Energy Nitrogen Ion Research Articles

Influence of Surface Sputtering during High-Intensity, Hot Ion Implantation on Deep Alloying of Martensitic Stainless Steel

This article is devoted to the study of the effect of ion sputtering on the alloy surface, using the example of martensitic stainless steel AISI 420 with ultrahigh-dose, high-intensity nitrogen ion implantation on the efficiency of accumulation and transformation of the depth distribution of dopants. Some patterns of change in the depth of ion doping depending on the target temperature in the range from 400 to 650 °C, current density from 55 to 250 mA/cm2, and ion fluence up to 4.5 × 1021 ion/cm2 are studied. It has been experimentally established that a decrease in the ion sputtering coefficient of the surface due to a decrease in the energy of nitrogen ions from 1600 to 350 eV, while maintaining the ion current density, ion irradiation fluence and temperature mode of target irradiation increases the ion-doped layer depth by more than three times from 25 μm to 65 µm. The efficient diffusion coefficient at an ion doping depth of 65 μm is many times greater than the data obtained when stainless steel is nitrided with an ion flux with a current density of about 2 mA/cm2.

Augmented electrochemical properties of manganese oxide nanorods on low energy nitrogen ion irradiation

For the development of versatile and high-performance storage devices, nanorods-based supercapacitors hold great promise due to their high energy density per unit volume and their resilience in the face of high mechanical stress. In this study, we demonstrated how to increase charge storage capacity by using an ion beam to join manganese oxide nanorods on a massive scale, thereby creating surface defects. Hydrothermally synthesized Mn3O4 nanorods were spin-coated on a silicon wafer and subjected to low energy (5 keV) N+ ion-beam at varying ion fluences before undergoing extensive electrochemical characterizations to verify their charge storage performance. At a mass normalized current of 10 A/g, the areal capacitance for pristine and irradiated Mn3O4 nanorods is 45 mF/cm2 and 132 mF/cm2. Hence, irradiated Mn3O4 nanorods were found to have better charge storage performance than their untreated counterparts. Insights into the improved charge-storage performance of irradiated nanorods are made clear by the detailed experimental findings. The irradiated sample further retains 90% of its initial capacitance for more than 5000 cycles of measurements. The enhanced areal capacitance performance after irradiation is due to the oxygen vacancy supported by TRI3DYN simulations. The high charge storage performance of the irradiated samples can be attributed to several factors, including the induced oxygen vacancy and improved surface area. This research adds to the growing body of evidence that ion beam irradiation can be used to fine-tune the supercapacitor electrode's surface area, conductivity, and storage capacity.

Cluster formation by the precise joining of iron oxide nanoparticles on low energy nitrogen ion irradiation

In this work, we have studied low-energy (5 keV) nitrogen ion-induced modification of the surface of iron oxide nanoparticles. The iron oxide nanoparticles were spin-coated on a silicon substrate. The thin films of iron oxide nanoparticles were irradiated at two different ion fluences of 1 × 1016 and 3 × 1016 ions cm−2, respectively. At a fluence of 1 × 1016 ions cm−2, the nanoparticles incline to join with each other forming small clusters which can be attributable due to Ostwald ripening because of the ion-induced defects. At higher fluence of 3 × 1016 ions cm−2, large nanoclusters are formed due to coalescence. We have investigated the morphological and structural properties of both the pristine and altered surface in detail to understand the cluster formation. We anticipate that such reformed surfaces can be beneficial to enhance the surface plasmon resonance.

CALCULATIONS OF THE SPUTTERING YIELD OF SOME ELEMENTS WHEN BOMBARDED WITH NITROGEN IONS

Expanded calculations of the objective sputtering process were completed(Copper, Zinc, Silver, Cesium, Barium) bombarded with nitrogen ions, the calculations were included changing the input parameters for the energy of nitrogen ions and their incidence angle of the target. The program has employed TRIM to perform these calculations. The sputtering yield is directly dependent on these parameters, as changing the incidence angles of the nitrogen ion beam and its energy lead to a tangible change in the output of the perfusion yield. With regard to the target in terms of the thickness of its bombarded layer by proving the parameters of the ions have a direct effect on the atomization yield. The input parameters of the falling ion beam were changed as well as the target to see how they affect the sputtering yield. We found in this study that the best angles of incidence for these ions are when they are close to the angle of 800 and that the higher the energy of the falling ions, the greater the sputtering yield.

Effect of low energy nitrogen ion irradiation on MoO3 films

In the present work, Molybdenum trioxide (MoO3) thin films were deposited by the electrophoretic deposition (EPD) method. Low energy ion irradiation was used to alter the materials properties of MoO3 films. Ion irradiation was carried out at a constant ion fluence of 2.16 x 1016 ions/cm2 for energies varying from 10 keV to 40 keV. The X-ray diffraction (XRD) and Raman spectroscopy revealed the orthorhombic α-MoO3 phase. The optical band gap was observed to change from 3.73 eV to 3.08 eV in a controlled manner due to ion irradiation. Morphology of nanobelt-like structures was seen at the highest energy of ion irradiated films. Atomic force microscopy (AFM) revealed a decrease in the surface roughness with an increase in irradiated ion energy. All results are in corroboration with each other and comprehend the process of tailoring the material properties of MoO3 thin film due to low energy ion irradiation. These tailored properties could be useful for electronic or optical device applications.

Practical and Economical Effects of the Use of Screen Meshes for Steel Nitriding Processes with Glow Plasma

The dynamically developing energy sector forces technologists to create new materials that meet the increasingly higher mechanical, chemical, and electrical requirements. The paper relates to the method of reducing the energy consumption of the plasma nitriding process of austenitic steels. The method proposed by the authors involves the modification of nitriding technology in glow plasma. It consists of introducing perforated screens between the anode and nitrided surface made of a material with a composition similar to the processed material and the use of an HF power supply with controlled mean current generating negative voltage peaks of about 1000 V. Nitriding is carried out in a nitrogen-hydrogen atmosphere. The processed material has a negative potential in relation to the surrounding plasma and strongly negative in relation to the vacuum chamber jacket. The actual treatment is preceded by ionic cleaning of the surface of the detail and heating it to the temperature that activates the diffusion processes. The authors analyse the dynamic distribution of electric fields generated at the surface of the nitrided material with different configurations of the cathode-sample-screen system, trying to find the correlation of treatment parameters with the parameters of the nitrided layer. A significant influence of the screening meshes on the depth of the obtained diffusion layers containing nitrogen was found. The oscilloscopic measurements of the plasma in the boundary layer allowed for the observation of voltage peaks, probably leading to an increase in the peak kinetic energy of nitrogen ions and their easier penetration into the material. The work is of a cognitive nature and is probably one of the first to look for relationships between the dynamic electrical parameters of plasma and the efficiency of nitriding.

Chemical Activity and Morphology of Nanostructured Plasma-Sprayed Titanium Induced by Nitrogen and Argon Ions

The paper focuses on the chemical characteristics of ion-beam passivation effects (of the first-third order) of titanium depending on the dose of implanted ions. The key objective is electron microscopy and SPM-based analysis of nanostructured VT1-00 titanium surfaces produced by entering nitrogen and argon ions of high energy. This type of surfaces can find application in fabrication of devices for the power engineering industry. The obtained experimental data provide evidence of a carbon nanocoating over the surface of titanium implanted with accelerated nitrogen ions, which is similar to that acquired upon titanium implantation with argon ions. A hypothesis is formulated about the existence of a mechanism for changing the chemical activity of titanium as a result of ion-beam nanostructuring – ion-stimulated synthesis of.

Indirect overgrowth as a synthesis route for superior diamond nano sensors

The negatively charged nitrogen-vacancy (hbox {NV}^{-}) center shows excellent spin properties and sensing capabilities on the nanoscale even at room temperature. Shallow implanted hbox {NV}^{-} centers can effectively be protected from surface noise by chemical vapor deposition (CVD) diamond overgrowth, i.e. burying them homogeneously deeper in the crystal. However, the origin of the substantial losses in hbox {NV}^{-} centers after overgrowth remains an open question. Here, we use shallow hbox {NV}^{-} centers to exclude surface etching and identify the passivation reaction of NV to NVH centers during the growth as the most likely reason. Indirect overgrowth featuring low energy (2.5–5 keV) nitrogen ion implantation and CVD diamond growth before the essential annealing step reduces this passivation phenomenon significantly. Furthermore, we find higher nitrogen doses to slow down the NV–NVH conversion kinetics, which gives insight into the sub-surface diffusion of hydrogen in diamond during growth. Finally, nano sensors fabricated by indirect overgrowth combine tremendously enhanced T_2 and T_2^* times with an outstanding degree of depth-confinement which is not possible by implanting with higher energies alone. Our results improve the understanding of CVD diamond overgrowth and pave the way towards reliable and advanced engineering of shallow hbox {NV}^{-} centers for future quantum sensing devices.

Silicon solar cells with nitrogen-rich SiNx/Si interfacial passivation by low-energy nitrogen-ion implantation

We investigated low energy nitrogen ion implantation into the SiNx/Si interfacial layer of silicon solar cells using various energies and fluences, followed by a thermal annealing process. The low energy implanted nitrogen ions penetrated into the SiNx antireflection layer and reached the Si emitter layer. However, ions could not pass through the Ag electrode contact layer and were unable to form the contact passivation layer. A low energy nitrogen ion implanted cell showed the formation of a rich nitrogen layer in the SiNx/Si interfacial area and an increase in electrical performance. With increasing nitrogen ion implantation energy, cells were damaged and suffered decreasing efficiency compared to a reference cell. Increasing the fluence of nitrogen ions also caused a decrease in cell efficiency. After a low temperature annealing process, the cell efficiency recovered almost to the pre-implantation point of the reference cells and showed a similar recovery in their photoreflectance and quantum efficiency. The low-energy nitrogen ion implantation showed the improved cell efficiency of 17.28% for the energy of 12 keV with a fluence of 1 × 1013 cm-2.

(Invited) Novel Synthesis Procedure for Endohedral-Fullerenes Using Laser Ablation Plasma from Solid Material and Vaporized Fullerenes

Since a fullerene was discovered in 1985, fullerene has attracted much attentions [1]. A unique feature of the fullerene that has the spherical structure with hollow interior allows a fullerene to accommodate any other atoms and molecules. Especially, the fullerenes containing other atoms which is called as endohedral fullerene have been expected to be applied in medical uses, electronics systems and so on [2]. In many cases, endohedral fullerenes have been synthesized by ion implantation, co-vaporization of carbon and metal atoms [3], or ion plasma irradiation technique for non-metal material [4]. However, these procedures have remained several issues. One of the critical issues is low production rate for endohedral fullerene synthesize due to difficulties in controlling a physical and a chemical property during synthesizing process. To increase the production efficiency of endohedral fullerene, it is required to optimize elementary process between fullerenes and injected atoms.Under these situations, we recently developed a novel procedure to synthesize endohedral fullerenes that induce the collision of vaporized fullerenes and ablated particles produced by the laser ablation of a solid material. Here, a Q-switched Nd:YAG Laser (Continuum, Powerlite DLS8000) with a wavelength of 1064 nm, a pulse-width of 9 ns, a laser energy of up to 1 J, and a pulse-frequency of up to 10Hz was used. Laser light was focused to be 50 m in diameter on the target surface. In this procedure, N@C60 was synthesized using the ablation of boron nitride material. From the previous studies [4], it is quite important for encapsulated particles to have about 100 eV. Optical emission spectrum of ablated particles by a polychromator (Bunkokeiki, CT-1000) with an intensified CCD detector (Princeton Instruments, PI-Max) was measured, and Doppler shift of the spectrum was estimated. The result showed that the kinetic energy of nitrogen ions was in the range of 20 to 65 eV by controlling the energy of the incident laser beam. The synthesis of N@C60 was conducted with a nitrogen kinetic energy of 65 eV, fullerenes vaporizing temperature of 800 degree Celsius, and a total reaction time of one hour. By optimizing the kinetic energy of ablated particles, synthesis of N@C60 was succeeded [5]. Existence of N@C60 in the toluene solution was confirmed by an electron spin resonance measurement (Elexsys E500, Bruker) without purification by high performance liquid chromatography [6]. The purity of produced N@C60 was two orders of magnitude higher than that achieved using alternative physical synthetic methods that use solid materials, such as arc discharge and co-evaporation methods. However, the purity must be increased by at least two orders of magnitude for the commercial use. Therefore, it is necessary to enhance the purity by optimizing experimental conditions such as laser energy, laser wavelength, amount of ion flux with appropriate energy, repetition rate of laser pulses, laser duration time, area of the laser ablation, and so on. In the meeting, novel synthesis procedure for endohedral-fullerenes using laser ablation plasma from solid material and vaporized fullerenes will be presented.AcknowledgmentsThis study was financially supported by JSPS KAKENHI Grant No. 25287157 from the Ministry of Education, Culture, Sports, Science and Technology of Japan.[1] H. W. Kroto, et.al., Nature 318, 162-163 (1985).[2] H. Shinohara, Rep. Prog. Phys. 63, 843-892 (2000).[3] Alexey A. Popov, et.al., Chem. Rev. 113, 5989-6113 (2013).[4] S.C. Cho, et.al., J. Appl. Phys. 117, 123301 (2015).[5] H. Itagaki, et al., AIP Advances 9-7 (075324), 1-7 (2019).[6] T.A. Murphy, et al., Phys. Rev. Lett. 77-6, 1075 (1996).

Distribution of shallow NV centers in diamond revealed by photoluminescence spectroscopy and nanomachining

We performed nanomachining combined with photoluminescence spectroscopy to understand the depth distribution of nitrogen-vacancy (NV) centers formed by low energy nitrogen ion irradiation of the diamond surface. NV− and NV0 fluorescence signals collected from the surface progressively machined by a diamond tip in an atomic force microscope (AFM) initially rise to a maximum at 5 nm depth before returning to background levels at 10 nm. This maximum corresponds to the defect depth distribution predicted by a SRIM simulation using a 2.5 keV implantation energy per nitrogen atom. Full extinguishing of implantation produced NV− and NV0 zero phonon line peaks occurred beyond 10 nm machining depth, coinciding with the end of easy surface material removal and onset of significant tip wear. The wear ratio of for NV active, ion irradiated diamond compared to the single-crystal diamond tip was surprisingly found to be 22:1. The reported results constitute the first integrated study of in-situ machining and wear characterization via optical properties of the diamond surface containing shallow formed NV centers. We discuss possible metrology applications for diamond tools used in precision manufacturing.

Improvement of graphene scratch resistance by ion beam bombardment

The main aim of the work was investigation of the graphene resistance on mechanical scratch after ion beam bombardment. The CVD graphene on the glass substrate was used. Bombardment of graphene by beams of helium and nitrogen ions of energy 100 keV was applied. Density of ion induced defects in graphene was evaluated using Raman spectroscopy. The polymer indenter was applied for scratch test. Increase of the scratch resistance of the graphene after ion beam bombardment was observed. Scratch resistance of the graphene layer increases with increasing density of defects induced by helium and nitrogen ions. The shape of graphene ribbons exfoliated during scratch test suggests that increase of graphene scratch resistance is accompanied with improvement of graphene adhesion to the substrate. It suggests that ion beam induced defects may be responsible for observed increasing of both graphene scratch resistance ad graphene adhesion to the substrate.

Tunable Wettability and Conductivity of the Graphene Oxide Surface with Insights from Density Functional Theory and Molecular Dynamics Investigations

The current study focuses on the investigation of changes in chemical, wetting, and electrical transport properties of graphene oxide film irradiated by low energy (5 keV) nitrogen ions at differen...

Medium Energy Carbon and Nitrogen Ion Beam Induced Modifications in Charge Transport, Structural and Optical Properties of Ni/Pd/n-GaN Schottky Barrier Diodes.

The irradiation effects of carbon and nitrogen medium energy ions (MEI) on charge transport, structural and optical properties of Ni/Pd/n-GaN Schottky barrier diodes are reported. The devices are exposed to 600 keV C2+ and 650 keV N2+ ions in the fluence range of 1 × 1013 to 1 × 1015 ions cm−2. The SRIM/TRIM simulations provide quantitative estimations of damage created along the trajectories of ion beams in the device profile. The electrical parameters like Schottky barrier height, series resistance of the Ni/Pd/n-GaN Schottky barrier diodes decreases for a fluence of 1 × 1013 ions cm−2 and thereafter increases with an increase in fluence of 600 keV C2+ and 650 keV N2+ ions. The charge transport mechanism is influenced by various current transport mechanisms along with thermionic emission. Photoluminescence studies have demonstrated the presence of yellow luminescence in the pristine samples. It disappears at higher fluences due to the possible occupancy of Ga vacancies. The presence of the green luminescence band may be attributed to the dislocation caused by the combination of gallium vacancy clusters and impurities due to MEI irradiation. Furthermore, X-ray diffraction studies reveal that there is a decrease in the intensity and shift in the diffraction peaks towards the lower side of two thetas. The reductions in the intensity of C2+ ion irradiation is more when compared to N2+ ion irradiation, which may be attributed to change in the mean atomic scattering factor on a given site for light C2+ ion as compared to N2+ ion.

Study of the Surface of Polycrystalline Tin Bombarded with Nitrogen Ions

Abstract—The surface layers of polycrystalline tin are analyzed by Auger electron spectroscopy at temperatures of 293–473 K after being in contact with a nitrogen medium at different pressures and after 100–700-eV nitrogen-ion bombardment. It is established that after nitrogen-ion bombardment, a 389-eV peak appears in the Auger spectra, which is assigned to the nitrogen Auger transition KL2,3L2,3. The dependences of the surface nitrogen concentration on the sample temperature, the bombardment duration, and the energy of nitrogen ions are studied. It is noted that the appearance of nitrogen on the surface of Sn results in a shift of the Sn MNN peaks to lower energies, which indicates the formation of a Sn3N2 film. Argon-ion profiling of the sample surface shows that the thickness of the obtained tin-nitride film is one single layer. From the Auger-analysis data it follows that the film does not decompose up to the melting point of tin.

Epitaxial Growth of Ultrathin δ-Like ΜοΝ Films on Ru(0001)

Growth of ultrathin, single-crystalline, molybdenum-nitride films on Ru(0001) has been investigated by means of X-ray photoelectron spectroscopy (XPS), low energy electron diffraction, and helium ion scattering spectroscopy. The films were prepared in a multistep, sequential process. First, samples were exposed to saturation doses of low kinetic energy nitrogen ions. Second, the samples were exposed to varied doses of molybdenum vapor. Finally, the samples were heated in the renewed presence of low kinetic energy nitrogen ions. Through this process, an annealing temperature of 700 K was found to result in well-ordered, hexagonal films that appear to initially grow layer-by-layer, and in registry with the Ru(0001) support. XPS-characterized chemical-states and relative integrated peak intensities for Mo 3d and N 1s photoelectrons are consistent with those expected for MoN nitride formation. Films annealed above T = 700 K in UHV decompose via a presumptive N2 recombinative desorption mechanism, which leaves the film in a purely metallic Mo–Ru configuration by T = 1100 K.

Low temperature selective growth of GaN single crystals on pre-patterned Si substrates

We report on a hybrid method for fabrication of arrays of GaN nanocrystals by low-temperature UHV selective growth on pre-patterned silicon substrates covered by native oxide. Patterning of the substrates was performed by using a gallium focused ion beam (FIB). To get GaN nanocrystals at specific positions, Ga droplets were created at FIB patterned sites by evaporation of Ga atoms at 280 °C substrate temperature first, and then modified by their post-nitridation using an ultra-low energy (50 eV) nitrogen ion–beam at a sample temperature of 200 °C. To get larger arrays of GaN nanocrystals (≈150 nm and 200 nm in diameter), such a sequential process was repeated in several cycles at slightly modified operation conditions. The quality of the nanocrystals was checked by measurement of their photoluminescence properties which proved the occurrence of the peak of a band edge emission at around 367 nm (3.38 eV).

Effect of nitrogen ion implantation in semi insulating 6H-SiC and recrystallization probed by Raman scattering

The study is intended to investigate the low energy nitrogen ion implantation induced behavior and re-crystallization in semi-insulating 6H-SiC from surface to 5 µm, by Raman spectroscopy. The nature of defects accumulation related to the SiC bond breakages and re-crystallization on vacuum annealing were analyzed from the A1(LO) phonon mode and probed at successive depth from the surface. Variations on the asymmetrical A1(LO) peaks of as-implanted samples were made to order upon annealing, and the mode regained. The peak intensity variation of A1(LO) mode indicated the disorder accumulation. The identified damage depth was in good agreement with Stopping and Ranges of Ions in Matter (SRIM). The changes in Si-Si, deformed-Si-C, C-C vibrations and crystalline-SiC were used to explain the defect role in the implanted and annealed samples.

Analyzing the fractal feature of nickel thin films surfaces modified by low energy nitrogen ion

SummaryFractal concepts are used to explore how different energies (10, 20 and 50 keV) and fluence of 5 × 1017 N+ cm−2 affect the morphology of nickel thin film. The nickel thin film with thickness of 100 nm is prepared by electron beam evaporation technique at room temperature on stainless steel (AISI 316) substrates. The nanoscale three‐dimensional (3‐D) surface micro‐morphologies are investigated by atomic force microscopy (AFM). Interface width is used to describe the surface height fluctuations. The autocorrelation function with height‐height correlation function give the quantitative data about the morphology of surface. The value of roughness exponent and fractal dimension is computed by height‐height correlation function. Fractal measure is an important analysis which provides fundamental insights into the texture characteristics and a direct way of testing their functional role.

Selective area isolation of β-Ga2O3 using multiple energy nitrogen ion implantation

In this study, we report on the application of multiple energy nitrogen ion implantation for the electrical isolation of electronic devices on monoclinic β-Ga2O3. By the introduction of uniformly distributed midgap damage-related levels in the Ga2O3 crystal lattice, we are able to increase the sheet resistances by more than 9 orders of magnitude to ≥1013 Ω/sq which remains stable up to annealing temperatures of 600 °C carried out for 60 s under a nitrogen atmosphere. At higher annealing temperatures, the damage-related trap levels are being removed causing a significant drop of the sheet resistance down to 4 × 105 Ω/sq for annealing temperatures of 800 °C. This effect is preceded by a structural recovery of the implantation damages via the recrystallization of the crystal lattice at already 400 °C as verified by x-ray diffraction measurements. The extracted activation energies of the deep states controlling the high resistivity of Ga2O3 after implantation are in the range of 0.7 eV, showing a strong correlation with the annealing temperature dependence of the sheet resistance and thus supporting the theory of a damage-induced isolation mechanism.