential perturbed angular correlations nanoscopic technique. Modeling and simulations confirmed that interstitial Cd prevailed in the van der Waals gap and induced a polaron effect. The most stable defect configuration was found to be Cd-I with two O2 vacancies located at different planes.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Nuclear Science & Technology
Y. Zayachuk, N. Catarino, C. Smith, I. Jepu, C. Ayres, A. Widdowson, E. Alves, M. Rubel, JET Contributors
Summary: In this study, beryllium samples with co-deposits or surface cracks caused by melt damage were immersed into boiling water to simulate the impact of coolant water ingress into a tokamak. The results showed that there was no thermomechanical damage to the samples during exposure, and no measurable release of deuterium occurred. Only some degree of surface oxidation was observed, but no thick oxide films were formed.
NUCLEAR MATERIALS AND ENERGY
(2023)
Article
Chemistry, Multidisciplinary
R. Simoes, J. Rodrigues, C. M. Granadeiro, L. Rino, V. Neto, T. Monteiro, G. Goncalves
Summary: Luminescent lanthanide metal-organic frameworks (LnMOF) are proposed as a solution for anti-counterfeiting, using a quick-response (QR) code based on luminescent LnMOF-based composite. The composites exhibit specific optical properties that can only be unlocked using a sequence of stimulation.
MATERIALS TODAY CHEMISTRY
(2023)
Article
Materials Science, Coatings & Films
C. F. Adame, E. Alves, N. P. Barradas, P. Costa Pinto, Y. Delaup, I. M. M. Ferreira, H. Neupert, M. Himmerlich, S. Pfeiffer, M. Rimoldi, M. Taborelli, O. M. N. D. Teodoro, N. Bundaleski
Summary: In this study, a systematic characterization of deuterium-contaminated a-C coatings was performed to establish a correlation between hydrogen content and secondary electron emission properties. The results showed that hydrogen impurities increase the secondary electron yield (SEY) of a-C films. Mechanisms of contamination were also investigated, revealing a process involving target poisoning and physical sputtering. The maximum SEY (SEYmax) increased linearly with relative D/H amounts between 11% and 47%, and abruptly increased in the range of 47%-54% when the nature of the deposited films changed.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Engineering, Electrical & Electronic
A. Cacador, P. Jozwik, S. Magalhaes, J. G. Marques, E. Wendler, K. Lorenz
Summary: Ion implantation provides precise control over various parameters in material doping, but it also causes ion-induced damage. This study used Rutherford Backscattering Spectrometry in Channeling mode to analyze the defect profiles in GaN samples implanted with different fluences of Europium ions. The results showed that the damage increased with fluence in a complex manner, indicating the presence of multiple defect types and elaborate defect evolution mechanisms.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Instruments & Instrumentation
Cyprian Mieszczynski, Przemyslaw Jozwik, Kazimierz Skrobas, Kamila Stefanska-Skrobas, Renata Ratajczak, Jacek Jagielski, Frederico Garrido, Edyta Wyszkowska, Alexander Azarov, Katharina Lorenz, Eduardo Alves
Summary: In this work, the unique capability of the new version of the McChasy code (called McChasy2) to simulate experimental energy spectra delivered by Rutherford Backscattering Spectrometry in channeling direction (RBS/C) using large atomic structures (ca. 108 atoms) is presented. The focus is on the simulations of extended structural defects (edge dislocations and loops) formed inside nickel-based single-crystal alloys, which are widely studied and promising materials for high-temperature applications.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2023)
Article
Chemistry, Inorganic & Nuclear
Melani J. A. Reis, Ana T. Nogueira, Ana Eulalio, Nuno M. M. Moura, Joana Rodrigues, Dzmitry Ivanou, Paulo E. Abreu, M. Rosario P. Correia, Maria G. P. M. S. Neves, Ana M. V. M. Pereira, Adelio Mendes
Summary: A new series of Zn(II) and Cu(II)-based porphyrin complexes 5a and 5b, functionalised with carbazole units, were developed as hole-transporting materials (HTMs) in perovskite solar cells (PSCs). These complexes were obtained via nucleophilic substitution reaction or using C-N transition metal-assisted coupling. The study confirmed that Zn(II) complex 5a had better alignment with the perovskite valence band level and higher potential as an HTM compared to Cu(II) complex 5b. The photovoltaic performance of the optimized complexes showed improved characteristics, with a maximum power conversion efficiency (PCE) of 10.01% for 5a. These C-N linked porphyrin derivatives demonstrate promise as novel HTMs for efficient and reproducible PSCs.
DALTON TRANSACTIONS
(2023)
Article
Instruments & Instrumentation
Taisei Hayashi, Kensei Ichiba, Daisuke Nakauchi, Takumi Kato, Noriaki Kawaguchi, Takayuki Yanagida
Summary: In this study, Cr-doped Mg4Ta2O9 single crystals with different doping levels were synthesized using the floating zone method, and their photoluminescence and scintillation properties were evaluated. The results showed that Cr-doped Mg4Ta2O9 single crystals exhibited broad emission bands in the near-infrared region and showed scintillation characteristics within specific wavelength ranges. Additionally, the samples with different Cr doping levels demonstrated different lower detection limits based on the dose rate response function.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2024)
Article
Instruments & Instrumentation
S. Marouf, A. C. Chami, Y. Boudouma
Summary: This study develops a Monte Carlo simulation approach to describe proton-induced secondary electron emission in solids. Theoretical modeling based on the Mott's elastic scattering cross-section and Lindhard's dielectric function was used to calculate the double differential cross-section (DDCS) of excited electrons and describe electron transport in the medium. The results for aluminum show the angular and energy distributions of backscattered electrons for incident protons with energy below 25 keV at normal incidence, and the total electron emission yield also agrees well with available measurements.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2024)
Article
Instruments & Instrumentation
Weipeng Yan, Baojun Duan, Zijian Zhu, Yan Song, Guzhou Song, Jiming Ma, Binkang Li, Yucheng Liu
Summary: This article reports on the scintillation performance of Lithium-doped 2D (PEA)2PbBr4 perovskite single crystals synthesized at room temperature. The crystals exhibit fast decay time, high light yield, and high spatial resolution, making them highly promising for medical diagnostic applications.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2024)
Article
Instruments & Instrumentation
S. B. Vishwakarma, S. K. Dubey, R. L. Dubey, I. Sulania, D. Kanjilal
Summary: Investigations have been conducted on the implanted SiO2 thin film after thermal annealing using various analytical techniques. The results revealed the absence of vacancy defects, variations in vibrational modes and the formation of new structures. The photoluminescence intensity of the annealed SiO2 samples was higher, with a decrease in non-radiative defect centers and an increase in radiative Si:SiO2 interface states. Additionally, the presence of silicon nanoclusters formed after annealing resulted in an additional radiative recombination peak. Furthermore, the formation of new SiOx structures was observed after thermal annealing.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2024)
Article
Instruments & Instrumentation
M. Koshimizu, S. Kurashima, A. Kimura, M. Taguchi
Summary: By observing the scintillation time profiles of CeF3 under irradiations of pulsed beams with different LETs, we found that the initial decay was faster for higher LET, which is consistent with previous studies on other self-activated scintillators. This faster decay at higher LET can be explained by the competition between the scintillation caused by 5d-4f transition of Ce3+ ions and quenching due to the interaction between excited Ce3+ ions close to each other.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2024)
Article
Instruments & Instrumentation
Junjie Shi, Jianhong Hao, Fang Zhang, Qiang Zhao, Bixi Xue, Jieqing Fan, Zhiwei Dong
Summary: This study examined the neutralization process and beam quality of a hydrogen beam by emitting negative hydrogen ions to a hydrogen target. The findings showed that the neutralization efficiency was influenced by variables such as the transport distance, energy, and target gas density. However, the maximal neutralization efficiency was not affected by the density of the target gas or the energy of the negative hydrogen ions.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2024)
