Search

• Sequential Au and Ag ion implantation of 260 nm thick TiN films was performed. • The implantation was done using high ion fluences of Ag (200 keV) and Au (150 keV). • The TiN surface undergoes topographic and chemical changes after ion implantation. • Spherical and crystalline particles with the diameter below 15 nm were formed. • STEM showed that the obtained nanoparticles are Au-Ag alloys. Formation of Au-Ag alloy nanoparticles in TiN thin films is demonstrated through sequential implantation of Au and Ag ions. The irradiations were done with 200 keV Au ions at fluence of 1.0 × 1016 ions/cm2 and 150 keV Ag ions to the fluences in the range of 0.7–1.3 × 1017 ions/cm2. It was found that irradiations introduce around 1.5 at.% of gold and up to ~20 at.% of silver species causing also the significant sputtering of the surface. TiN surface besides the topographic undergoes chemical changes. The presence of silver and gold is confirmed by photoemission spectroscopy showing that the implanted ions did not form any kind of compound with the surrounding matrix. Electron microscopy evidenced the formation of crystalline and quasi-spherical particles with dimensions below 10 nm. Elemental analysis revealed that the obtained nanoparticles present Au-Ag alloys, with two elements mixed over the whole volume of the particles in different Au:Ag ratios. [ABSTRACT FROM AUTHOR]

• Si substrate was implanted sequentially with Au and Ag ions at different fluences. • Nanoparticles were found at maximum distribution depths of Au and Ag ions. • Ag nanoparticles aggregate in the silicon matrix along with the dissolved Au atoms. • The size of formed nanoparticles was controlled by varying Ag ion fluence. • HAADF contrast imaging was used to confirm the formation of Au-Ag alloy structure. Au-Ag alloy nanoparticles were formed into amorphous silicon by sequential ion implantation of Au and Ag. Monocrystalline Si was amorphized at the initial moment of implantation with 1 × 1016 ions/cm2 gold ions, and then different silver fluences were applied in the range of 1 × 1016–1 × 1017 ions/cm2. After implantations the samples were investigated by means of Rutherford backscattering spectrometry and transmission electron microscopy. The nanoparticles were found to be formed at surface and sub-surface regions of the Si substrate, at depths corresponding to the maximum distribution of Au and Ag ions. The particles are crystalline in nature with sizes from 2 nm to 30 nm in diameter, increasing with silver ion fluence. Although the lattice constants of gold and silver are too close to be distinguished by measuring the characteristic interplanar spacings, imaging in scanning transmission mode confirms the formation of Au-Ag bimetallic nanoparticles, presenting a solid-solution alloy of gold and silver. [ABSTRACT FROM AUTHOR]

Titanium nitride (TiN) thin films thickness of ∼260 nm prepared by dc reactive sputtering were irradiated with 200 keV silver (Ag) ions to the fluences ranging from 5 × 10 15 ions/cm 2 to 20 × 10 15 ions/cm 2 . After implantation TiN layers were annealed 2 h at 700 °C in a vacuum. Ion irradiation-induced microstructural changes were examined by using Rutherford backscattering spectrometry, X-ray diffraction and transmission electron microscopy, while the surface topography was observed using atomic force microscopy. Spectroscopic ellipsometry was employed to get insights on the optical and electronic properties of TiN films with respect to their microstructure. The results showed that the irradiations lead to deformation of the lattice, increasing disorder and formation of new Ag phase. The optical results demonstrate the contribution of surface plasmon resonace (SPR) of Ag particles. SPR position shifted in the range of 354.3–476.9 nm when Ag ion fluence varied from 5 × 10 15 ions/cm 2 to 20 × 10 15 ions/cm 2 . Shift in peak wavelength shows dependence on Ag particles concentration, suggesting that interaction between Ag particles dominate the surface plasmon resonance effect. Presence of Ag as second metal in the layer leads to overall decrease of optical resistivity of TiN. [ABSTRACT FROM AUTHOR]

Reactively sputtered CrN layer, deposited on Si(1 0 0) wafer, was implanted at room temperature with 80-keV V + ions to the fluence of 2 × 10 17 ions/cm 2 . After implantation the sample was annealed in a vacuum, for 2 h at 700 °C. The microstructure and chemical composition of CrN films was investigated using Rutherford backscattering spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and cross-sectional transmission electron microscopy (conventional and high-resolution), together with fast Fourier transformation analyses. It was found that vanadium atoms are distributed in the sub-surface region of CrN layer, with the maximum concentration at ∼20 nm. After annealing the formation of VN nanoparticles was observed. The nanoparticles are spherical shaped with a size of 8–20 nm in diameter. [ABSTRACT FROM AUTHOR]

Abstract: Studies on ion-irradiated transition-metal/silicon bilayers demonstrate that interface mixing and silicide phase formation depend sensitively on the ion and film parameters, including the structure of the metal/Si interface. Thin Co layers e-gun evaporated to a thickness of 50nm on Si(100) wafers were bombarded at room temperature with 400-keV Xe+ ions at fluences of up to 3×1016 cm−2. We used either crystalline or pre-amorphized Si wafers the latter ones prepared by 1.0-keV Ar-ion implantation. The as-deposited or Xe-ion-irradiated samples were then isochronally annealed at temperatures up to 700°C. Changes of the bilayer structures induced by ion irradiation and/or annealing were investigated with RBS, XRD and HRTEM. The mixing rate for the Co/c-Si couples, Δσ 2/Φ =3.0(4)nm4, is higher than the value expected for ballistic mixing and about half the value typical for spike mixing. Mixing of pre-amorphized Si is much weaker relative to crystalline Si wafers, contrary to previous results obtained for Fe/Si bilayers. Annealing of irradiated samples produces very similar interdiffusion and phase formation patterns above 400°C as in the non-irradiated Co/Si bilayers: the phase evolution follows the sequence Co2Si→CoSi→CoSi2. [Copyright &y& Elsevier]

Abstract: The present study deals with CrN/Si bilayers irradiated at room temperature (RT) with 120keV Ar ions. The CrN layers were deposited by d.c. reactive sputtering on Si(100) wafers, at different nitrogen partial pressures (2×10−4, 3.5×10−4 and 5×10−4 mbar), to a total thickness of 240–280nm. The substrates were held at room temperature (RT) or 150°C during deposition. After deposition the CrN/Si bilayers were irradiated up to fluences of 1×1015 and 1×1016 ions/cm2. Structural characterization was performed with Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM) and grazing angle X-ray diffraction (XRD). For the highest nitrogen pressure (5×10−4 mbar) a pure stoichiometric CrN phase was achieved. The results showed that Ar ion irradiation resulted in the variation of the lattice constants, micro-strain and mean grain size of the CrN layers. The observed microstructural changes are due to the formation of the high density damage region in the CrN thin film structure. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a study of the structure and composition of reactively sputtered Cr-N layers as a function of deposition parameters, and the effects of ion implantation on these structures. The layers were deposited on (100) Si substrates to a thickness of 240–280nm, at different nitrogen partial pressure, and subsequently irradiated with 120keV Ar ions. Structural characterisation of the samples was performed with Rutherford backscattering spectroscopy, transmission electron microscopy and X-ray diffraction analysis. We also measured their electrical resistivity with a four point probe. It was found that the layers grow in form of columnar structures, and their composition, Cr2N or CrN, strongly depends on the nitrogen partial pressure during deposition. Ion irradiation induces local micro-structural changes, formation of nano-particles and defects, which can be nicely correlated to the measured electrical resistivity. [Copyright &y& Elsevier]

Abstract: This paper reports on a study of microstructrual changes in TiN/Si bilayers due to 200keV Ar+ ions irradiation at room temperature. The 240nm TiN/Si bilayers were prepared by d.c. reactive sputtering on crystalline Si (100) substrates. The TiN films were deposited at the substrate temperature of 150°C. After deposition the TiN/Si bilayers were irradiated to the fluences of 5×1015 and 2×1016 ions/cm2. The structural changes induced by ion irradiation in the TiN/Si bilayers were analyzed by Rutherford Backscattering Spectroscopy (RBS), X-ray diffraction analyses (XRD) and Transmission Electron Microscopy (TEM). The irradiations caused the microstructrual changes in TiN layers, but no amorphization even at the highest argon fluence of 2×1016 ions/cm2. It is also observed that the mean crystallite size decreases with the increasing ion fluence. [Copyright &y& Elsevier]

Abstract: A study of ion beam modification of structural and electrical properties of TiN thin films is presented. The layers were deposited by reactive ion sputtering on (100) Si and glass slide substrates to a thickness of ∼240nm. After deposition the structures were implanted with argon ions at 120keV, to the fluences from 1×1015 to 1×1016 ions/cm2. The ion energy was chosen to give the projected ion range within the deposited layers, to minimize the influence of the substrate on the induced structural changes. Structural analysis of the samples was performed by cross-sectional transmission electron microscopy, X-ray diffraction and Rutherford backscattering spectrometry. Electrical characterization included sheet resistivity measurements with a four point probe. It was found that the as-deposited layers have a columnar structure, individual columns stretching from the substrate to the surface and being a few tens of nanometers wide. Ion irradiation rearranges their crystalline structure, which remains polycrystalline, but the columns are broken, and nanocrystals of the same phase are formed. The structural changes can be nicely correlated to the measured electrical resistivity. [Copyright &y& Elsevier]