Comparison study of the charge density distribution induced by heavy ions and pulsed lasers in silicon

Heavy ions and pulsed lasers are important means to simulate the ionization damage effects on semiconductor materials. The analytic solution of high-energy heavy ion energy loss in silicon has been obtained using the Bethe-Bloch formula and the Kobetich-Katz theory, and some ionization damage parameters of Fe ions in silicon, such as the track structure and ionized charge density distribution, have been calculated and analyzed according to the theoretical calculation results. Using the Gaussian function and Beer＇s law, the parameters of the track structure and charge density distribution induced by a pulsed laser in silicon have also been calculated and compared with those of Fe ions in silicon, which provides a theoretical basis for ionization damage effect modeling.     

Large energy-loss straggling of swift heavy ions in ultra-thin active silicon layers

Monte Carlo simulations reveal considerable straggling of energy loss by the same ions with the same energy in fully-depleted silicon-on-insulator (FDSOI) devices with ultra-thin sensitive silicon layers down to 2.5 nm. The absolute straggling of deposited energy decreases with decreasing thickness of the active silicon layer. While the relative straggling increases gradually with decreasing thickness of silicon films and exhibits a sharp rise as the thickness of the silicon film descends below a threshold value of 50 nm, with the dispersion of deposited energy ascending above ±10%. Ion species and energy dependence of the energy-loss straggling are also investigated. For a given beam, the dispersion of deposited energy results in large uncertainty on the actual linear energy transfer (LET) of incident ions, and thus single event effect (SEE) responses, which pose great challenges for traditional error rate prediction methods.     

Investigation of the lateral spread of erbium ions implanted in silicon crystal

The erbium ions at energy of 400 keV and dose of 5×10 15 ions/cm 2 were implanted into silicon single crystals at room temperature at the angles of 0,45 and 60.The lateral spread of 400 keV erbium ions implanted in silicon sample was measured by the Rutherford backscattering technique.The results show that the measured values were in good agreement with those obtained from the prediction of TRIM’98 (Transport of Ions in Matter) and SRIM2006 (Stopping and Range of Ions in Matter) codes.     

Long Lifetime State of Shallow Donor Centres for Silicon Based THz Sources

Impurity centres in high purity silicon with ionization energies 38.32 and 40.09meV are observed by photothermal ionization spectroscopy measurements. Their typical shallow donor characteristics are approved by good agreement with theoretic evaluation under varying magnetic fields. The 2p0 state lifetime of one donor centres are more than 3 times longer than that of phosphorus in the same silicon sample. Compared to phosphorus which has been already successfully exploited to produce silicon-based THz radiations, this shallow donor centre has a pronounced enhancement on lifetime and quality factor of population inversion level. Hence, silicon with this donor centre would be a potential excellent candidate to develop improved silicon-based THz sources.     

Secondary Beam Fragments Produced by 200 and 400 MeV/u ^12C^6＋ Ions in Water

Based on the GEANT4 toolkit, we study the transportation of nucleons and nuclei in tissue-like media. The fragmentation of projectile nuclei and secondary interactions of produced nuclear fragments are considered. Livermore data is used to calculate electromagnetic interaction of primary and secondary charged particles. We validate the models using experimental data of 200 MeV/u and 400 MeV/u carbon ions, interacting with tissue equivalent materials of water. The model can well describe the depth-dose distributions in water and the doses measured for secondary fragments of certain charge and certain mass number. The secondary beam fragments produced by 200 MeV/u and 400 MeV/u ^12C^6＋ ions in water are investigated using the model. When the primary nuclei are in water, several neutron production mechanisms are involved. The light charged particles （p, d, t, ^3He and ^4He） and fast neutrons contribute to the dose tail behind the Bragg peak. The ^11C fragments which may be the most suitable nuclei for monitoring the energy deposition in carbon-ion therapy are also discussed.     

离子辐照单晶Si损伤效应的研究

回顾了低能离子注入单晶Si经由核弹性碰撞引起的损伤特征及其常规的研究方法,介绍了快重离子辐照单晶Si经由电子能损引起的损伤特点及研究现状,并对该领域的研究作了展望. The radiation damage in silicon induced by low energy ion implantation was briefly reviewed together with a short introduction to the common techniques in the area. The damage characteristics of swift heavy ion irradiation in silicon and its investigations were introduced with emphasis on the effects induced by processes of electronic energy losses. It is shown that swift heavy ion can induce defects far beyond the projected range and up to 28 MeV/μm the electronic energy ...     

Formation of two-dimensional photonic-crystal structures in silicon for near-infrared region using fine focused ion beams

One of the two variants of producing two-dimensional photonic crystals in silicon is the formation of ordered macropore structures in a silicon substrate. The characteristic pore dimensions (the diameter and the wall thickness between pores) determine the wavelength range in which such a pore structure exhibits the properties of a photonic crystal. For the near-infrared region, these dimensions approach 1 μm or fall in a submicron region. An ordered structure of macropores with such dimensions is formed in this work using fine focused ion beams to provide the stimulating effect of implanted ions on pore nucleation in given sites on the silicon substrate surface. Pores are shown to nucleate at sites subjected to ion irradiation even at a low implantation dose (2×10¹³ ion/cm²). A model describing the orienting effect of ion irradiation on pore nucleation is proposed. __________ Translated from Fizika Tverdogo Tela, Vol. 46, No. 1, 2004, pp. 35–38. Original Russian Text Copyright ? 2004 by Vyatkin, Gavrilin, Gorbatov, Starkov, Sirotkin.     

Incident particle range dependence of radiation damage in a power bipolar junction transistor

The characteristic degradations in silicon NPN bipolar junction transistors(BJTs) of type 3DD155 are examined under the irradiations of 25-MeV carbon(C),40-MeV silicon(Si),and 40-MeV chlorine(Cl) ions respectively.Different electrical parameters are measured in-situ during the exposure of heavy ions.The experimental data shows that the changes in the reciprocal of the gain variation((1/β)) of 3DD155 transistors irradiated respectively by 25-MeV C,40-MeV Si,and 40-MeV Cl ions each present a nonlinear behaviour at a low fluence and a linear response at a high fluence.The(1/β) of 3DD155 BJT irradiated by 25-MeV C ions is greatest at a given fluence,a little smaller when the device is irradiated by 40-MeV Si ions,and smallest in the case of the 40-MeV Cl ions irradiation.The measured and calculated results clearly show that the range of heavy ions in the base region of BJT affects the level of radiation damage.     

Molecular dynamic simulation of secondary ion emission from an Al sample bombarded with MeV heavy ions

Spluttering yields and kinetic energy distributions (KED) of Al atomic ions ejected from a pure aluminium sample under MeV silicon ion bombardment were simulated with the molecular dynamic method.Since the electronic energy loss Se is much higher than the nuclear energy loss Sn when the incident ion energy is as high as several MeV,the Se effect was also taken into consideration in the simulation.It was found that the simulated sputtering yield fits well with the experimental data and the electronic energy loss has a slight effect at incident ion energies higher than 4MeV.The simulated secondary ion KED spectrum is a little lower in the peak energy and narrower in the peak width than that in the experiment.     

微团簇HD^＋的形成机理及束缚能实测

文内报告了１５０９６５ＭｅＶＨＤ＋离子微团簇经库仑爆炸在０°方向生成碎片Ｈ＋和Ｄ＋能谱的测量。获得ＨＤ＋的最可几束缚能实测值为１１４８ｅＶ。较详细地讨论了ＨＤ＋在高频离子源中的形成机理     

Spectroscopic Study of the Growth Mechanism of Silver Microclusters

Polymer-protected silver microclusters have been obtained by room-temperature alcoholic reduction of metal ions in presence of a polymeric stabilizer (i.e., poly(N-vinyl-2-pyrrolidone) (PVP)). The method allows one to prepare bulk quantities of the material with a control of size from a molecular level. Spectrophotometric monitoring technique has been employed to investigate the influence of the aging of the protective PVP layer on the microcluster growth rate, under different reaction temperatures and PVP/ethylene glycol weight ratios. The aging time of the polymeric stabilizer solution has been found to play a fundamental role in the reproducibility of the microcluster growth kinetic. In addition, the microcluster growth process has resulted governed by a diffusion-controlled mechanism.     

Time-dependent quantum model of recharge of heavy ions and shell effects in angular distributions at channeling of nuclei in a silicon crystal

The model of recharge of heavy ions, based on the use of a pseudopotential and the three-dimensional time-dependent Schrödinger equation has been developed. The angular distributions of Y ions with initial energies of 60 and 140 MeV, transmitted through a thin silicon crystal in the axial channeling mode, are explained.     

Effect of the ionization energy loss density of high-energy bismuth,krypton, and xenon ions on the development of hydrogen blisters in silicon

Radiation-induced athermal hydrogen removal from single-crystal silicon subjected to irradiation by high-energy heavy Bi⁺ (E = 710 MeV), Kr⁺ (E = 85 and 250 MeV), and Xe⁺ (130 MeV) ions is detected experimentally. The decrease in the hydrogen concentration depends on the specific ionization energy losses of high-energy heavy ions. At high specific ionization losses of Bi⁺ ions with E = 710 MeV (22.5 keV/nm), the hydrogen concentration decreases to a level at which blisters cannot be observed in an optical or electron microscope (which is likely to be 1 at % hydrogen at the peak of the calculated hydrogen concentration profile). At medium specific ionization losses of Xe⁺ ions with E = 130 MeV (12.5 keV/nm) and Kr⁺ ions with E = 250 and 85 MeV (9.5 and 8.5 keV/nm, respectively), the hydrogen concentration decreases to a level that does not affect blister formation but determines the blister failure (flaking) conditions.     

MeV高能B+离子注入Si中二次缺陷的抑制与消除

本文研究了MeV高能B⁺离子注入Si中二次缺陷的退火行为。提出一种新型的双重注入退火方法,抑制或消除了MeV高能B⁺离子注入Si样品中的二次缺陷。还对这种二次缺陷的被抑制与被消除的物理机制进行了讨论。 关键词：     

Resonant coherent excitation of 94 MeV/u Ar17+ ions in the $$(2\bar 20)$$ planar channel of a silicon crystal

The charge exchange and characteristic x-radiation of channeled ions under resonant coherent excitation are simultaneously described in terms of the density matrix formalism. The survival fraction of 94 MeV/u Ar¹⁷⁺ ions in the \((2\bar 20)\) planar channel of a silicon crystal is calculated, and the angular distribution of x-ray emission of these ions is analyzed.     

Energy deposition distributions caused by fast neutrons in converter type silicon detectors

Polyethylene converter silicon detectors have been developed as part of a dosimetry system for the application in neutron fields. Signals have been investigated which are mainly caused by reactions occurring when neutrons hit the PE converter or the silicon diode directly. In this work, neutron interactions in the components of a PE converter silicon sensor have been calculated to determine energy deposition distributions for neutron energies from 1.2 v MeV to 14.8 v MeV. Experiments in quasi-monoenergetic neutron fields have been performed. For the simulation of the neutron interactions with the detector layers, the GSF neutron interaction code NISD has been applied. The transport of ions has been calculated separately by means of the program TRIM. It has been shown that by the use of these concepts and models, a rather good agreement of measured and computed pulse height distributions can be obtained and, consequently, the response of converter type detectors to neutron radiation can be determined.     

Probing a cooled beam of decelerated highly-charged heavy ions extracted out of the ESR by a channeling experiment

A cooled beam of decelerated highly-charged heavy ions is slowly extracted out of the cooler and storage ring ESR, by combining the deceleration technique and the charge exchange extraction mode. The quality of the external ion beam is tested by a channeling experiment. Bare Au⁷⁹⁺ ions are injected into the ESR at an energy of 360 MeV/u, decelerated to 53 MeV/u, and finally cooled strongly in the electron cooler. By breeding of neighboring charge state ions via radiative recombination in the electron cooler H-like ions are produced. The H-like ion fraction is extracted out of the storage ring. This extracted Au⁷⁸⁺ ion beam is probed by a channeling experiment measuring the extinction rate of the projectile Kα X-ray yield around the [110] axis of a thin silicon crystal. This revised version was published online in August 2006 with corrections to the Cover Date.     

Semi-empirical calculations for the ranges of fast ions in silicon

A semi-empirical method is proposed to calculate the ion ranges in energy region E?=?0.025–10?MeV/nucleon. The dependence of ion ranges on the projectile nuclear charge, mass and velocity is analysed. The calculations presented for ranges of ions with nuclear charges Z?=?2–10 in silicon are compared with SRIM results and experimental data.     

Ion-beam formation and track modification of InAs nanoclusters in silicon and silica

The implantation formation of InAs nanoclusters in silicon and silica and their modification via irradiation with Xe ions with an energy of 167 MeV and a fluence of 3 × 10¹⁴ cm^–2 are studied. It is found that post-implantation annealing and irradiation with high-energy ions alter the size and shape of nanoclusters and cause structural transformations within them. The ordering of nanoclusters and their elongation along the trajectory of Xe ions in a SiO₂ matrix is observed.