In-beam M?ssbauer spectroscopy of 57 Mn implanted into lithium hydride

We measured the temperature dependence of ⁵⁷Fe M?ssbauer spectra obtained after ⁵⁷Mn implantation into polycrystalline LiH with an extremely low implantation dose. Density functional calculations suggested that the Fe atoms were predominantly implanted into both Li and H substitutional sites of the LiH crystal.     

Phase analysis in α-Fe after high-dose Si ion implantation by depth-selective conversion-electron Mössbauer spectroscopy (DCEMS)

Si⁺ ions of 50 keV in energy were implanted into α-Fe (95% ⁵⁷Fe) with a nominal dose of 5 × 10¹⁷ cm^?2 at 350°C. The depth distribution of the Fe-Si phases formed by ion implantation after annealing at 300 and 400°C for 1 h was studied quantitatively by depth-selective conversion-electron Mössbauer spectroscopy (DCEMS). Ordered Fe₃Si and ε-FeSi was observed.     

Influence of Cr<Superscript>+</Superscript> ion implantation and pulsed ion-beam annealing on the formation and optical properties of Si/CrSi<Subscript>2</Subscript>/Si(111) heterostructures

The effect of pulsed ion-beam annealing on the surface morphology, structure, and composition of single-crystal Si(111) wafers implanted by chromium ions with a dose varying from 6 × 10¹⁵ to 6 × 10¹⁶ cm⁻² and on subsequent growth of silicon is investigated for the first time. It is found that pulsed ion-beam annealing causes chromium atom redistribution in the surface layer of the silicon and precipitation of the polycrystalline chromium disilicide (CrSi₂) phase. It is shown that the ultrahigh-vacuum cleaning of the silicon wafers at 850°C upon implantation and pulsed ion-beam annealing provides an atomically clean surface with a developed relief. The growth of silicon by molecular beam epitaxy generates oriented 3D silicon islands, which coalesce at a layer thickness of 100 nm and an implantation dose of 10¹⁶ cm⁻². At higher implantation doses, the silicon layer grows polycrystalline. As follows from Raman scattering data and optical reflectance spectroscopy data, semiconducting CrSi₂ precipitates arise inside the silicon substrate, which diffuse toward its surface during growth.     

Phase analysis of a nitrogen implanted CrNi 18.9 steel: A cems-study

Conversion Electron Mössbauer Spectroscopy (CEMS) has been used to study the modified structure of the near surface region of a nitrogen implanted austenitic X10CrNiTi18.9 steel. The implantation dose was varied from 2 to 8*10¹⁷N⁺/cm² using an implantation temperature of 200°C and an ion energy of 100 keV. The (γ/a′)-ratio in the near surface region of the untreated material was changed by electropolishing and mechanical polishing of the surface. The results of the spectra are discussed in terms of nitrogen solid solution in the case of low nitrogen doses and precipitation of Fe-nitrides (ε-Fe₂N, ε-Fe_2+xN) with increasing implantation dose. Phase transformations referring to the Fe-nitrides and the (γ/a′)-ratio are observed with increasing nitrogen content.     

Energetic Sn+ irradiation effects on ruthenium mirror specular reflectivity at 13.5-nm

Sn⁺ irradiations of Ru single-layer mirrors (SLM) simulate conditions of fast-Sn ion exposure in high-intensity 13.5 nm lithography lamps. Ultra-shallow implantation of Sn is measured down to 1–1.5 nm depth for energies between 1–1.3 keV at near-normal incident angles on Ru mirror surfaces. The Sn surface concentration reaches an equilibrium of 55–58% Sn/Ru for near-normal incidence and 36–38% for grazing incidence at approximately 63 degrees with respect to the mirror surface normal. The relative reflectivity at 13.5 nm at 15-degree incidence was measured in-situ during Sn⁺ irradiation. For near-normal Sn⁺ exposures the reflectivity is measured to decrease between 4–7% for a total Sn fluence of 10¹⁶ cm⁻². Theoretical Fresnel reflectivity modeling shows for the same fluence assuming all Sn atoms form a layer on the Ru mirror surface, that the reflectivity loss should be between 15–18% for this dose. Ex-situ absolute 13.5 nm reflectivity data corroborate these results, indicating that implanted energetic Sn atoms mixed with Ru reflect 13.5-nm light differently than theoretically predicted by Fresnel reflectivity models.     

Microstructure and thermal stability of Fe,Ti, and Ag implanted yttria-stabilized zirconia

Yttria-stabilized zirconia (YSZ) was implanted with 15 keV Fe or Ti ions up to a dose of 8×10¹⁶ at cm^–2. The resulting dopant concentrations exceeded the concentrations corresponding to the equilibrium solid solubility of Fe₂O₃ or TiO₂ in YSZ. During oxidation in air at 400° C, the Fe and Ti concentration in the outermost surface layer increased even further until a surface layer was formed of mainly Fe₂O₃ and TiO₂, as shown by XPS and ISS measurements. From the time dependence of the Fe and Ti depth profiles during anneal treatments, diffusion coefficients were calculated. From those values it was estimated that the maximum temperature at which the Fe- and Ti-implanted layers can be operated without changes in the dopant concentration profiles was 700 and 800° C, respectively. The high-dose implanted layer was completely amorphous even after annealing up to 1100° C, as shown by scanning transmission electron microscopy. Preliminary measurements on 50 keV Ag implanted YSZ indicate that in this case the amorphous layer recrystallizes into fine grained cubic YSZ at a temperature of about 1000° C. The average grain diameter was estimated at 20 nm, whereas the original grain size of YSZ before implantation was 400 nm. This result implies that the grain size in the surface of a ceramic material can be decreased by ion beam amorphisation and subsequent recrystallisation at elevated temperatures.     

The electrical behaviour of abrupt ion implanted and diffused P+N junctions

Abstract

Results are reported of measurements of the properties of diodes formed by ion implantation, and for comparison boron diffused P⁺N diodes of similar area close by on the same chip. The four group III acceptor impurities were implanted separately to a dose of 5 × 10¹⁵ ions/cm² at room temperature into similar samples of suitably masked silicon. Boron ions were also implanted at liquid nitrogen temperature and 450°C. Annealing was limited to a maximum temperatare of 550 °C.

Measurements have been made of sheet resistance, forward and reverse I-V characteristics (from 10^?9 amps/cm²), reverse breakdown voltage, noise, minority carrier storage time and junction series resistance.

The bulk properties of boron implanted diodes were found to be reproducible. The introduction of recombination centres by implantation is the major factor influencing variation in these properties between one implantation condition and another. Changes in surface oxide conditions probably affect reverse leakage currents and breakdown voltages.

The properties of boron implanted diodes are considered suitable for applications such as the MOSFET, and are superior to those of the AI, Ga and In implanted diodes.     

Room temperature magnetic properties of Fe and C implanted ZnO films

ZnO films prepared by radio frequency magnetron sputtering were singly or sequentially implanted with 120 keV Fe ions at a fluence of 5 × 10¹⁶ ions/cm² and 20 keV C ions at a fluence of 3 × 10¹⁵ ions/cm². Magnetic and optical properties as well as structures of the films have been investigated using various techniques. Magnetic measurements show that the as-deposited ZnO film presents room temperature ferromagnetism. Single Fe or C ion implantation has no contribution to enhancement in the film magnetism, while magnetic moment increases distinctly in the Fe and C ions sequentially implanted film. Results from structural measurements reveal that Fe nanoparticles are formed in the Fe singly implanted ZnO film. The post C implantation induces dissolution of Fe nanoparticles and promotes Fe atoms to substitute Zn atoms in the lattice. Based on the structural results, the effect of magnetic enhancement has been tentatively interpreted.     

Defect annealing in Sb/Sn implanted diamond investigated with Sn Mössbauer spectroscopy

The annealing of defects in Sb/Sn implanted diamond has been studied in ¹¹⁹Sn Mössbauer spectroscopy following the implantation of radioactive parent isotopes ¹¹⁹Xe and ^119mSn. Our results show that after annealing above 1300 K, 40% of the implanted ions are located at or near regular sites in the lattice. Significant implantation induced defects however remain.     

Effect of implantation temperature on the blistering behavior of hydrogen implanted GaN

GaN epitaxial layers were implanted by 100 keV H⁺ ions at different implantation temperatures (LN₂, RT and 300 °C) with a fluence of 2.5×10¹⁷ cm^?2. The implanted samples were characterized using Nomarski optical microscopy, AFM, XRD, and TEM. Topographical investigations of the implanted surface revealed the formation of surface blistering in the as-implanted samples at 300 °C and after annealing at higher temperature for the implantation at LN₂ and RT. The physical dimensions of the surface blisters/craters were dependent on the implantation temperature. XRD showed the dependence of damage-induced stress on the implantation temperature with higher stress for the implantation at 300 °C. TEM investigations revealed the formation of a damage band in all the cases. The damage band was filled with large area microcracks for the implantation at 300 °C, which were responsible for the as-implanted surface blistering.     

Impurity lattice sites after implantation of Te and Sb in GaAs: Search for the DX centre

¹¹⁹Sn Mössbauer Spectroscopy has been applied to study the nearest environment of radioactive^119mTe and¹¹⁹Sb atoms implanted into GaAs. After a low-dose implantation and annealing above 300°C the impurity atoms are found at As sites. High-dose implantation and annealing above 600°C results in the population of at least two additional sites; these are clearly different for Te and Sb. No evidence is found for the population of DX-centres. A likely possibility is the formation of coherent Ga₂Te₃ precipitates.     

High dose implantation of Eu into α-Fe

Abstract

At the UNILAC injector at GSI ¹⁵¹Eu was implanted into an α-Fe foil [8]. According to our simulation code of the energy loss of the implanted ions an energy of 1.5 MeV was chosen to minimize the sputter yield during implantation and to produce the highest possible Eu concentration near the surface of the sample. After the irradiation with a dose of 3.6 · 10¹⁷ Eu/cm² the implantation profile should reach its maximum of 8 at. % Eu at the surface of the sample and its width should be 1700 Å.     

Magnetic Properties of Thin Metal-Polymer Films Prepared by High-Dose Ion-Beam Implantation of Iron and Cobalt Ions into Polyethylene Terephthalate

Thin metal-polymer composite films have been prepared by high-dose ion-beam implantation of Fe⁺ and Co⁺ ions into polyethylene terephthalate. The implantation of 40 keV ions at room temperature with doses from 2 · 10¹⁶ to 4 · 10¹⁷ cm⁻² have been performed, with the ion current density of 4 μA/cm². The effects of implantation dose on the film morphology and crystal structure have been investigated via atomic force and magnetic force microscopy and X-ray diffraction. The magnetic properties of synthesized structures have been studied by ferromagnetic resonance and with a vibrating-sample magnetometer. It was established that the properties of ion-implanted samples strongly depend on both the implantation dose and the type of implanted ions. The implantation dose at which the magnetic phase is formed for iron-implanted samples is significantly lower than that for cobalt-implanted ones. At high implantation doses due to polymer sputtering metal-containing layers are formed close to the sample surface for both ions. In this dose range the magnetic properties of implanted samples changed dramatically due to particle oxidation. The coercivity of synthesized layers reaches 180 and 300 Oe for iron- and cobalt-implanted samples, respectively. Authors' address: Vladimir Yu. Petukhov, Kazan Physical-Technical Institute, Sibirskii trakt 10/7, 420029 Kazan, Russian Federation     

57Fe conversion electron Mössbauer spectrometric study of boron and carbon ion implanted irons

Amorphous layers produced at the surface of iron by B⁺ and C⁺ implantation (50 kV, 1×10¹⁸ ions cm⁻²) were analyzed by CEMS. The CEM spectrum of B⁺ implanted layer was composed of broad doublet and sextet. Spread hyperfine field distribution, P(H), indicates the formation of extremely disordered FeB layer. Annealing at 400°C brought about precipitation of FeB, which was converted to Fe₂B by annealing at 500°C. The P(H) for C⁺ implanted iron was resolved to 3 subpeaks with H values of 11.0, 18.0 and 22.5 T. The amorphous FeC phase was strongly correlated to crystalline Fe₅C₂ and Fe₂C, which precipitated at 300°C and were transformed into Fe₃C at 500°C. The amorphous layer disappeared by annealing at 600°C.     

Structure and micro-mechanical properties of helium-implanted layer on Ti by plasma-based ion implantation

The present paper concentrates on structure and micro-mechanical properties of the helium-implanted layer on titanium treated by plasma-based ion implantation with a pulsed voltage of −30 kV and doses of 3, 6, 9 and 12 × 10¹⁷ ions/cm², respectively. X-ray photoelectron spectroscopy and transmission electron microscopy are employed to characterize the structure of the implanted layer. The hardnesses at different depths of the layer were measured by nano-indentation. We found that helium ion implantation into titanium leads to the formation of bubbles with a diameter from a few to more than 10 nm and the bubble size increases with the increase of dose. The primary existing form of Ti is amorphous in the implanted layer. Helium implantation also enhances the ingress of O, C and N and stimulates the formations of TiO₂, Ti₂O₃, TiO, TiC and TiN in the near surface layer. And the amount of the ingressed oxygen is obviously higher than those of nitrogen and carbon due to its higher activity. At the near surface layer, the hardnesses of all implanted samples increases remarkably comparing with untreated one and the maximum hardness has an increase by a factor of up to 3.7. For the samples implanted with higher doses of 6, 9 and 12 × 10¹⁷ He/cm², the local displacement bursts are clearly found in the load-displacement curves. For the samples implanted with a lower dose of 3 × 10¹⁷ He/cm², there is no obvious displacement burst found. Furthermore, the burst width increases with the increase of the dose.     

Surface damage and topography of erbium metal films implanted with helium to high fluences

Topographical and expansion effects which occur as a result of implanting erbium thin films with helium up to fluences of 1.5 × 10¹⁸ He⁺/cm² are described. There exists an inverse relationship between critical dose and annealing temperature with respect to the formation of surface bubbles. Post implantation annealing at or below 400°C is found to strongly reduce implantation induced expansion for doses less than 3.5 × 10¹⁷ He⁺/cm², but is observed to result in increased expansion above this dose. At temperatures above 400°C, expansion is increased for all doses investigated. Details of bubble development in the implanted layer are discussed and the manner in which surface bubbles develop from enlarged subsurface bubbles is illustrated.     

Structural phenomena in glassy carbon induced by cobalt ion implantation

Glassy carbon (GC) was implanted by 150 keV Co⁺ ions to the doses of 1×10¹⁶ (low dose) and 1×10¹⁷ ions/cm² (high dose). The low dose implantation results in GC structure disordering with formation of amorphous carbon (a-C). Analysis of Rutherford backscattering (RBS) and Raman spectra has revealed 15 at.% of sp³-bonded C atoms in the a-C structure. The in-pane size of sp² clusters was estimated to be 1.1 nm. On the contrary, the high dose ion implantation results in ordering of the a-C structure. Content of the sp³ atoms in a-C was reduced to about 5% and, respectively, the in-plane sp² cluster size was increased up to 2.8 nm. Together with the a-C structure ordering the Raman spectra identifies formation of transpolyacetylene (TPA)-like chains after the high-dose Co⁺ implantation. In parallel, RBS suggests an enhanced diffusion of the implanted cobalt within the modified carbon layer. Correlation of the RBS and Raman results argues a driving role of cobalt diffusion in the TPA-like chains formation and a-C ordering. Great surface roughening observed after the high dose Co⁺ implantation suggests also the pronounced cobalt clustering causing large flux of “free volume” to the surface.     

Channeling study of boron implanted silicon: Liquid nitrogen temperature implantation

Silicon samples have been boron implanted at 150 keV at liquid nitrogen temperature to a dose of 3.6 × 10¹⁵/cm². This dose rendered the implanted layer amorphous as viewed by helium ion backscattering. Four kinds of room temperature measurements were made on the same set of samples as a function of the isochronal annealing temperature. The measurements made were the determination of the substitutional boron content by the channeling technique using the B¹¹(p, α) nuclear reaction, observation of the disorder by helium ion backscattering, determination of the carrier concentration by van der Pauw Hall measurements, and the sheet resistivity by four point probe measurements. These measurements are compared with results from samples implanted at room temperature. The carrier concentration correlates well with the substitutional boron content for both room temperature and liquid nitrogen temperature implantations. Following annealing temperatures in the 600 to 800°C range, a much larger percentage of the boron lies on substitutional lattice sites, and therefore the carrier concentration is larger, if the implantation is done at liquid nitrogen temperature rather than at room temperature. Following liquid nitrogen temperature implantation, reverse annealing is observed from 600 to 800°C in the substitutional boron content, carrier concentration and sheet resistivity. The boron is more than 90 per cent substitutional after annealing to 1100°C for both the room temperature and liquid nitrogen temperature implantations. The low temperature implantation produced a buried amorphous layer, and this layer was observed to regrow from both the surface and substrate sides at approximately equal rates.     

Structural and phase transformations in Ni3Fe during high-dose ion implantation

The results are given for experimental studies of the structural-phase state formed in the surface and nearsurface layers of a disordered polycrystalline Ni₃Fe alloy during high-dose ion implantation. The studies used Auger electron spectroscopy, transmission electron microscopy, x-ray structural analysis, and microhardness measurements. The ion implantation was done using the “Raduga” vacuum arc source with a multicomponent cathode of composition Zr (89.5 wt. %)+C+N+O with an acceleration voltage of 50 kV. The implanted ion dose was varied in the range (6.0·10¹⁶–6.0·10¹⁷) ions/cm². It was established that in the surface layer which is alloyed during ion implantation there is amorphization with simulataneous formation of finely dispersed ZrO₂ particles whose dimensions increase with increasing implanted ion dose; this is accompanied by an increased internal mechanical stress. Beyond the ion-implanted layer a sublayer about 10 μm thick with a high dislocation density is formed (the “long-range action” effect). The results of microhardness measurements correlate with the data from structural studies. Institute of the Physics of Strength and Materials Science, Siberian Section, Russian Academy of Science; Tomsk State University—Architectural-Construction University; and Scientific Research Institute for Nuclear Physics at Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 15–24, November, 1998.     

Alloying by high dose ion implantation of iron into magnesium and aluminium

Alloys of the systems Fe–Al (mixable over the whole concentration range) and Fe–Mg (insoluble with each other) were produced by implantation of Fe ions into Al and Mg, respectively. The implantation energy was 200 keV and the ion doses ranged from 1 × 10₁₄ to 9 × 10₁₇cm^-2The obtained implantation profiles were determined by Auger electron spectroscopy depth profiling. Maximum iron concentrations reached were up to 60 at.% for implantation into Al and 94 at.% for implantation into Mg. Phase analysis of the implanted layers was performed by conversion electron Mössbauer spectroscopy and X‐ray diffraction. For implantation into Mg, two different kinds of Mössbauer spectra were obtained: at low doses paramagnetic doublets indicating at least two different iron sites and at high doses a dominant ferromagnetic six‐line‐pattern with a small paramagnetic fraction. The X‐ray diffraction pattern concluded that in the latter case a dilated αiron lattice is formed. For implantation into Al, the Mössbauer spectra were doublet structures very similar to those obtained at amorphous Fe–Al alloys produced by rapid quenching methods. They also indicated at least two different main iron environments. For the highest implanted sample a ferromagnetic six‐line‐pattern with magnetic field values close to those of Fe₃Al appeared.