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The lattice location of ion implanted radioactive 24Na (t1/2=14.96 h) in GaN and AlN was determined using the emission channeling technique at the ISOLDE/CERN facility. In the room temperature as-implanted state in both GaN and AlN, the majority of the sodium atoms are found on interstitial sites near the octahedral position, with a minority on cation Ga or Al substitutional sites. Following annealing at 800-900°C the interstitial fraction is reduced while the substitutional incorporation increases. Our results thus further establish the amphoteric character of Na in GaN and AlN, in analogy to the other light alkali Li, and alkaline earths Be and Mg. The site changes upon annealing are attributed to the onset of migration of interstitial Na, for which an activation energy of 2.2-3.4 eV is estimated in GaN and 2.0-3.1 eV in AlN, and its subsequent capture by cation vacancies resulting from the implan-tation. Comparison of the lattice site change behavior of Li, Be, Na and Mg shows that the onset of interstitial mi-gration correlates with the ionic radii of these elements.

Pronounced room temperature vertical shifts in the magnetic hysteresis loops of granular, highly polycrystalline and ferromagnetic-like BiFeO3 thin films are observed upon field-cooling from a temperature above the Neel temperature of bulk BiFeO3. This is ascribed to the interplay between the preferential alignment, established by the field-cooling process, of the net magnetic moment, which arises from uncompensated antiferromagnetic spins, and the pinning of a fraction of these spins at the particle boundaries. Conversely, field-cooling of an epitaxially grown BiFeO3 film results in no vertical shift, confirming the effective role played by the particle boundaries (i.e., morphology) of the granular-like BiFeO3 films in the process of spin frustration.

59Co nuclear magnetic resonance has been used to study the formation of Co nanoclusters in several series of thin-film Ag1−xCox alloys (0.08⩽x⩽0.4) prepared by coevaporation and subjected to different heat treatments. Co particles originally formed during the deposition process were found to be single-domain fcc Co clusters, having the shape of truncated octahedra of about 4.5 nm in diameter. Annealing at 200 °C resulted in a size increase to about 7 nm, but after annealing at 350 °C, the particles grew to about 26 nm while remaining single magnetic domain. Upon further annealing, the onset of large, multidomain Co clusters is evidenced. The Co concentration in the original alloy influenced the density of Co particles, but not their size, which was essentially determined by the annealing conditions.

Thin films of e-FeSi were grown by deposition of Fe on a Si〈111〉 substrate under ultrahigh vacuum conditions, followed by in situ annealing at 450 °C. These e-FeSi films were subjected to irradiation from a pulsed excimer laser in the energy density range 0.30–0.90 J/cm2, in order to study the phase formation and crystallization processes of metastable [CsCl]Fe1−xSi phases. The samples were analyzed by Rutherford backscattering and channeling spectrometry and by cross-sectional transmission electron microscopy. Considerable diffusion of silicon into the silicide film was found to occur during the pulsed laser annealing, resulting in a film with nonstochiometric composition. In contrast to solid phase reaction, epitaxial ordering in the iron silicide film is observed during pulsed laser annealing when the film’s composition approaches that of FeSi2. Analysis by cross-sectional transmission electron microscopy confirmed that the phase which exhibits epitaxial ordering corresponds to the metastable [CsCl]Fe1...

In atomic layer deposition (ALD), film thickness control by counting the number of deposition sequences is poor in the initial, nonlinear growth region. We studied the growth of TiN films formed by sequentially controlled reaction of TiCl4 and NH3 on thermal SiO2 during the transient, nonlinear period. Using low-energy ion scattering and Rutherford backscattering spectroscopy analysis, we have found that a three-dimensional growth of islands characterizes the ALD TiN growth on SiO2. Growth at different temperatures (350 °C and 400 °C) affects the extent of the transient region and the rapid closure of the film. At 400 °C, a reduced growth inhibition and an earlier start of three-dimensional growth of islands results in film closure at about 100 cycles, corresponding to a TiN thickness of 24±3 A. At 350 °C the minimum thickness at which the TiN layer becomes continuous is 34±3 A, deposited with 150 cycles.

Co1−xFexSi2 and Ni1−xFexSi2 metastable ternary phases were formed by sequentially implanting Co, Ni, and Fe into Si (111) at 623 K. In order to compare the phases formed by ion implantation, the Ni1−xFexSi2 stable bulk ternary phase with a wide variety of x values was synthesized. The samples were studied by Mossbauer effect, transmission electron microscopy (TEM), x-ray diffraction, and Rutherford backscattering and channeling. X-ray diffraction and TEM results on the as-implanted samples with x=0.5 indicate a cubic (fluorite) structure. 57Fe Mossbauer spectra show three resonanceline components. Comparison of the isomer shift values of the components with those measured in the stable and metastable transition-metal silicide phases indicated three different sites for iron atoms: Fe substituting Co or Ni; Fe in the empty cubes of the fluorite-type lattices; and Fe populating sites in the CsCl-type B2 lattice. In samples of Ni1−xFexSi2 annealed at 1273 K, α-FeSi2 and a fraction of Fe dissolved in NiSi2 app...

Epitaxial GdSi1.7 layers have been produced by channeled ion beam synthesis. The crystalline quality improves with implant dose and substrate temperature. The latter determines the extent of dynamic annealing whereas both factors are instrumental in driving precipitate growth. This, in turn, promotes the formation of a continuous silicide layer following annealing. The information obtained in this study allows the production of high quality layers with a room temperature resistivity of 86 μΩ cm. Evidence of magnetic ordering is apparent below 44 K.

We describe an experimental setup for conversion electron Mossbauer spectroscopy (CEMS) at low temperature. The setup is composed of a continuous flow cryostat (temperature range of 4.2-500 K), detector housing, three channel electron multipliers, and corresponding electronics. We demonstrate the capabilities of the setup with CEMS measurements performed on a sample consisting of a thin enriched 57Fe film, with a thickness of 20 nm, deposited on a silicon substrate. We also describe exchangeable adaptations (lid and sample holder) which extend the applicability of the setup to emission Mossbauer spectroscopy as well as measurements under an applied magnetic field.

yield (;30%) is as low as that of state-of-the-art bulk material, and the interface is atomically abrupt. The initial film deposits are epitaxial islands, and subsequent growth is in the Frank‐van der Merwe mode. With the islands already relaxed at the nucleation stage and coalescing to essentially uniform coverage with the first monolayer of deposition, GaSe on Si~111! provides an example of van der Waals epitaxy. However, it is difficult to understand how epitaxy ~crystallographic alignment with the substrate! can occur in such a case, where the film is incommensurate starting from the initial nuclei. A mechanism for alignment of the islands is proposed: they are aligned with the silicon substrate through the influence of dangling bonds at their perimeter, being ‘‘quasicommensurate ’’ by virtue of their small lateral size. Although discommensurate regions are created as the islands grow laterally, there is simply no change in their orientation. © 1997 American Institute of Physics. @S0021-8979~97!05011-1# The hexagonal, layered semiconductor, GaSe, has been shown to grow on Si~111! by molecular beam epitaxy ~MBE! in a remarkable way: the film is crystallographically aligned with the substrate ~and remains so after the accumulation of 1 mm! and this epitaxy occurs in spite of the fact that, starting from sub-monolayer coverage, the film is misfitting and relaxed. 1

A continuous buried GdSi1.7 layer is formed by channelled implantation of 90 keV Gd ions into Si(111). In the case of (001) oriented silicon substrates, the silicide film is formed on the silicon surface. Its worse crystalline quality is due to the epitaxy occurring relative to all four {111}Si planes resulting in a textured GdSi1.7 layer. Annealing at a temperature of ⩾850 °C for 30 min results in the presence of only the orthorhombic GdSi2 phase on the silicon surface for both (111) and (001) silicon substrates. However, the precipitates embedded in the silicon substrate are still hexagonal GdSi1.7. The phase transformation temperature is higher for (111) than for (001) silicon.

ErSi1.7 layers with high crystalline quality (χmin of Er is 1.5%) have been formed by 90 keV Er ion implantation to a dose of 1.6×1017/cm2 at 450 °C using channeled implantation. The perpendicular and parallel elastic strain e⊥=−0.94%±0.02% and e∥=1.24%±0.08% of the heteroepitaxial erbium silicide layers have been measured with symmetric and asymmetric x‐ray reflections using a double‐crystal x‐ray diffractometer. The deduced tetragonal distortion eT(XRD)=e∥−e⊥ =2.18%±0.10%, which is consistent with the value eT(RBS)=2.14±0.17% deduced from the Rutherford backscattering and channeling measurements. The quasipseudomorphic growth of the epilayer and the stiffness along a and c axes of the epilayer deduced from the x‐ray diffraction are discussed.

Heteroepitaxial ErSi1.7 layers with excellent crystallinity (χmin of Er is 1.5%) have been prepared by high‐dose 90 keV Er implantation into a Si(111) substrate using channeled implantation. Such an ErSi1.7/Si system offers a rare opportunity to study comprehensively the structure, orientation, and strain using Rutherford backscattering spectrometry and channeling analysis. We found that the minimum yield and width of the [0001] dip of the Er atoms are quite different from that of the Si atoms in the silicide layer. It is confirmed that the azimuthal orientation of the hexagonal ErSi1.7 layer to the cubic Si substrate is ErSi1.7 [0001] ∥ Si[111] and ErSi1.7 {1120} ∥ Si {110}, and that the epilayer is compressively strained. Besides, by using the angular scan and image scan, we reveal that the dips of the {1010} family are missing for the Si atoms in the epilayer but do exist for the Er atoms in the same epilayer. The reason for this drastic difference is explained by the separate {1010} planes and the different steering potential of the Si and Er atoms in ErSi1.7.

Room temperature magnetoelectric BiFeO3-BaTiO3 superlattices with strong out-of-plane magnetic anisotropy have been prepared by pulsed laser deposition. We show that the out-of-plane magnetization component increases with the increasing number of double layers. Moreover, the magnetoelectric voltage coefficient can be tuned by varying the number of interfaces, reaching a maximum value of 29 V/cm Oe for the 20×BiFeO3-BaTiO3 superlattice. This enhancement is accompanied by a high degree of perpendicular magnetic anisotropy, making the latter an ideal candidate for the next generation of data storage devices.

We have investigated structural and electrical properties of defects introduced during room temperature europium implantation into GaN. Two geometries, random and channeled implantation, were used. Rutherford backscattering and channeling analysis reveals that implantation induces a significantly lower concentration of defects, in the case of channeled implantation. These defects generate a perpendicular expansion of the GaN lattice in the implanted region, as evidenced by x-ray diffraction. From deep-level transient spectroscopy, beside intrinsic defects with energy levels below the conduction band, one additional electron trap, labeled Eu2, is observed at an energy (Ec−0.36eV). It is believed that this defect in n‐GaN is europium related.

Epitaxially stabilized iron monosilicide films with the CsCl structure (B2-FeSi) have been investigated by conversion electron Mossbauer spectroscopy and x-ray diffraction. A detailed investigation of the elastic strain in these metastable layers is presented. Using hyperfine interaction information the tetragonal distortion of the silicide lattice could be quantified for layers as thin as 14A. A general tendency for strain relaxation with increasing layer thickness is observed.

We have investigated the role of the substrate in the growth mechanism of TiN films grown by atomic layer deposition. The early stage of the film formation is dominated by a Volmer–Weber-type growth mode, driven by the ligand exchange of reactant molecules with preferential surface function groups. The density of function groups on the initial surface dictates the density and the vertical dimension of TiN islands, the evolution of the substrate coverage, and the minimum thickness at which the films become continuous.

© 2016 Author(s). The effect of thermal annealing on epitaxial GeSn (6.5% Sn) strained layers grown on Ge-buffered Si(100) wafers has been investigated using Rutherford backscattering spectrometry and X-ray diffraction to unambiguously determine the Sn substitutional content as well as the elastic strain in the layers. Vacuum annealing at temperatures below 400 °C for 20 min has no noticeable effect on the strain in the epitaxial layers. Once the temperature was raised above 400 °C, however, relaxation of the layer sets in and the GeSn layer has essentially completely relaxed following a 20 min anneal at 650 °C. Using Rutherford backscattering and channelling spectrometry to provide compositional information as a function of depth enables one to monitor the effect of the thermal anneal on the Sn distribution throughout the layer, and also to directly extract their substitutional fraction (i.e., their solubility in the lattice). The results obtained show that when the relaxation initially sets in both the Ge and the Sn remain firmly bound in substitutional lattice sites and it is only around 600 °C, and after substantial relaxation has taken place, that Sn is finally expelled from lattice sites and diffuses to the surface of the sample. ispartof: Journal of Applied Physics vol:120 issue:14 pages:1-7 status: published

NiSi2(111) and NiSi2(100) layers with good crystalline quality have been formed by ion‐beam synthesis. An unusual Ni atom distribution showing two completely separated layers during a single implantation step has been observed by Rutherford backscattering spectrometry (RBS) and transmission electron microscopy (TEM). The orientation, strain, and stiffness of the NiSi2 layers have been studied by RBS/channeling, x‐ray diffraction, and TEM. The results show that the continuous NiSi2 layers have type‐A orientation with a parallel elastic strain larger than the theoretical value of 0.46% for pseudomorphic growth. The perpendicular strain of the NiSi2(111) layers is apparently smaller than that of NiSi2(100) layers, indicating a higher stiffness in the 〈111〉 direction.

Vacuum evaporation techniques were applied to the epitaxial growth of CrSi2 on Si(111) substrates. There are two CrSi2 matching faces which offer good lattice matchings, and which are observed experimentally: the (001) and the (111). These are present together in films grown by reactive deposition at temperatures from 450 to 1000 °C, with the latter matching face becoming more dominant as the growth temperature is raised. During an anneal at 1100 °C, however, the regions of the (111) matching face disappear in films ≥∼84 A thick. Moderately good epitaxial alignment is obtained with the other matching face operative. Films ≤∼30 A thick yield an opposite result: they adopt exclusively the (111) matching face as a result of this anneal. For both heteroepitaxial relationships, a strong islanding tendency is manifested during growth (unless the CrSi2 layer is more than a few thousands of angstroms thick), which is accentuated by such a post‐growth anneal. The population of CrSi2 islands exhibits a gradual stra...

Damage and strain produced in a 370‐nm‐thick strained epitaxial Ge0.10Si0.90 film on Si(100) by irradiation with 320 keV 28Si+ ions at fixed temperatures ranging from 40 to 150 °C and for doses from 1 to 30×1014/cm2 have been measured by MeV 4He channeling spectrometry, transmission electron microscopy, and high‐resolution x‐ray diffractometry. The ion energy was chosen so that the maximum damage created by irradiation occurs very near the GeSi‐Si interface. For all temperatures, the retained damage and the perpendicular strain induced by the irradiation are significantly greater in the GeSi epilayer than in the Si substrate. For all doses the retained damage and the induced perpendicular strain become small above 100 °C. Both rise nonlinearly with increasing ion dose. They are related to each other differently in GeSi than in bulk Si or Ge irradiated at room temperature. Postirradiation furnace annealing can remove a large portion of the induced damage and strain for nonamorphized samples. Amorphized sam...

Reactive deposition epitaxy was used to synthesize thin layers of RexMo1−xSi2 on Si(100). In the case of x=1, ReSi2 layers of excellent crystalline quality have been reported previously [J. E. Mahan, K. M. Geib, G. Y. Robinson, R. G. Long, Y. Xinghua, G. Bai, and M.‐A. Nicolet, Appl. Phys. Lett. 56, 2439 (1990)]. In the case of x=0, however, virtually no alignment of the MoSi2 and the substrate is found, although this silicide is nearly isomorphic to ReSi2. For intermediate values of x, highly epitaxial ternary silicides are obtained, at least for a Mo fraction up to 1/3.

The inversion of a bilayer of Co on top of Ti and a Si(100) substrate upon steady‐state annealing, and the resultant formation of an epitaxial CoSi2 layer have been studied using both reactive (N2, N2+5% H2, He+14% H2) and nonreactive (vacuum) annealing ambients. In nitrogen, a high‐quality, single‐crystalline CoSi2 layer forms above 600 °C for 30 min, with an abrupt interface to the substrate. As the fraction of hydrogen in the ambient increases, the abruptness of the interface deteriorates slightly. On top of this silicide, the Ti is chemically bound with oxygen present as a contaminant. In the case of a nonreactive annealing ambient, the Co/Ti inversion still takes place, although it is only partial. Moreover, the interface is very rough. The structure is unstable above 800 °C for 30 min annealing and transforms into a mixed layer of Co0.25Ti0.75Si2 and epitaxial CoSi2 grains. Using isothermal vacuum annealings with varying durations, a square‐root time dependence is observed for the growth of the epit...

Channeled implantation of 80 keV Er ions into Si(111) has been investigated as a function of the angle between the ion beam and the 〈111〉 normal axis. The angular dependence of both the projected range and the crystalline quality of the resulting silicide shows excellent agreement with theoretical predictions and simulations. Simulations indicate that the critical angle for channeling is largely independent of substrate temperature. The postimplantation strain in the silicide layer is determined by irradiation-induced damage and therefore increases with the angle between the crystalline axis and the ion beam direction.

Rutherford backscattering and channeling have been used to characterize the structure of a GaN layer grown on a Si(111) substrate. The results show that a 1.26 mum GaN epitaxial layer with a rather abrupt interface and a good crystalline quality (chi(min)=3.4%) can be grown on a Si(111) substrate. Using the channeling angular scan around an off-normal axis in the {10 (1) over bar0} plane of the GaN layer, the tetragonal distortion e(T), which is caused by the elastic strain in the epilayer, can be determined. Moreover, the depth dependence of the e(T) can be obtained using this technique. A fully relaxed (e(T)=0) GaN layer for a thickness

The lattice location of iron in thin-film, single-crystalline hexagonal GaN was studied by means of the emission channeling technique. Following 60-keV room-temperature implantation of the precursor isotope $^{59}$Mn at a dose of 1.0 $\times 10^{13}$ cm$^{-2}$ and annealing up to 900°C, the angular distribution of $\beta^{-}$-particles emitted by the radioactive isotope $^{59}$Fe was measured by a position-sensitive electron detector. The $\beta^{-}$-emission patterns around the [0001], [1102], [1101] and [2113] directions give direct evidence that the majority of Fe (80%) occupies substitutional Ga sites.

We report a direct observation of quantum dots formed spontaneously in a thick InGaN epilayer by high resolution transmission electron microscopy. Investigation of a (280 nm thick) In0.22Ga0.78N single layer, emitting in the blue/green spectral region, reveals quantum dots with estimated sizes in the range of 1.5-3 nm. Such sizes are in very good agreement with calculations based on the luminescence spectra of this specimen. (C) 2000 American Institute of Physics. [S0003-6951(00)00930-X].

By implanting Co and Fe in sequence into Si (111), metastable ternary Co1−xFexSi2 phases were formed. Mossbauer effect measurements showed three resonance line components in the spectrum. Comparison of the central shift (CS) values of the components with those appearing in the stable ternary phases indicated that iron atoms are positioned in the substitutional Co site, in the empty cube of the fluorite-type lattice and in CsCl-like B2 structures. It was found that the CS values of two components are in the velocity range of the values obtained for the metastable γ-FeSi2 synthesized using various methods. This result suggests the existence of a similar structure.

A possibility for decorating atomic steps on single-crystal surfaces by using ultralow energy ion beams is reported. Isotopically pure ion beams are produced by a mass separator and subsequently decelerated by an electrostatic lens. The lens was designed to allow sweeping of the ion beam in order to obtain a uniform deposition over a large area. The preferred sites of single Co atoms on Ag are investigated with in situ scanning tunneling microscopy measurements. A clear indication is found that by increasing the energy of the deposited Co to several electron volts, an enhanced Co decoration of the Ag steps is induced. This technology opens perspectives for an increasing number of elements which can form self-organized nanostructures such as atomic wires on vicinal crystal surfaces.

Slow (low-rate) reactive deposition of a metal onto a Si substrate can result in direct formation of a metal disilicide, thereby skipping the metal-rich phases in the formation sequence. These observations have been explained thermodynamically by using the effective heat of formation model. As a result of this concentration-controlled phase selection, it is possible to form disilicides, such as CoSi2, NiSi2, or β-FeSi2 at much lower growth temperatures than possible in conventional solid-phase reaction of a metal layer deposited onto Si at room temperature (i.e., lower than the nucleation temperature). Moreover, epitaxial growth of CoSi2/Si(100), which is not possible by solid-phase reaction, becomes achievable when depositing Co atoms sufficiently slowly onto a heated Si substrate.

Heteroepitaxial ternary CoxY1−xSi1.7 silicide (x>0.27) has been formed by Co implantation into YSi1.7/Si(111). The formation of this compound is confirmed by an x-ray symmetric θ–2θ scan. However, the θ–2θ scan alone cannot discriminate between the possible phases (tetragonal, orthorhombic, or hexagonal) of this compound. On the other hand, Rutherford backscattering (RBS)/channeling confirms that this silicide is hexagonal and that its azimuthal orientation is CoYSi1.7[0001]//Si[111] and CoYSi1.7{1120}//Si{110}. In addition, the lattice constants of the ternary silicide aepi=0.3989 nm (which means that the lattice mismatch is >3.9% relative to the Si substrate) and cepi=0.3982 nm have been determined by RBS/channeling and x-ray diffraction.

An InGaN layer was grown by metalorganic chemical vapor deposition on a sapphire (0001) substrate using a thick (>2.2 μm) GaN intermediate layer. The In composition, which cannot be unambiguously determined by x-ray diffraction (XRD) or by photoluminescence, was determined by Rutherford backscattering (RBS). The perpendicular and parallel elastic strain of the In0.18Ga0.82N layer, e⊥=+0.21% and e∥=−0.53%, respectively, were derived using a combination of XRD and RBS/channeling. The small ratio |e⊥/e∥|=0.40 indicates that the In0.18Ga0.82N layer is much stiffer in the c-axis direction than in the a-axis direction.

Cobalt–iron transition-metal disilicides were investigated by Mossbauer effect and x-ray diffraction in order to determine the concentration range of their homogeneous and separate phase formation. Except at low Co or Fe concentrations, Co and Fe formed separate CoSi2 and FeSi2 phases. Up to 10 at % Co was found soluble in β-FeSi2; Fe dissolved in CoSi2 below 1.5 at % and was positioned at two different sites of cubic symmetry. The results obtained for the phase formation in thin layers of epitaxial CoSi2 on Si implanted with Fe were in agreement with the results obtained for the bulk samples.

Heteroepitaxial Nd0.32Y0.68Si1.7 layers with good crystalline quality (χmin of Nd and Y is 3.5% and 4.3%, respectively) have been prepared by high dose 65 keV Y and 80 keV Nd implantation into a Si(111) substrate using channeled ion beam synthesis. Although the disilicide of Nd only exists in a tetragonal or an orthorhombic phase which cannot be grown epitaxially on a Si(111) substrate, our results show that the addition of Y to the Nd–Si system forces the latter into a hexagonal structure. Rutherford backscattering/channeling and x-ray diffraction studies reveal that the lattice parameters of the Nd0.32Y0.68Si1.7 epilayer are aepi=0.3915 nm and cepi=0.4152 nm and that the epilayer is stable up to 950 °C. Annealing at 1000 °C results in partial transformation into other unidentified phases.

The reaction of Co with epitaxial SiGeC/Si layers is investigated and compared to the reaction of Co with SiGe/Si layers. The sequence of phase formation is the same as the reaction of Co with monocrystalline Si, however, cobalt disilicide is formed at much higher temperatures. The presence of C further delays the disilicide formation, as a result of C accumulation at the silicide/substrate interface during the reaction, which blocks the Co diffusion paths. The CoSi2 layers thus formed exhibit a preferential (h00) orientation. The slow supply of Co atoms to the silicide/Si interface, due to the blocking of Co diffusion paths by Ge and C, is believed to be the reason for this epitaxial alignment.

Ultrahigh vacuum evaporation of magnesium onto a hot silicon substrate (⩾200 °C), with the intention of forming a Mg2Si thin film by reaction, does not result in any accumulation of magnesium or its silicide. On the other hand, codeposition of magnesium with silicon at 200 °C, using a magnesium-rich flux ratio, gives a stoichiometric Mg2Si film which can be grown several hundreds of nm thick. The number of magnesium atoms which condense is equal to twice the number of silicon atoms which were deposited; all the silicon condenses while the excess magnesium in the flux desorbs. The Mg2Si layers thus obtained are polycrystalline with a (111) texture. From the surface roughness analysis, a self-affine growth mode with a roughness exponent equal to 1 is deduced.

Previous reports show that, among all rare‐earth silicides, GdSi1.7 is the most difficult one to grow epitaxially with a good crystalline quality on a Si substrate. However, this letter shows that by using channeled implantation, a continuous GdSi1.7 layer with good crystalline quality (χmin=10%) can be formed by implantation of 90 keV Gd ions in Si(111). Besides, the hexagonal phase of the GdSi1.7 layer is stable up to a temperature of 850 °C for 30 min, which is much more stable than previously reported. After annealing at temperatures ≥900 °C for 30 min, the hexagonal GdSi1.7 phase transforms into the orthorhombic GdSi2 phase. Rutherford backscattering/channeling, transmission electron microscopy, and x‐ray diffraction are used in this study.

166Er atoms were implanted with an energy of 70 to 90 keV and doses of 0.8 to 2.0×1017/cm2 into Si(111) substrates at temperatures ranging from 450 to 530 °C. We found that using conventional nonchanneled implantation at energies of ∼90 keV, it is impossible to form a continuous ErSi1.7 layer. At best, after annealing, a discontinuous ErSi1.7 layer with poor crystalline quality (χmin=40%) is obtained. On the contrary, using channeled implantation, a continuous epitaxial ErSi1.7 layer with very good crystalline quality can be formed; a lowest χmin value of 1.5% for a surface ErSi1.7 layer has been obtained. The origin of this different behavior is explained. Our results show that for synthesizing continuous ErSi1.7 layers with good quality using ion beam synthesis at energies around 90 keV, channeled implantation is indispensable.