Interaction Of Radiation Defects Research Articles

ИМПУЛЬСНЫЕ ХАРАКТЕРИСТИКИ КРЕМНИЕВЫХ СТРУКТУР С N-P ПЕРЕХОДОМ, ОБЛУЧЕННЫХ ПРОТОНАМИ

Currently, methods are being actively developed to create semiconductor structures with desiredproperties by irradiation with ionizing particles (radiation defect engineering). The interactionof radiation defects with impurities, dislocations and other structural defects causes a change in theproperties of semiconductors and semiconductor devices. Irradiation with protons makes it possibleto controllably create radiation defects with a distribution maximum in a pre-calculated region. Theaim of this work is to analyze the effect of irradiation with low-energy protons on the impulse characteristicsof silicon structures with an n+-p junction. The task is to determine the effective lifetime  ofcharge carriers in the space charge region (SCR) of the n+-p junction. The n+-p-p+-structures madeof silicon grown by the Czochralski method, irradiated from the side of the n+-layer by a low-energyproton flux at sample temperatures of 300 K and 83 K were studied. To measure the impulse characteristics,bipolar rectangular voltage pulses with a constant amplitude of 10 mV and a frequency of1 MHz were used. The experimental data are explained using models of nonstationary charge carriertransport in inhomogeneous semiconductors and the formation of radiation defects in silicon underthe action of protons. Depth distributions of the average number of primary radiation defects arecalculated: interstitial silicon, vacancies, divacancies created by one proton per unit length of theprojective path. It is shown that irradiation with protons with a dose of 1015 cm2 and an energy of40 keV does not change the value of , but with an energy of 180 keV creates a region with an effectivelifetime of 5.5108 s in the SCR of the n+-p junction.

The effects of neutron irradiation on the physicomechanical properties of refractory metals

Studying the interaction of radiation defects with defects in the crystal lattice in the initial state makes it possible to distinguish the contribution of each type of defect to changes in the physicomechanical properties of materials exposed to irradiation. When comparing the changes in the properties of the metals with the body-centered cubic (BCC) lattice (Mo, W, V, Nb) and hexagonal close-packed (HCP) lattice (Re), we see common features and differences in their behavior under irradiation: − both HCP and BCC crystals show an orientation dependence of their properties; at the same time, the metals with the BCC lattice are characterized by an increase in the size of the sample in all crystallographic directions, whereas, for the HCP crystals, the sample is narrowed along the <0001> direction, perpendicular to the plane with the closest packing of atoms, and expanded along other directions; − for the BCC samples, the elastic moduli decrease; for the HCP samples, the shear modulus increases significantly as a result of irradiation; − electrical resistance for the metals of Group 6 (Mo, W) and rhenium as a result of irradiation increases; for the metals of Group 5 (V, Nb), it decreases: this decrease in electrical resistance is associated with the release of interstitial impurity atoms to radiation defects; − for the BCC crystals, relaxation processes occur both in the unirradiated and irradiated samples, whereas, in the HCP crystals, only irradiation and post-irradiation annealing cause the temperature dependence of internal friction (TDIF) and the appearance of a relaxation maximum due to a change in the point symmetry of the defect; and − during isochronous annealings up to 0.7×Тm, behavior features associated with the crystal lattice structure are retained.

On increasing of integration rate of elements in a multi-level inverter

PurposeThe purpose of this paper is to analyze the redistribution of dopant and radiation defects to determine conditions which correspond to decreasing of elements in the considered inverter and at the same time to increase their density.Design/methodology/approachIn this paper, the authors introduce an approach to increase integration rate of elements in a three-level inverter. The approach is based on decrease in the dimension of elements of the inverter (diodes and bipolar transistors) due to manufacturing of these elements by diffusion or ion implantation in a heterostructure with specific configuration and optimization of annealing of dopant and radiation defects.FindingsThe authors formulate recommendations to increase density of elements of the inverter with a decrease in their dimensions.Practical implicationsOptimization of manufacturing of integrated circuits and their elements.Originality/valueThe results of this paper are based on original analysis of transport of dopant with account transport and interaction of radiation defects.

Defect evolution in a Ni[sbnd]Mo[sbnd]Cr[sbnd]Fe alloy subjected to high-dose Kr ion irradiation at elevated temperature

A candidate NiMoCrFe alloy (GH3535) for application as a structural material in a molten salt nuclear reactor was irradiated with 1 MeV Kr2+ ions (723 K, max dose of 100 dpa) at the IVEM-Tandem facility. The evolution of defects like dislocation loops and vacancy- and self-interstitial clusters was examined in-situ. For obtaining a deeper insight into the true nature of these defects, the irradiated sample was further analysed under a TEM post-facto. The results show that there is a range of different types of defects formed under irradiation. Interaction of radiation defects with each other and with pre-existing defects, e.g., linear dislocations, leads to the formation of complex microstructures. Molecular dynamics simulations used to obtain a greater understanding of these defect transformations showed that the interaction between linear dislocations and radiation induced dislocation loops could form faulted structures that explain the fringed contrast of these defects observed in TEM.

Interaction of radiation defects with nickel atom clusters in silicon

Based on infrared microscopic studies, we show that clusters of impurity nickel atoms are uniformly distributed over the entire volume of the silicon crystal; by varying the density of the clusters in silicon exposed to γ-radiation, it is possible to control the concentration of the electroactive atoms and the structure of the nickel clusters. It is shown that the presence of clusters in the lattice significantly increases the radiation resistance of the silicon.

Changes in the state of phosphorus atoms in the silicon lattice as a result of interaction with radiation defects

Interaction of radiation defects with phosphorus atoms in silicon crystals subjected to electron irradiation and thermal treatments was studied under conditions of various degrees of supersaturation with respect to the equilibrium concentration of impurities and point defects. It is shown that, in the course of silicon irradiation, the electron-dose dependences of the phosphorus concentration at the lattice sites (Ps) level off (tend toward a constant value). This constant value is governed by the irradiation temperature. The stages of recovery of the concentration Ps as a result of heat treatments correlate with temperature intervals of dissociation of the vacancy complexes. The results indicate that there are two processes. One process involves the interaction of dopant atoms with silicon self-interstitials and the emergence of interstitial complexes; i.e., this process corresponds to the radiation-stimulated decomposition of a supersaturated solution of an impurity as a result of point-defect generation and ionization. The other process consists in the recombination of interstitial impurities with vacancies at sufficiently high temperatures or in the annihilation of vacancies released during heat treatments with interstitial atoms incorporated into composite defect complexes with the involvement of phosphorus atoms.

DLTS investigation on the interaction of radiation defects with thermal defects in Czochralski p-Si

DLTS investigation on the interaction of radiation defects with thermal defects in Czochralski p-Si

The interaction of radiation defects and Pd-related centers in silicon

The defects, whose structures are well known (for example, the complex of oxygen and vacancy-A center), were introduced in the p+n junction samples with diffused Pd by irradiation of electrons, and their interaction was promoted by annealing. The existance of the energy level related to Pd in Si can lower the annealing temperature of A centers, but does not affect its generating rate. The level ETC related to Pd is the complex of the interstitial Pd and vacancy.

Interaction of radiation defects with the surface of silicon

The formation and annealing processes of radiation defects in bulk crystals and thin (≈︁ 1.2 μm) epitaxial layers of Si are studied. Czochralski grown (pulled) and vacuum float-zone n-type Si crystals with ϱ = 1 to 2 Ωcm as well as n-type Si epitaxial layers (∂ ≈︁ 1 Ωcm) grown on substrates of p-type Si, 400 pm thick (ϱ ≈︁ 10 Ωcm) are used. The samples are irradiated (T ⪷ 50 °C) by 640 MeV protons. Results are obtained from the analysis of the temperature dependences of the Hall coefficient at various steps of irradiation or 15 min isochronous annealing as well as from the spatial distributions (over the layer thickness) of the doping impurity and irradiation- and annealing-produced defect concentration. It is established that due to the interaction with the surface of irradiation-generated vacancies and interstitials as well as mobile defects and their components migrating at annealing, a number of peculiarities in radiation defect accumulating and annealing processes take place in epitaxial layers of Si as compared to bulk crystals: 1) Lower charge-carrier removal rates due to the low E-centre introduction efficiency whereby they are not the main compensating defects in thin layers whose thickness is comparable to the vacancy diffusion length; 2) sufficiently wide radiation defect annealing range; 3) effective production of multivacancy complexes under heat treatment near the surface. The results obtained are explained taking into account electric fields and long-range elastic stress fields near the surface. [Russian Text Ignored].

Interaction of radiation defects of different nature in n-Si at irradiation and annealing

Abstract Peculiarities in accumulating and annealing processes of 60Co γ-ray-induced radiation defects of vacancy (E-centers) and interstitial (interstitial carbon C1, complexes of substitutional carbon-interstitial carbon Ci-Cs) types due to their interaction with defect clusters being formed under heat treatment of n-Si preliminarily irradiated by fast neutrons have been studied.