Experimental investigation of bubble occurrence and locality distribution of bubble detectors bombarded with high-energy helium ions

Large-sized bubble detectors with microscopic droplets of superheated liquids of dichlorodifluoromethane (Freon-12), dichlorotetrafluoroethane (Freon-114), tetrafluoroethane (Freon-134a), and mixture of Freon-12 and Freon-114, respectively, were irradiated with 150 MeV/amu helium ions at the HIMAC accelerator in NIRS, Chiba, Japan. Distributions of bubbles produced by the helium ions have been studied in each type of the detectors. The origin of the bubbles has been investigated. The detection efficiency of each type of the bubble detectors for helium ions with respect to the energy of the ions has been obtained. The phenomenon of bubble occurrence and its possible applications to the determination of He intensity from accelerators, research of track formation mechanism, energy loss straggling and neutron detection in the space and at higher altitude are discussed.     

Depth distribution of SiD and SiD2 complexes in silicon bombarded by 10 keV D+ 2 ion

Abstract

A secondary ion mass spectrometry (SIMS) and a neutral molecule mass spectrometry (NMMS) study of deuterium trapping in a single crystalline silicon as a result of ion irradiation at fluences 10^16--10¹⁸ cm-² are presented. An attempt has been made to observe the formation and evolution of defect profiles containing one or two deuterium atoms (SiD- and SiD₂-complexes). The proposed model of radiation-induced sequential reactions describes satisfactorily the accumulation of SiD- and SiD₂-complexes and the reemission of D₂-molecules.     

Spatial distribution, build-up, and annealing of radiation defects in silicon implanted by high-energy krypton and xenon ions

An x-ray diffraction study of defect formation in silicon irradiated by Kr⁺ (210 MeV, 8×10¹²−3×10¹⁴ cm⁻²) and Xe⁺ (5.6 BeV, 5×10¹¹−5×10¹³ cm⁻²) ions is reported. It has been established that irradiation produces a defect structure in the bulk of silicon, which consists of ion tracks whose density of material is lower than that of the host. The specific features of defect formation are discussed taking into account the channeling of part of the ions along the previously formed tracks and the dominant role of electron losses suffered by the high-energy ions. It is shown that the efficiency of incorporation of stable defects by irradiation with high-energy ions is lower than that reached by implanting medium-mass ions with energies of a few hundred keV. Fiz. Tverd. Tela (St. Petersburg) 40, 1627–1630 (September 1998)     

SIMS of silicon bombarded with Sb m + cluster ions

The emission of Si _n ⁺ (n = 1–11) cluster ions and Si _n X _m ⁺ (X stands for B or Sb) polyatomic ions when bombarding a single silicon crystal with Sb _m ⁺ (m = 1–4) cluster ions with energies E ₀ = 3–12 keV is studied. Considerable nonadditive enhancement of the yield of Si _n ⁺ cluster ions and most polyatomic ions is observed when the number of atoms in the bombarding cluster ions is increased. The sensitivity enhancement factor for detecting boron impurities is as high as 50 when the cluster-SIMS-molecule technique is applied.     

Residual defects in high-energy B-, P- and As-implanted Si by rapid thermal annealing

The annealing behavior of secondary defects generated in 2 MeV B- and P-, and 1 MeV As-implanted (100) Si with a dose of 5×10¹⁴ ions/cm² has been investigated after rapid thermal annealing (RTA) treatment using cross-sectional TEM observations. The results are compared with ones obtained by furnace annealing (FA) treatment. RTA is more effective than FA for the defect density reduction of deep defects existing beyond 2 m depths from the surface in B- and P-implanted layers. However, when a dislocation loop diameter is close to the substrate surface, as in the case of As implantation, the loops climb up to the surface by 1250 °C RTA. Moreover, repeated RTA is effective for the suppression of secondary defect growth in B- and P-implanted layers, while there is no difference in defect density or configuration for As implantation between repeated and simple RTA.     

Photon emission from clean and oxygenated Si and SiO2 surfaces bombarded by 5 keV krypton ions

The effect of oxygen on the light emission from a Si (1 0 0) semiconductor bombarded by energetic Kr⁺ ions has been studied in the 200–300 nm wavelength range. The influence of oxygen was verified by studying the optical spectra of SiO₂ bombarded under similar experimental conditions. It has been found that the measured intensities of the emitted photons are always higher in the presence of oxygen, even higher than those obtained for SiO₂. The electron-transfer model can explain our experimental observations. We do believe that in the presence of oxygen, an intermediate structure of silicon sub-oxide SiO_X<2 is formed on silicon surface, which is responsible for the increase of photon emission. In addition, the radiative dissociation process and breaking of chemical bond seems contribute to the enhancement of emitted photons intensity.     

Thermo,Iono and photoluminescence properties of 100 MeV Si7+ ions bombarded CaSiO3:Eu3+ nanophosphor

This paper reports on the thermo (TL), iono (IL) and photoluminescence (PL) properties of nanocrystalline CaSiO₃:Eu³⁺ (1–5 mol %) bombarded with 100 MeV Si⁷⁺ ions for the first time. The effect of different dopant concentrations and influence of ion fluence has been discussed. The characteristic emission peaks ⁵D₀→⁷F_J (J=0, 1, 2, 3, 4) of Eu³⁺ ions was recorded in both PL (1×10¹¹–1×10¹³ ions cm^?2) and IL (4.16×10¹²–6.77×10¹² ions cm^?2) spectra. It is observed that PL intensity increases with ion fluence, whereas in IL the peaks intensity increases up to fluence 5.20×10¹² ions cm^?2, then it decreases. A well resolved TL glow peak at ～304 °C was recorded in all the ion bombarded samples at a warming rate of 5 °C s^?1. The TL intensity is found to be maximum at 5 mol% Eu³⁺ concentration. Further, TL intensity increases sub linearly with shifting of glow peak towards lower temperature with ion fluence.     

Surface properties of germanium bombarded by nitrogen ions

Results are given for ions of energy 1800 eV. Measurements have been made of the rate of surface recombination and of the surface conductivity for specimens of specific resistance 10 and 40 ohmcm. The results are interpreted in terms of donor level production, in agreement with earlier work. Trapping curves derived from the surface conductivity are used to deduce the position of the donor levels relative to the middle of the forbidden band.     

Emission of quasi-thermal ions from a solid bombarded by cluster ions

Comparative studies of the emission of quasi-thermal atomic and cluster ions from V, Nb, Ta, Au, and In targets bombarded by cluster ions Au _m ⁻(m = 1–9), as well as from Si and Bi targets bombarded by cluster ions Au _m ⁻(m = 1–9) and Bi _m ⁻(m = 1–5), with energy E ₀ ranging from 6 to 21 keV are carried out. In the case of bombardment by heavy cluster ions, the fraction of the quasi-thermal component in the energy spectra of sputtered atomic ions reaches 50 (for V, In, and Au), 70 (Nb), or more than 90% (Ta). In addition, quasi-thermal ions play a considerable part in the emission of small cluster ions Au₂⁺, In₂⁺, In₃⁺, and Bi _n ⁺(n = 2–7). The results of the generalizing investigation favor the presence of thermal spike conditions at cluster bombardment and their appreciable contribution to the emission of atomic and small cluster ions.     

Synthesis of nano-sized SiC precipitates in Si by simultaneous dual-beam implantation of C+ and Si+ ions

Nanometer-sized SiC precipitates were synthesized in situ in Si by simultaneous implantation of two ion beams of C⁺ and Si⁺ ions. The results of simultaneous dual-beam implantation are compared with those of sequential dual-beam ion implantation and of single-beam C⁺ ion implantation. Remarkable differences are observed regarding the content and the crystal quality of SiC precipitates as well as the defect structure of the Si substrate. The SiC precipitation during dual-beam synthesis is found to depend on the ion energy of the second beam and on the implantation mode, simultaneous or sequential. For suitable implantation conditions, simultaneous dual-beam synthesis can improve the in situ SiC formation in comparison to the single-beam synthesis. A higher density of SiC precipitates with better crystal quality was observed, whereas their size was not changed. The second ion beam enables a shift in the dynamic equilibrium of constructive and destructive processes for SiC formation. A model is proposed assuming that SiC precipitation preferentially proceeds in regions with vacancy defects. The implantation process itself creates vacancy-dominated and also interstitial-dominated regions. The balance of the local point-defect composition is shifted under the second ion beam. In this way, the conditions for SiC precipitation can be modified. Received: 18 February 2002 / Accepted: 17 May 2002 / Published online: 17 December 2002 RID="*" ID="*"Corresponding author. Fax: +49-351/260-3411, E-mail: koegler@fz-rossendorf.de     

Experimental investigation of the energy distribution of sputtered excited target atoms bombarded by medium-energy ions

In this paper we experimentally investigate the parameter dependence of a model energy distribution of excited potassium atoms, knocked out by bombarding a KCl monocrystal with normally incident Ar⁺ ions, on the ion energy and the partial oxygen pressure in the chamber. On the basis of the obtained results a model of the energy distribution is proposed that corresponds to the kinetic formation mechanism for the excited atoms during the sputtering of the target.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 9–12, March, 1985.     

Investigation of the dose dependence of the amorphization of a Si(111) surface bombarded with low-energy Na+ ions

A comparative analysis of the results of experiments on Si(111) surface amorphization by Na+ ions and earlier works on simulation of the process is carried out. The calculated parameters of the model satisfactorily explain the experimental characteristics throughout almost the entire energy range of E _i = 100–1200 eV, except for the region of dominant silicide formation (300–500 eV) not considered by the formalism of the used program.     

Sputter yields in diamond bombarded by ultra low energy ions

Artificial diamond is an ideal material for high power, high voltage electronic devices, and for engineering use in extreme environments. Diamond process development requires parallel development in characterization techniques such as ultra low energy SIMS (uleSIMS), especially in the ability to depth profile for impurities and dopants at high depth resolution.As a contribution to the background knowledge required, we have measured the sputter yields of single crystal high pressure high temperature (HPHT) diamond using O₂⁺, Cs⁺ and Ar⁺ primary ions in the energy range 300 eV to 2 keV. We compare these with yields for silicon and GaAs. We show that the erosion rates with oxygen are ∼10 times what would be expected from ballistic processes and essentially energy independent in the measured range. This result agrees with the anomalously high sputter yield observed in the ion etching context. Conversely, positive ion yields for elements such as boron are very low in comparison with silicon. This points to a reactive ion etching process liberating CO or CO₂ rather than sputtering as the principal erosion process.This is both problematic and beneficial for SIMS analysis. Oxygen can be used to reach buried structures in diamond efficiently, and the effects of the near-normal incidence beam are planarizing as they are in silicon. Conversely, since positive ion yields are low, alternative probes or strategies must be found for high sensitivity profiling of electropositive elements.     

MeV Al+ and Al2+ ions implantation in Si(100): surface roughness and defects in the bulk

This paper deals with the implantation of high-energy (1.0–3.0 MeV) atomic and molecular Al⁺ ions in Si(100) to a fluence of 5×10¹⁴ Al atoms/cm² at room temperature. The molecular effect, i.e. the increase of the displacement yield compared with the sum of the atomic yields, and the damage formation as well as defect behaviour after annealing have been investigated. A detailed experimental study has been made of the evolution of extended secondary defects which form during thermal anneals of Al⁺ or Al₂ ⁺ irradiated silicon. The samples have been examined using combined Rutherford backscattering and channeling experiments together with transmission electron microscopy observations. The surface structure of the implanted wafers has been measured by atomic force microscopy. The results for the implantation-induced roughness at the Si surface, resulting from Al⁺ or Al₂ ⁺ irradiation at the same energy/atom, total atomic fluence, flux rate, and irradiation temperature, are presented and discussed. Received: 19 August 1999 / Accepted: 20 October 1999 / Published online: 23 February 2000     

Ionization-Excitation of helium-like ions by high-energy electrons

The differential and total cross sections are calculated for the ionization of helium-like ions that is accompanied by the excitation of residual ions to ns states owing to an electron impact. Nonrelativistic perturbation theory in electron–electron interaction with Coulomb functions used for a zero-order approximation underlies these calculations. The expressions obtained in this way have a universal character. They are applicable at moderate values of the target charge number Z and high energies of incident electrons. A comparison with total cross sections calculated for the helium atom within various theoretical approaches is performed.     

Soft X-ray amplification by Li-like Al10+ and Si11+ ions in recombining plasmas

Experimental studies of soft X-ray lasers were carried out on the six-beam laser facility and the LF 12 laser facility of SIOM. Using a home-made one-dimensional spatially resolved grazing incidence grating spectrograph, XUV amplification has been observed in Li-like aluminum and silicon ions, by irradiation of slab targets with a line-focused laser. Based on time-integrated measurement, gain coefficients are 3.1 cm^–1 for the 105.7 Å 5f–3d transition in Li-like Al ions, and 1.5 cm^–1 and 1.4 cm^–1 for the 88.9 Å 5f–3d and the 87.3 Å 5d–3p transitions in Li-like Si ions, respectively. The maximum gain × length products (GL) are about 2.5.     

Calculation of the heat deposition and temperature distribution of the target bombarded by high-energy protons using Monte Carlo simulation and finite element method

The Monte Carlo simulation and the finite element methods have been used to calculate the heat deposition and temperature distribution in tungsten plate target when the target is bombarded by high-energy protons from the accelerator with nuclear power of 100 kW. The results show that the heat deposition in the target, reflector and shield will be 48 kW, 15 kW and 11 kW, respectively, and the highest temperature in the target plates will be lower than 100℃ when the surfaces of plates are cooled by water.     

Secondary ion emission under the bombardment of Si by multiply charged Si q+ ions

The spectra of secondary ion emission under the bombardment of a B-doped Si target by multiply charged Si ^q+ ions (q = 1?C5) have been studied in the energy range of 1 to 10 keV per unit of charge. A multifold increase in the yield of secondary cluster Sk _n ⁺ ions, multiply charged Si ^q/+ ion (q = 1?C3), and H⁺, C⁺, B⁺, Si₂N⁺, Si₂O⁺ is observed as the charge of the multiply charged ions increases. The increase in the yield of secondary ions with increasing charge of the multiply charged-ion charge is most significant for ions with relatively high ionization potentials.     

Sequence of structural-phase states during implantation of C+, N+, and Si+ ions into molybdenum

The sequence of structural-phase changes in the surface layer of molybdenum during pulsed implantation of N⁺, C⁺, and Si⁺ ions has been studied. At radiation doses 5·10¹⁶ cm^–2 we detected qualitatively similar structural-phase transformations with the formation of highly dispersed secondary-phase particles (nitrides, carbides, and silicides), dislocations, point defects, and clusters of defects. At radiation doses (1–2)·10¹⁷ cm^–2 implantation of C⁺ and Si⁺ ions causes amorphization of the surface layer; nitrogen implantation is accompanied by the formation of continuous layers of the nitride phase on the surface.Siberian Physicotechnical Institute at the V. D. Kuznetsov State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 3–9, February, 1994.