Oxidation of indium implanted aluminium studied by the Rutherford backscattering and perturbed angular correlation methods

Aluminium foils oversaturated with 5.10¹⁵/cm² implanted¹¹⁵In⁺ ions were oxidized in 200 mbar oxygen or vacuum annealed at 370–870 K. The samples were analyzed by the Rutherford backscattering (RBS) and perturbed angular correlation (PAC) techniques, using some 10¹¹/cm² implanted radioactive¹¹¹In tracers. Furthermore, the oxygen surface profiles were also scanned with high resolution by using the nuclear resonance technique (NRA). The formation of passivating Al₂O₃ surface layers, preventing deeper oxygen diffusion and the indium diffusion into these oxidized surface layers and into the bulk, were studied. Several quadrupole interaction frequencies previously attributed to strained cubic indium precipitates and indium (-vacancy) clusters were observed. When the samples were oxidized above 750 K, the formation of In-O complexes and of substitutional¹¹¹In in Al₂O₃ was observed.     

Investigation of weak damage in Al0.25Ga0.75As/GaAs by using RBS/C and Raman spectroscopy

The weak damage induced by 0.8 MeV Si ion implantation in the Al_0.25Ga_0.75As films epitaxially grown on GaAs substrates was studied by using Rutherford backscattering spectrometry/channeling (RBS/C) and Raman spectroscopy. RBS/C spectra measured from the implanted samples showed rather low damage level induced by the ion implantation with ion dose from 1×10¹⁴ to 5×10¹⁵ cm⁻². The Raman spectra were measured on these samples. Two kinds of phonon modes, GaAs-like and AlAs-like, are observed, which indicate the existence of multiple phonon vibrational modes in the epitaxial Al_0.25Ga_0.75As films on the GaAs substrate. Compared with the unimplanted sample, the Raman photon peaks for the implanted sample shift gradually to lower energy with the increase of the implantation dose. The strains induced in the implanted layer were also evaluated from the Raman spectra. The result from high resolution double crystal X-ray diffractometry (HRXRD) also verified the evolution of the strains in the implanted layers.     

Preparation, structure, and properties of metal nanocomposites in lithium niobate

Crystals of lithium niobate LiNbO₃ are implanted with 60-keV Cu^? ions at different ion fluxes to a fluence of 2 × 10¹⁷ ions/cm². The structure and the linear and nonlinear optical properties of the implanted layers are investigated. The optical transmission and ion-induced photon spectra of the LiNbO₃ crystals are measured in the course of implantation. It is revealed that the implantation brings about the formation of complex nanocomposites consisting of metallic copper nanoparticles and nanodomains of the matrix. The distributions of nanoparticles and nanodomains in the implanted layers do not correlate with each other. It is shown that the variations in the linear and nonlinear optical absorption of the nanocomposites are predominantly determined by the changes in the chemical composition and the structure of the matrix.     

Optical reflection from dielectric layers containing metal particles formed by ion implantation

Dielectric layers with silver nanoparticles, which are synthesized in a soda-silicate glass by implantation of 60-keV ions with a dose of 7.0×10¹⁶ Ag⁺/cm² at an ion current density of 10 μmA/cm², are analyzed. The depth of silver distribution was measured by Rutherford backscattering. Data on optical characteristics of composite layers were obtained from the transmission spectra and from the reflection, which were measured both from the side of an implanted glass surface and from the unimplanted side. To calculate reflection spectra, a multilayer plane-parallel film structure was considered, which was modeled on the basis of the matrix method using complex Fresnel coefficients. Dielectric functions of separate layers were determined using the Maxwell-Garnet theory of an effective medium. A qualitative agreement between the experimental and the model optical spectra was obtained taking into account a nonuniform depth distribution of metal nanoparticles in a composite material.     

Optical properties of ZnO and Al2O3 implanted with silver ions

ZnO and Al₂O₃ samples implanted with 30-keV silver ions with fluences in the interval (0.25–1.00) × 10¹⁷ ions/cm² are studied by the method of optical photometry in the visible part of the spectrum. The optical transmission spectra of the implanted samples exhibit a selective band associated with surface plasmon resonance absorption of silver nanoparticles. The intensity of this band nonmonotonically depends on the implantation fluence. The silver ion depth distribution in the samples is calculated. It is shown that the non-monotonicity observed in experiments is due to an increase in the substrate sputtering ratio with increasing implantation fluence. It is found that vacuum thermal annealing of the implanted Al₂O₃ layers up to 700°C causes a considerable narrowing of the plasmon absorption bandwidth without a tangible change in its intensity. At higher annealing temperatures, the plasmon absorption band broadens and its intensity drops. Annealing of the ZnO films under such conditions causes their complete vaporization.     

Optical properties of metal nanoparticles synthesized in a polymer by ion implantation: A review

Polymer composite layers irradiated by 30-keV Ag⁺ ions with doses from 3.1×10¹⁵ to 7.5×10¹⁶ cm^?2 and an ion current of 4 µA/cm² are investigated. The composites were examined using Rutherford backscattering (RBS), transmission electron microscopy (TEM), and optical spectroscopy. As follows from electron microscopy and electron microdiffraction data, ion implantation is a promising tool for synthesizing silver nanoparticles in the surface region. The optical density spectra taken of these composites demonstrate that the silver nanoparticles exhibit unusually weak plasma resonance. The formation of silver nanoparticles in layers carbonized by ion implantation is considered. Based on the Mie theory, optical extinction spectra for silver particles in the polymer and carbon matrices are simulated and optical spectra for complex silver core-carbon sheath nanoparticles are calculated. The physics behind the experimental optical spectra of the composite is discussed.     

Thermal evolution of high dose iron implanted sintered alumina

Sintered plates of alumina have been implanted at room temperature with 110 keV⁵⁷Fe⁺ at a dose of 1.2×10¹⁷ ions.cm^?2. The analysis of the Conversion Electron Mössbauer Spectrum indicated that implantation introduces iron in alumina in three charge state: Fe²⁺ (two components), Fe⁴⁺ and Fe⁰ (metallic clusters). The evolution of the iron depth distribution during annealings in oxiding or in neutral atmosphere has been followed using the Rutherford backscattering spectroscopy. Up to 800°C the profile as well as the charge states of iron evolve very slowly. A drastic change occurs' for annealing temperature around 1000°C. The total amount of iron is distributed among α-Fe₂O₃ and α-(Fe_1?x Al _x )₂O₃ precipitates. Some scanning electron micrographs have allowed to locate these precipitates. For highest temperature anneals, up to 1600°C, only substitutional iron remain.     

纯锆上离子注入钇和镧后的表面分析

用金属蒸汽真空弧源，以40kV加速电压对纯锆样品分别进行了10¹⁶—10¹⁷/cm²的钇、镧离子注入，注入温度约为130℃.然后对注入样品进行表面分析.x射线光电子能谱分析表明，注入的钇以Y₂O₃形式存在，镧以La₂O₃形式存在.俄歇电子能谱表明，纯锆基体表面的氧化膜厚度随着离子注入剂量的增加而增加，当离子注入剂量达到10¹⁷/cm²时，氧化膜的厚度达到了最大值.卢瑟福背散射显示镧层的厚度约为30nm，同时直接观察到当离子注入剂量为(La+Y)10¹⁷/cm²时，纯锆样品表面发生了严重的溅射. 关键词： 纯锆 钇和镧离子共注入 卢瑟福背散射 x射线光电子能谱     

Dopant activation in Sb-implanted relaxed Si1−xGex alloy layers grown on compositionally graded buffers

Supersaturated solid solutions of substitutional, electrically active Sb have been obtained by ion implantation of relaxed epitaxial Si_1?xGe_x alloy layers grown on compositionally graded buffers. Substitutional and nonsubstitutional Sb fractions in relaxed Si_0.85Ge_0.15, Si_0.65Ge_0.35 and Si_0.50Ge_0.50 alloy layers implanted to a dose of 5×10¹⁵ Sb cm^?2 and annealed isothermally at temperatures ranging from 400 to 850°C have been studied by Rutherford backscattering/channeling, transmission electron microscopy and Hall-effect and sheet resistivity measurements. A supersaturated solution of Sb corresponding to a peak carrier concentration of 4×10²⁰ cm^?3 and an electrically active fraction of 40% of the implanted dose is observed by Hall measurements for the case of Si_0.85Ge_0.15 and Si_0.65Ge_0.35 alloys annealed at 550°C.     

Phase transition and pitting corrosion behaviour for Mo—implanted aluminium

Molybdenum ions are implanted into aluminium with high ion flux and high dose at elevated temperatures of 200℃, 400℃ and 500℃. Due to the high temperature and high flux of vacancies and interstitial atoms, the atom diffusion and chemical effects are enhanced during the ion implantation. The effects increase with increasing ion flux and dose, so that new phase formation and phase transition emerge noticeably. X-ray diffraction analysis shows that when the aluminium is implanted with Mo ions at a low ion flux (25μA/cm²), the Al₅Mo alloy is formed. The atomic ratio of Mo/Al of the Al₅Mo phase is close to 20%. When the aluminium is implanted with Mo ions at a high ion flux (50μA/cm²), the phase transition from Al₅Mo to Al₁₂Mo appears, and the latter is dominant, which is determined to be the final phase. The ratio of Mo/Al in Al₁₂Mo is 7.7%. Rutherford backscattering spectroscopy indicates also that the Mo/Al atom ratio is ～7% to ～8% in Mo-implanted aluminium. The atomic ratios of the constituents in Al₅Mo and Al₁₂Mo are of stoichiometric composition for these alloys. The thicknesses of the Al₁₂Mo alloy layers for Mo-implanted Al with ion doses of 3×10¹⁷/cm² and 1×10¹⁸/cm² are 550nm and 2000nm, respectively. The pitting corrosion potential V_p increases obviously. It is clear that due to the formation of Al₁₂Mo alloy layer, the pitting corrosion resistance is enhanced.     

Ion synthesis and laser annealing of Cu nanoparticles in Al2O3

Al₂O₃ samples with Cu nanoparticles, synthesised by ion implantation at 40 keV with a dose of 1×10¹⁷ ion/cm² and a current density from 2.5 to 12.5 μA/cm², were annealed using ten pulses from a KrF excimer laser with a single pulse fluence of 0.3 J/cm². The copper depth distribution, formation and modification of metal nanoparticles under the ion implantation and laser treatment were studied by Rutherford backscattering (RBS), energy dispersive X-ray (EDX) analysis, atomic force microscopy (AFM) and optical spectroscopy. It was found that laser annealing leads to a reduction in the nanoparticle size without diffusion of metal atoms into the bulk. The change in particle size and the possibility for oxidation of the copper particles are examined in the framework of Mie theory. Calculations presented show that under excimer laser treatment, Cu nanoparticles are more likely to be reduced in size than to undergo oxidation. Received: 19 April 2001 / Accepted: 7 November 2001 / Published online: 23 January 2002     

Structural and compositional changes in ion-bombarded Ta2O5

A detailed study of the effect of heavy-ion bombardment on Ta₂O₅ has been undertaken using a combination of radioactive tracer techniques, electron microscopy, and Rutherford backscattering. Crystalline Ta₂O₅ is amorphized at ~6 × 10¹³ ions cm^?2, while at a dose of ~5 × 10¹⁶ ions cm^?2 the electron microscopy reveals the development of random grains of a new crystalline phase. By ~1 × 10¹⁷ ions cm^?2 the grains are not yet overlapping but still yield a diffraction pattern consistent with either δ-Ta-O (not to be confused with TaO) or Ta_1?xO₂, thus indicating that Ta₂O₅, like most other transition-metal oxides, is subject to preferential sputtering. Preferential sputtering was confirmed by backscattering analysis of specimens bombarded to high doses, where the average surface composition was found to be Ta_1.8±0.2O₂ or, equivalently, Ta₂O_2.2±0.2. The surface alteration had an average composition independent of the mass and energy of the incident ions.     

The study of damage and optical properties in LiNbO3 implanted by MeV Er and He ions

Abstract

Two LiNbO₃ (X and Y cut) crystals from different companies were implanted by 3.0 MeV Er ions to a dose of 7.5 × 10¹⁴ ions/cm² and 3.5 × 10¹⁴ ions/cm² with different beam current densities, respectively. After annealing at 1060°C in air for 2 hours, one LiNbO₃ sample was implanted by 1.5 MeV He ions to a dose of 1.5 × 10¹⁶ ions/cm². The Rutherford backscattering/channeling and prism coupling method have been used to study the damage and optical properties in implanted LiNbO₃. The results show: (1) the damage in LiNbO₃ created by 3.0 MeV Er ions depends strongly on the beam current density; (2) after annealing at 1060°C in air for 2 hours, a good Er doped LiNbO₃ crystal was obtained; (3) there is waveguide formation possible in this Er-doped annealed LiNbO₃ after 1.5 MeV He ion implantation. It is suggested that annealing is needed to remove the damage created by MeV Er ions before the MeV He ion implantation takes place, to realize the waveguide laser for Er doped LiNbO₃.     

Damage profiles in LiNbO3 by low-energy H+ implantation

Low-energy 120 and 150 keV H⁺ was implanted in z-cut LiNbO₃ at room temperature. The fluence of H⁺ is 5?×?10¹⁶ ions/cm². The damage profiles in LiNbO₃ induced by implantation were investigated using Rutherford backscattering/channelling. The damage profiles were extracted using the channelling results. The experimental damage profiles in LiNbO₃ were analyzed and compared to the simulated results from TRIM. The results show a good consistency between experimental and simulated results. The present results are useful for the fabrication of H-implanted waveguides of oxide crystals, especially LiNbO₃.     

Changes induced by ion implantation in forsterite Sio4 Mg2

Abstract

The various methods of optical absorption spectroscopy, Rutherford back-scattering, transmission electron microscopy and X-ray diffraction, have been associated to study the high-dose ion implantation (150 keV, 10¹⁷ ions cm^?2) phenomena in SiO₄Mg₂ single crystals. After thermal annealing at high temperature under vacuum or in atmosphere, different new phases appear:

For an under vacuum anneal, the formation of solid solution is observed: SiO₄ (Mg, Fe)₂ by X-ray diffraction;

For atmospheric anneal precipitates a spinelle phase of Fe₃O₄ or Mg Fe₂O₄.

Preliminary results on the mechanical properties studied by creep technique will be discussed for these implanted and annealed crystals.     

Formation and growth of embedded indium nanoclusters by In<Superscript>2<Emphasis Type="Bold">+</Emphasis></Superscript> implantation in silica

Indium nanoclusters are synthesized in an amorphous silica matrix using an ion-implantation technique. Indium ions (In²⁺) with energy of 890 keV are implanted on silica to fluences in the range of 3×10¹⁶–3×10¹⁷ cm^-2. The formation of indium nanoclusters is confirmed by optical absorption spectrometry and glancing incidence X-ray diffraction studies. A low frequency Raman scattering technique is used to study the growth of embedded indium nanoclusters in the silica matrix as a function of fluence and post-implantation annealing duration. Rutherford backscattering spectrometry studies show the surface segregation of implanted indium. Photoluminescence studies indicate the formation of a small quantity of indium oxide phase in the ion-implanted samples. PACS 85.40.Ry; 78.67.Bf; 73.20.Mf; 82.75.Fq     

Synthesis of silicon dioxide layers by high dose ion implantation

Single crystal <100> silicon was implanted with molecular oxygen with energies ranging from 80 to 240 keV in a non-channeling direction. Rutherford backscattering (RBS) analysis was used to obtain the oxygen/silicon atomic ratio depth profiles and the thickness of the buried oxide layer, for doses ranging from 10¹⁶ to 1. 5 × 10¹⁸ O₂+/cm². This work links the early low energy work and the more recent higher energy work, and generally excellent agreement has been obtained. The minimum energy for formation of buried silicon dioxide has been identified as 160 keV per oxygen molecule and corresponding oxygen dose of 6 × 10¹⁷ O₂+/cm₂.     

Synthesis of chromium silicide with laser pulses

Thin chromium films, 60 nm thick, were deposited onto single-crystal silicon wafers. The samples were irradiated with 30 ns single pulses from a Nd: glass laser at fluences ranging from 0.4 to 2.25 J/cm². Rutherford backscattering spectrometry, transmission electron microscopy and electron diffraction measurements evidence the formation of CrSi₂ layers at the Cr/Si interface. The silicide thickness depends on the laser fluence.     

ZnO nanoparticle creating in a SiO2/Si structure using the Zn ion implantation with subsequent heat treatment

The distribution profiles of the dopant in the surface layer of a SiO₂/Si structure implanted with Zn and O ions are studied via Rutherford backscattering spectroscopy for He²⁺ ions using the channeling technique. The redistribution of implanted impurities in the Si surface layer during the formation process of zinc oxide (ZnO) nanoparticles is analyzed. The effect of the annealing temperature on the formation process and growth of ZnO nanoparticles is studied. The sample-surface morphology is examined via atomic force microscopy. The optical absorption and photoluminescence of the implanted layers are studied.     

Investigation of the inhibiting outdiffusion of erbium atoms to a silicon-on-insulator surface after annealing at high temperature

The annealing behaviour of 400 keV Er ions at a fluence of 2×1015 cm-2 implanted into silicon-on-insulator(SOI) samples is investigated by Rutherford backscattering spectrometry of 2.1 MeV He2+ ions with a multiple scattering model.It is found that the damage close to the SOI surface is almost removed after being annealed in O2 and N2 atmospheres,successively,at ℃,and that only a small number of the Er atoms segregated to the surface of the SOI sample,whereas a large number of Er atoms diffused to a deeper position because of the affinity of Er for oxygen.For the SOI sample co-implanted with Er and O ions,there is no evident outdiffusion of Er atoms to the SOI surface after being annealed in N2 atmosphere at ℃.