Radiation Defect Formation Processes Research Articles

Influence of stress in epitaxial ferrite-garnet films on the processes of radiation defect formation and low-temperature aging of the ion-implanted layers

To study the effect of mechanical stresses on the defect formation processes in epitaxial garnet films and on the low-temperature aging of the implanted layer, YIG films of different thicknesses irradiated with B+ ions with an energy of 80 keV were used. The presence of elastic deformation energy, the magnitude of which depends on the film thickness, leads to differences in the disorder of the near-surface layers during ion implantation. After 15 years of low-temperature aging of ion-implanted ferrite-garnet films at room temperature, the appearance of all strain profiles becomes the same and does not depend on the thickness of the implanted films.

ВЛИЯНИЕ ПРИМЕСИ ГОЛЬМИЯ НА ПРОЦЕССЫ РАДИАЦИОННОГО ДЕФЕКТООБРАЗОВАНИЯ В n-Si

Effect of Holmium Impurity on the Processes of Radiation Defect Formation in n-Si

Photoluminescence Study of AlGaAs/GaAs after Focused Ion Beam Milling

Light-emitting devices of modern photonics are based on the semiconductor structures containing layers with various physical parameters. To preserve initial parameters during focused ion beam (FIB) lithography, it is necessary to take into account the processes of radiation defect formation. Radiation-induced defects in target play role of nonradiative recombination centers leading to photoluminescence (PL) quenching. In our work, the FIB impact on the photoluminescence were examined using PL spectroscopy of milled Al0.18Ga0.82As/GaAs double heterostructure. In order to exclude photoexcited carriers losses in emitter layer, an experiment with subbarrier photoexcitation was organized. Finally, we compare our experimental findings with theoretical data proposed by stopping and range of ions in matter (SRIM) calculation.

Dependence of the Carrier Removal Rate in 4H-SiC PN Structures on the Irradiation Temperature

The influence of 15 MeV proton irradiation temperatures (room temperature (RT) - 700 ° C) on the processes of defect formation in commercially available 4H-SiC JBS structures has been studied. It has been shown that the carrier removal rate does not depend on the irradiation temperature. At the same time, the irradiation temperature affected on the spectrum of introduced radiation defects. The conclusion about the possible influence of SiC crystal lattice structural defects on the processes of radiation defect formation has been made.

Mathematical modelling of radiation defect formation processes in the materials irradiated with protons and alpha particles

Metals and alloys still remain constructional, instrumental and other materials basis. An important factor in their properties formation are the crystalline grid nano-defects arising, in particular, in case of radiation. By the ionic bombing receiving high-quality, dense metal films and coverings on substrates could be realized. Such materials search and development rely on clear understanding nano-defects radiation creation mechanisms. In the work process of interaction protons and alpha particles with substance and radiation defects formations is considered. For calculation the cascade and probabilistic functions, the primary beaten-out atoms (PBOA) ranges, radiation defects concentration needs to execute approximating expression selection and to find approximation coefficients for interaction section. Interaction section for protons and alpha particles is calculated by Rutherford's formula. Analytical expression on cascade and probabilistic function taking into account energy losses for protons and alpha particles from recurrence relations for transition probabilities is received. The cascade and probabilistic function calculation algorithm, primary beaten-out atoms range, radiation defects concentration is given. G M T Detect language Afrikaans Albanian Arabic Armenian Azerbaijani Basque Belarusian Bengali Bosnian Bulgarian Catalan Cebuano Chichewa Chinese (Simplified) Chinese (Traditional) Croatian Czech Danish Dutch English Esperanto Estonian Filipino Finnish French Galician Georgian German Greek Gujarati Haitian Creole Hausa Hebrew Hindi Hmong Hungarian Icelandic Igbo Indonesian Irish Italian Japanese Javanese Kannada Kazakh Khmer Korean Lao Latin Latvian Lithuanian Macedonian Malagasy Malay Malayalam Maltese Maori Marathi Mongolian Myanmar (Burmese) Nepali Norwegian Persian Polish Portuguese Punjabi Romanian Russian Serbian Sesotho Sinhala Slovak Slovenian Somali Spanish Sundanese Swahili Swedish Tajik Tamil Telugu Thai Turkish Ukrainian Urdu Uzbek Vietnamese Welsh Yiddish Yoruba Zulu Afrikaans Albanian Arabic Armenian Azerbaijani Basque Belarusian Bengali Bosnian Bulgarian Catalan Cebuano Chichewa Chinese (Simplified) Chinese (Traditional) Croatian Czech Danish Dutch English Esperanto Estonian Filipino Finnish French Galician Georgian German Greek Gujarati Haitian Creole Hausa Hebrew Hindi Hmong Hungarian Icelandic Igbo Indonesian Irish Italian Japanese Javanese Kannada Kazakh Khmer Korean Lao Latin Latvian Lithuanian Macedonian Malagasy Malay Malayalam Maltese Maori Marathi Mongolian Myanmar (Burmese) Nepali Norwegian Persian Polish Portuguese Punjabi Romanian Russian Serbian Sesotho Sinhala Slovak Slovenian Somali Spanish Sundanese Swahili Swedish Tajik Tamil Telugu Thai Turkish Ukrainian Urdu Uzbek Vietnamese Welsh Yiddish Yoruba Zulu Text-to-speech function is limited to 200 characters Options : History : Feedback : Donate Close

Effect of the energy of recoil atoms on conductivity compensation in moderately doped n-Si and n-SiC under irradiation with MeV electrons and protons

Processes of radiation defect formation and conductivity compensation in silicon and silicon carbide irradiated with 0.9MeV electrons are considered in comparison with the electron irradiation at higher energies. The experimental values of the carrier removal rate at the electron energy of 0.9MeV are nearly an order of magnitude smaller than the similar values of the parameter for higher energy electrons (6–9MeV). At the same time, the formation cross-section of primary radiation defects (Frenkel pairs, FPs) is nearly energy-independent in this range. It is assumed that these differences are due to the influence exerted by the energy of primary knocked-on atoms (PKAs). As the PKA energy increases, the average distance between the genetically related FPs grows and, as a consequence, the fraction of FPs unrecombined under irradiation becomes larger. The FP recombination radius is estimated (∼1.1nm), which makes it possible to ascertain the charge state of the recombining components. Second, the increase in the PKA energy enables formation of new, more complex secondary radiation defects. At electron energies exceeding 15MeV, the average PKA energies are closer to the values obtained under irradiation with 1MeV protons, compared with an electron irradiation at the same energy. As for the radiation-induced defect formation, the irradiation of silicon with MeV protons can be, in principle, regarded as a superposition of the irradiation with 1MeV electrons and that with silicon ions having energy of ∼1keV, with the “source” of silicon ions generating these ions uniformly across the sample thickness.

Simulation of radiation-defect formation processes in heterostructures with self-assembled Ge(Si)/Si(001) nanoislands under neutron irradiation

TRISQD software is developed for the computer simulation of processes in which radiation defects are formed under the corpuscular irradiation of semiconductor heterostructures with lenticular nanoinclusions of various shapes. The computer program is used to study defect-formation processes in p-i-n diodes with the i region having a built-in 20-period lattice of self-assembled Ge(Si) nanoislands formed under irradiation with high-energy neutrons. It is found that the fraction of Ge(Si) nanoislands in which point radiation defects are formed under the impact of atomic-displacement cascades is ≤3% of their total number in the lattice. More than 94% of the defects are localized in the bulk of the p, n, and i regions of the diode and in silicon layers that separate sheets of Ge(Si) nanoislands.

Relationship between Markov Chains and Radiation Defect Formation Processes by Ion Irradiation

The work was performed within in the context of cascade?probabilistic method, the essence of which is to obtain and further application of cascade?probabilistic functions (CPF) for different particles. CPF make sense probability of that a particle generated at some depth h' reaches a certain depth h after the n-th number of collisions. We consider the interaction of ions with solids and relationship between radiation defect formation processes and Markov processes and Markov chains. It shows how to get the recurrence relations for the simplest CPF from the Chapman-Kolmogorov equations. In this case the particle does not change its direction of movement after the collision, the flow rate does not depend on time, and consequently, on the depth of penetration. We also obtained recurrence relations for the CPF with the energy loss of ions from the Kolmogorov-Chapman equations, the flow rate depends on the depth of penetration.

Irradiation Enhancement of Electrical Properties of Passive Impurities in Silicon Crystals

Radiation defect formation processes in silicon crystals for the cases when concentrations of electrical nonactive impurities (oxygen, carbon) prevail over main impurities determining siliconconductivity, are being covered in this paper. The role of interstitial atoms and vacancies, oxygen and impurity atoms in formation of radiation defects of A - and E-centers and divacancies, as well as their influence on electrical and optical properties ofsilicon crystals are shown. Energy levels of radiation defects in forbidden gap of silicon and their introduction rates were defined based on temperature dependencies of the concentrations of charge carriers at different irradiation doses. The capture probability of interstitial atoms and vacancies by main and passive impurities is taking into account. In addition to known A -and E-centers, along with disordered regions (clusters), a new radiation centers with energetic levels at

Vacancy generation in silicon in the temperature range 100–633 K under electron irradiation

The processes of radiation defect formation in Si with 1 MeV electron irradiation in the temperature range 100–633 K have been investigated. It is established that the generation efficiency of vacancies λV increases with temperature, then starts to saturate at temperatures of 250 K and finally stays constant at T>300 K. It is shown that at high temperatures, the λV dependence can be caused by the additional scattering of “hot” interstitial atoms on acoustical and optical phonons, the numbers of which increase with the temperature. An explanation, based on the creation of quasi-molecule of “hot” interstitial and lattice atoms, is proposed.

Radiation defect formation processes as a method for activation of red phosphorus in the Trofimov-Gusarova reaction

A new approach is discussed for modifying the reactivity of elemental phosphorus by controlled defect formation in its structure, and the application of this methodology in the synthesis of organophosphorus compounds.

Role of sodium in radiation defect formation in CsI crystals

Radiation defect formation processes in large dimension CsI crystal scintillators have been considered. It is shown that F-centers are efficiently formed in crystals doped with CO 3 2− and OH − ions. Sodium ions harden CsI crystals against radio-chemical reactions of F-centers, and HCO 3 − ion formation. The use of sodium as a co-activator to increase the radiation stability of CsI(Tl) crystals has been considered.

Tie Effect of Rare-Earth Elements on the Entroy of Radiation Defects Ionization in N-Type Go

ABSTRACTTe analyses of the processes of radiation defect formation in germanium doped with phosphorus in the presence of rare-earth element neodimium and without it has been carried out.It has been shown that the presence of neodimium in n-Ge results in the change of enthalpy and entropy of the major radiation defect ionization (complex with the level being near EB-0.20 eV). The change of enthalpy by 0.03-0.04 eV as well as more than six fold increase of entropy of the complex ionization in Ge:Nd has been stated to be connected with the local deformation of the lattice around defect formed in the process of irradiation.

The effect of grown-in structural imperfections on the radiation defect formation and annealing in dislocation-free silicon

The processes of radiation defect formation and annealing in dislocation-free n-type Si (ϱ = 100 Ω cm) grown by the float-zone technique in argon atmosphere or in vacuum are studied. In the latter case the ingot is grown at a varying rate and therefore contains A-, A + B-, and D-type microdefects in different parts. Crystals obtained in argon atmosphere do not involve microdefects identified by selective etching. The temperature dependences of the charge carrier lifetime (τ) and the Hall coefficient (RH) are measured. The variation in τ and RH after 60Co γ-ray irradiation at T = 330 K is found to be due to the accumulation of E-centres with the level Ec −0.43 eV. However, the E-centre introduction efficiency and annealing temperature in Si grown in argon atmosphere as well as in crystals with A + B-type microdefects are lower than in control Si with small content of dislocations (ND = 1 × 104 cm−2) where microdefects are absent. It is concluded that under certain growing conditions (gaseous atmosphere, growth rate, axial temperature gradient) of dislocation-free crystals, shallow (according to the estimates of 10 to 20 atoms) interstitial-type inclusions unidentified by selective etching can be formed in their bulk which produce strain fields around themselves and thereby are surrounded by an impurity atmosphere. Affected by the strain fields induced by inclusions, primary radiation defects migrate directedly towards them whereby accumulation of secondary complexes occurs around inclusions within the impurity atmosphere. For the same reason the E-centre formation efficiency in crystal matrix decreases and their annealing parameters change due to the effect to strain fields. Inclusions are assumed to be predecessors (fragments) of B- or D-type microdefects. [Russian Text Ignored].

Influence of irradiation temperature on radiation defect accumulation in silicon

The processes of radiation defect formation in n-type silicon are studied at various irradiation temperatures (Tirr = 20 to 400°C) during 640 MeV proton or 10 MeV electron bombardment. The results are obtained from the analysis of the temperature dependences of charge carrier concentration in crystals irradiated at various temperatures and investigating samples (which are not irradiated but subjected to similar thermal treatment). It is established that production efficiencies for main radiation defects (A-, E-centres, divacancies, complexes of carbon–oxygen-divacancy) are complicated functions of Tirr, however the form of these functions appear to be different for the two types of irradiation used. The results obtained are interpreted taking into account the fact that during cascade defect formation (in the case of proton irradiation) the effect of Tirr is due to the probabilities of secondary processes (dissociation and formation of complexes) changing with temperature, while in the case of diffusive mechanism (electron irradiation) the irradiation temperature Tirr has also an influence on the direct annihilation of Frenkel pairs generated by irradiation. [Russian Text Ignored].