Low Energy Oxygen Ion Research Articles

Amendment the surface structure and optical properties of Makrofol LT by low energy oxygen ion bombardment

Ion beam bombardment is a powerful technique to improve the surface properties of polymeric materials without changing the bulk properties. Herein, Makrofol LT films were bombarded with low energy of oxygen ions at different fluences ranging from 11 × 1017 to 44 × 1017 ions/cm2. X-ray diffraction, FTIR spectroscopy, surface-roughness tester, ultraviolet–visible spectroscopy, and Fluorescence spectroscopy were used to examine the change in the structure, chemical functional groups, alteration in surface roughness parameters, and photo-physical properties. The obtained results evidenced that the ordering and disordering structure of bombarded Makrofol LT films were influenced by ion beam irradiation according to the ion fluence. The FTIR spectroscopy of functional group examination revealed the possibility of the presence of sp2-carbon clusterization and amorphization. The surface roughness parameters increase as the ion fluences increase. Optical measurements exhibit a shift of absorption-edge towards the visible zone that correlated to the surface damage and the creation of CC bonds. The fluorescence spectra exhibit that the yield intensities decrease with increasing ion fluences. This refers to improvement in the radiative-recombination rate relative to non-radiative recombination. This is attributable to the growth of clusters, the increase of density states of the surface, and the increase in the surface roughness of the bombarded samples.

Low-energy oxygen ion beam induced chemical vapor deposition using methylsilane or dimethylsilane for the formation of silicon dioxide films

In this study, the ion beam induced chemical vapor deposition method was employed for silicon dioxide (SiO2) film formation using methylsilane (MS) or dimethylsilane (DMS). In a reaction chamber of our ion beam system, O+ ions together with MS or DMS were supplied to a substrate at room temperature. The O+ ion beam had an energy of 100 eV. After the experiment, a film was found to be deposited on the substrate in both MS and DMS cases. The thickness of the resulting film was 60 nm. The results obtained by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) showed that for both MS and DMS, the films were composed of SiO2. In the MS case, XPS data of the film showed that a small amount of carbon was included in the film. On the contrary, in the DMS case, a relatively large amount of carbon was included in the film.

Oxidation of Thallium by Low-Energy Oxygen Ions

Oxidation of Thallium by Low-Energy Oxygen Ions

Оже-анализ оксида таллия, сформированного с использованием низкоэнергетического пучка ионов кислорода

The effect of irradiation with low-energy oxygen ions on the composition and some properties of the layer formed on the thallium surface has been studied. It is shown that bombardment with oxygen ions leads to the formation of a two-dimensional oxide layer, which effectively passivates the surface.

Auger analysis of thallium oxide formed using a low-energy beam of oxygen ions

The effect of irradiation with low-energy oxygen ions on the composition and some properties of the layer formed on the thallium surface has been studied. It is shown that bombardment with oxygen ions leads to the formation of a two-dimensional oxide layer, which effectively passivates the surface. Keywords: layer, spectroscopy, surface, energy, composition, bombardment.

Thermal stability of oxygen functionalization in v-CNTs by low kinetic energy ion irradiation

Vertically aligned multiwalled carbon nanotubes synthetized by catalytic chemical vapor deposition are irradiated with low kinetic energy oxygen ions to graft oxygen functional groups at their surface. Subsequently, the thermal stability of these functional groups is investigated by heating the sample progressively to 200, 300, 400 and 500 °C. X-Ray photoelectron spectroscopy (XPS) is used to analyze the atomic concentration and chemical configuration at the sample surface after each stage. Scanning and transmission electron microscopies are used to observe the morphology of the nanotubes after the thermal treatment. The solvent-free functionalization is carried out in 10 min reaching an oxygen atomic concentration of 17.2 at.%, with no impurities introduced. At the end of the thermal treatment, the relative oxygen content drops to 5.6 at.%. XPS analysis indicates that four oxygen groups produced by the ion irradiation: epoxide, hydroxyl, carbonyl, and carboxyl groups, with the epoxides being the least stable and the carbonyls the most stable. Combining low kinetic energy ion-irradiation with a post-thermal anneal is shown to be an effective route to simultaneously control both sample oxygen content and the ratio of different oxygenated functional groups.

Enhancement of photosensitivity of thermally evaporated crystalline PbS thin films by low energy oxygen ions implantation

This study presents the effect of low energy (120 KeV) O-ions implantation on the photosensitivity of PbS thin films by vacuum thermal evaporator (VTE). The crystallite size (D) of PbS films decreased from 32.8 nm to 17.4 nm and the bandgap (E g) increased from 1.61 eV to 1.76 eV as the fluence increased from 0.5 × 1016 ions cm−2 to 1.5 × 1016 ions cm−2. The PL spectra of O-ions implanted PbS thin films showed a dominant peak at 381 nm regardless the fluence of implantation. The photocurrent sharply increased by the implantation of O-ions (0.5 × 1016 ions cm−2) due to the creation of ‘shallow traps’ in the forbidden gap of PbS thin films under illumination of visible light (100 mW cm−2). The highest photosensitivity of O-ions implanted PbS thin films was observed due to the creation of proper traps for the photoconduction for the particular dose of 0.5 × 1016 ions cm−2.

EFFECT OF LOW-ENERGY OXYGEN ION BEAM TREATMENT ON THE STRUCTURAL AND PHYSICAL PROPERTIES OF ZnO THIN FILMS

In this paper, we report the influence of low-energy oxygen ion irradiation with fluence ranging from [Formula: see text][Formula: see text][Formula: see text] to [Formula: see text][Formula: see text][Formula: see text] on the structural, optical, and electrical properties of fresh and annealed (400∘C, 3[Formula: see text]h) zinc oxide (ZnO) thin films. These films were grown on soda-lime glass (SLG) substrates using the spin-coating method as a low-cost depositing technique. X-ray diffraction (XRD) study showed the formation of the hexagonal phase of ZnO thin films with preferred orientation along the (002) plane. The crystallite size for fresh and annealed ZnO thin films was in nanoscale and it increased with the annealing temperature. Also, the crystallite size increased with the ion beam irradiation fluence in the case of annealed ZnO films, while it slightly decreased for the fresh ZnO films. The transmittance and absorbance spectra for the ZnO films were investigated in a wide wavelength range. The optical bandgap was specified by using Tauc’s relation. The electrical properties of the ZnO films (fresh and annealed at 400∘C for 3[Formula: see text]h) were studied before and after the oxygen ion beam irradiation. Also, the dielectric properties were investigated with respect to frequency at different ion beam irradiation fluences. The comprehensive results showed the dielectric and optical properties are improved due to the induced conductive networks by oxygen ion irradiation.

AFM and Raman study of graphene deposited on silicon surfaces nanostructured by ion beam irradiation.

Nanoscale structures were produced on silicon surfaces by low-energy oxygen ion irradiation: periodic rippled or terraced patterns formed spontaneously, depending on the chosen combination of beam incidence angle and ion fluence. Atomic force microscopy image processing and analysis accurately described the obtained nanotopographies. Graphene monolayers grown by chemical vapour deposition were transferred onto the nanostructured silicon surfaces. The interfacial interaction between the textured surface and the deposited graphene governs the conformation of the thin carbon layer; the resulting different degree of regularity and conformality of the substrate-induced graphene corrugations was studied and it was related to the distinctive topographical features of the silicon nanostructures. Raman spectroscopy revealed specific features of the strain caused by the alternating suspension and contact with the underlying nanostructures and the consequent modulation of the silicon-graphene interaction. Lay Description In the field of nanosciences, nanotechnologies and advanced materials, it is pivotal to produce and integrate nanostructures in a controlled, cost-effective and possibly high-throughput manner. Currently, the surface nanopatterning by ion beam irradiation (IBI) is showing its potential in overcoming some of the limits that characterize the conventional lithographic techniques. IBI can produce self-organized and regular patterns of nanostructures, such as ripples, dots, and holes, having heights and lateral periodicities in a pre-defined range. The nanopatterns can develop over large surface areas of a broad class of materials and have been tested for different applications, e.g. microelectronic device fabrication, catalysis, nanoscale magnetism, surface-enhanced Raman scattering. Also, the ion-induced patterns allowed the control of physical properties such as wettability, reflectance, and photoluminescence. As a whole, this is a highly dynamic and continuously evolving field. Graphene was first obtained from bulk graphite by mechanical exfoliation; remarkable mechanical, thermal and optical properties came to light; they make graphene an ideal material for sensing. Also, the research on graphene paves the way for basic and applied studies on other ultrathin thickness materials, such as monolayer transition metal dichalcogenide or monolayer metal oxide, which also show peculiar properties as compared to their bulk version. Since graphene is a zero-gap semi-metal, a finite energy gap must be open to engineer graphene-based electronic devices. At this aim, researchers can take advantage of the mechanical properties of graphene, since its out-of-plane deformation can favourably modify its electronic structure. While the spontaneous, random self-folding of graphene to form wrinkles has thermodynamics reasons and is unavoidable above a certain material length, the interactions between graphene and substrates can generate, in principle, designed wrinkled structures. Therefore, a field of study has emerged, focused on the control and tuning of the geometry of graphene corrugations and their influence on specific physical and chemical properties. To the best of our knowledge, this work studies for the first time the geometry and strain in graphene wrinkles induced by silicon substrates that were suitably nanopatterned by ion beam irradiation.

Properties of secondary particles for ion beam sputtering of silicon using low-energy oxygen ions

The properties of secondary particles for sputtering silicon with primary low-energy oxygen ions were investigated with dependence on the primary ion energy Eion and geometric parameters (ion incidence angle, polar emission angle, and scattering angle). The mass and energy distributions of the secondary particles were measured by energy-selective mass spectrometry. The experimental results were compared with simulations using the Monte Carlo code sdtrimsp and with calculations based on a simple elastic binary collision model. The main secondary ion species were found to be O+, O2+, Si+, and SiO+. Their energy distribution functions depend on the primary ion energy Eion and the scattering angle γ. For O+, Si+, and SiO+ ions, a decreasing scattering angle γ or an increasing primary ion energy Eion leads to a pronounced feature in the high-energy part of the distributions. The energy distributions of the secondary O2+ ions show hardly any changes with regard to the primary ion energy or the scattering angle γ. In the case of the O+ ions, the energy distribution appears to reflect several direct scattering channels, which could be associated with the primary ion energy Eion, and half of the ion energy Eion/2. The present experimental results are compared with previous investigations for the sputtering of Si with the noble gas ions, such as Ne+, Ar+, and Xe+.

Near-threshold, steady state interaction of oxygen ions with transition metals: Sputtering and radiation enhanced diffusion

Transition metals used in semiconductor, photolithography and fusion applications interact with low energy oxygen ions. Understanding erosion, the nature of the formed oxide and depth of oxygen transport is necessary in mitigating unexpected performance of sensors, optics or plasma facing components. Oxide formation is governed by both the ion–target combination and the incident ion energy. We study the interaction of the transition metals molybdenum, ruthenium, palladium and tungsten, with oxygen ions in the energy region of 50–500 eV. Near-threshold sputtering of metals was experimentally measured and compared to predictions by the Monte Carlo code TRIDYN. Compositional changes and oxide thicknesses following sputtering were measured using Angle resolved X-ray photoelectron spectroscopy and subsequently compared to limiting oxide formed by atomic oxygen exposures. Sputter yields in some cases (ruthenium) were found to be sensitive to ion beam impurities such as ozone (<1% of background gas) leading to chemical sputtering. Ion induced oxide thicknesses (for molybdenum and tungsten) were found to be larger than those predicted by ballistic transport where sputtering is balanced by implantation. It is hypothesized that radiation enhanced diffusion of free oxygen leads to thicker oxide films at low ion energies.

Low Kinetic Energy Oxygen Ion Irradiation of Vertically Aligned Carbon Nanotubes

Vertically aligned multiwalled carbon nanotubes (v-CNTs) were functionalized with oxygen groups using low kinetic energy oxygen ion irradiation. X-ray photoelectron spectroscopy (XPS) analysis indicates that oxygen ion irradiation produces three different types of oxygen functional groups at the CNTs surface: epoxide, carbonyl and carboxyl groups. The relative concentration of these groups depends on the parameters used for oxygen ion irradiation. Scanning electron microscopy (SEM) shows that the macroscopic structure and alignment of v-CNTS are not affected by the ion irradiation and transmission electron microscopy (TEM) proves tip functionalization of v-CNTs. We observed that in comparison to oxygen plasma treatment, oxygen ion irradiation shows higher functionalization efficiency and versatility. Ion irradiation leads to higher amount of oxygen grafting at the v-CNTs surface, besides different functional groups and their relative concentration can be tuned varying the irradiation parameters.

An investigation of luminescence properties of gamma, ultraviolet and ion-beam irradiated phosphor KCaBO3:Dy

Potassium calcium borate doped with dysprosium was synthesized by solid state diffusion method. Phase determination and compound confirmation were done by x-ray diffraction (XRD). Crystallite size calculated using Scherrer's formula was found to be around 117 nm. Other characteristics were studied using techniques like field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). Band gap of the material was determined using ultraviolet–visible diffuse reflectance spectroscopy (UV-VIS DRS). The phosphor KCaBO3:Dy was irradiated by photon beams (of 1.25 MeV gamma and 4.88 eV UV rays) and ion beams (of 65 MeV and 85 MeV of O6+ and 75 MeV of C6+) with different doses in order to study its thermoluminescence (TL) properties. The phosphor showed good TL sensitivity towards these ionizing radiations. A good linear dose response was also shown by the phosphor for photon beam exposure. However, in case of ion beams exposure, dose response of the phosphor was good only for low energy oxygen ion beam. Also the phosphor showed good photoluminescence (PL) property with sharp peaks present in the PL emission and excitation spectra corresponding to the characteristic peaks of the dopant Dy. The Commission International de l’E clairage (CIE) was also used to calculate chromaticity coordinates and color temperature in order to investigate the phosphor's application in white LEDs. All these good characteristics make this phosphor a suitable candidate for radiation dosimetry and solid state lighting.

Formation of oxides on CoCrMo surfaces at room temperature: An XPS study

We have studied the initial stages of oxide formation on CoCrMo surfaces, exposed to oxygen environment or bombarded by low-energy oxygen ions at room temperature (RT), using x-ray photoemission spectroscopy (XPS) around Co 2p, Cr 2p and Mo 3d core-levels. The results are compared with the oxidation of pure Co, Cr and Mo metals from the literature. While the oxidation of all three metals from CoCrMo in oxygen atmosphere follows the logarithmic growth kinetics, characteristic for the electric field driven migration of metal cations or oxygen anions, oxidation induced by low-energy oxygen ions follows the parabolic growth rate.

Surface characteristics of a dental implant modified by low energy oxygen ion implantation

The good biocompatibility of Titanium-based medical device is related to the thin oxide layer (titanium dioxide, TiO2) formed on the surface. In this study, Plasma Immersion Ion Implantation (PIII) method and Optical Emission Spectrometer (OES) were used to produce oxidized surface in order to study the influence of plasma composition on surface composition. The result of OES showed that higher electron temperature, more metastable argon atom and oxygen ion content facilitate the formation of TiO2 top surface. The treated implant surfaces possessed higher content Ti2O3, lower contact angle. When the atomic percentage of Ti2O3 is similar to the TiO2, the contact angle is close to zero, which could attribute to the photocatalytic activity of self-doped TiO2−x. It generates more hydroxyl groups under visible light, causing a decrease in contact angle. But release of titanium ions was found in some solutions. It is believed that the TiO2−x produced by low energy oxygen ion implant has super hydrophilic properties, which indicates the potential for improved implant osseointegration in vivo.

The use of ion irradiation to control the thickness of thin superconducting films

Low energy oxygen ion beam irradiation was used to decrease the thickness of 5 nm NbN film. It was shown that the irradiation-induced NbN oxidation thickness was controlled by the full projected range of oxygen ions. High Resolution TEM (HRTEM) images analysis and Electron Energy Loss Spectroscopy (EELS) techniques on FIB-cut cross section samples were used to monitor the process of the NbN top layer oxidation under irradiation.

Suppression of self-organized surface nanopatterning on GaSb/InAs multilayers induced by low energy oxygen ion bombardment by using simultaneously sample rotation and oxygen flooding

Time of flight secondary ion mass spectrometry (ToF-SIMS) is a well-adapted analytical method for the chemical characterization of concentration profiles in layered or multilayered materials. However, under ion beam bombardment, initially smooth material surface becomes morphologically unstable. This leads to abnormal secondary ion yields and depth profile distortions. In this contribution, we explore the surface topography and roughening evolution induced by O2+ ion bombardment on GaSb/InAs multilayers. We demonstrate the formation of nanodots and ripples patterning according to the ion beam energy. Since the latter are undesirable for ToF-SIMS analysis, we managed to totally stop their growth by using simultaneously sample rotation and oxygen flooding. This unprecedented coupling between these two latter mechanisms leads to a significant enhancement in depth profiles resolution.

Directional etch of magnetic and noble metals. II. Organic chemical vapor etch

Surface oxidation states of transition (Fe and Co) and noble (Pd and Pt) metals were tailored by controlled exposure to O2 plasmas, thereby enabling their removal by specific organic chemistries. Of all organic chemistries studied, formic acid was found to be the most effective in selectively removing the metal oxide layer in both the solution and vapor phase. The etch rates of Fe, Co, Pd, and Pt films, through an alternating plasma oxidation and formic acid vapor reaction process, were determined to be 4.2, 2.8, 1.2, and 0.5 nm/cycle, respectively. Oxidation by atomic oxygen was an isotropic process, leading to an isotropic etch profile by organic vapor. Oxidation by low energy and directional oxygen ions was an anisotropic process and thus results in an anisotropic etch profile by organic vapor. This is successfully demonstrated in the patterning of Co with a high selectivity over the TiN hardmask, while preserving the desired static magnetic characteristic of Co.

Spectral Characteristics of Ultrafine Particles Zn2 SiO4-Mn, Precipitated From an Aqueous Solution on the Substrate in Electric or Magnetic Fields

The spectral parameters ultrafine particles Zn2SiO4-Mn, precipitated on the substrate in a magnetic or electric field have been investigated. For getting fine particles industrial phosphor K-60 (Zn2SiO4-Mn) was used. Luminescence spectra were obtained on a sample when exposed to ultraviolet light or a beam of charged oxygen ions. When excited by ultraviolet spectral characteristics have difference for samples with different dimensions of the crystals. As for the industrial design luminescence spectrum had a band with λmaх = 521 nm, and for the ultrafine crystals willemite spectral band had λmax = 550 nm. Analysis ionoluminescence spectra showed that the reduction of crystal size Zn2SiO4-Mn not affect the spectral characteristics of the excitation beam with low energy oxygen ions. The luminescence spectrum when exposed to low-energy ions (1-3 KeV) has a band with λmax = 521 nm and a half-width Δλ = 41 nm. When measuring the width of the forbidden zone has been established bandgap dependence on the size of the phosphor crystals. The width of the band gap increases with decreasing crystal size to nanoscale sizes. A significant effect was obtained when deposited on a substrate in the nanoscale crystal magnetic or electric field. As for the industrial design the bandgap was 4.16 eV, and for the besieged in the magnetic and electric field of 4.27, 4.29 eV, respectively.

SIMS depth profiling and topography studies of repetitive III–V trenches under low energy oxygen ion beam sputtering

Chemical depth profiling of III–V trenches containing InGaAs quantum wells with AlAs barriers selectively grown inside SiO2 cavities was studied using magnetic secondary ion mass spectrometry (SIMS). The authors show that the depth resolution of SIMS profiles of III-As layers degrades under extremely low energy oxygen beam sputtering (&amp;lt;500 eV) due to ripple formation and an increase in surface roughness. Improved SIMS depth resolution was observed by increasing the incident angle (∼50°–65°). Finally, the authors report the effect of sample rotation and orientation of the ion beam with respect to the trenches on depth profiling of III-As layers using time-of-flight SIMS.