Sputtering Effects Research Articles

Continuous cellular automaton simulation of focused ion beam-induced deposition for nano structures

With the assistance of a gas injection system, focused ion beam-induced deposition (FIBID) can be realized to fabricate complicated three-dimensional structures in nanoscale. The growth rate of the deposited structure depends on the flux of precursor gas and incident ions. In this study, a Continuous Cellular Automaton (CCA) model is put forward to simulate the FIBID process, with four rules established to initiate and dominate the interface evolution, which can calculate the deposited structure profile under different fabrication conditions. In this model, the sputtering and diffusion effects are taken into account to establish a more accurate relationship between the deposition rate and precursor gas flux based on the continuous model, and the influences imposed by precursor gas and incident ions are clarified. In order to verify the precursor gas distribution and the growth mechanism of the FIBID, experiments are carried out with different local precursor gas flux on the substrate surface with a 7 pA and 30 keV Ga ions, using C9H16Pt as the precursor gas. The experimental and simulation results indicate that the CCA model features a high accuracy in predicting the deposited structure profile, and prove that the proposed model can be utilized in fabrication parameters optimization.

Effects of ZnO magnetron sputtering on surface charge and flashover voltage of oil‐impregnated paper

With the aim of exploring an alternative method of nano-doping in cellulose paper and improving flashover strength of oil-impregnated paper, radio frequency (RF) magnetron sputtering method is introduced into the structural modification of insulating paper for converter transformers. In this experiment, insulating paper was treated with ZnO sputtering for 0, 7.5, 15 and 30 min, respectively. The surface morphology of dry paper was observed with a scanning electron microscope. The bonding mode of sputtered ZnO particles with cellulose matrix was investigated via attenuated total reflection infrared (ATR-IR) spectroscopy and mechanical property of the sputtered samples were studied. Surface and volume conductivities of the oil-impregnated sputtered paper were measured. Moreover, the charge dissipation characteristics of sputtered insulating paper was investigated by means of surface potential decay. In addition, trap distribution and carrier mobility of specimen were further obtained. Finally, the DC flashover strength were tested. The results showed that ZnO magnetron sputtering had a distinct influence on the structure of the insulating paper, resulting in the formation of hydrogen bond and chemical bond and an increase of the surface and volume conductivities. ZnO sputtering was found to decrease the initial potential and accelerate charge decay. Moreover, appropriate sputtering enhanced the surface flashover strength.

Characterization of the relationship between neutron production and thermal load on a target material in an accelerator-based boron neutron capture therapy system employing a solid-state Li target.

An accelerator-based boron neutron capture therapy (BNCT) system that employs a solid-state Li target can achieve sufficient neutron flux derived from the 7Li(p,n) reaction. However, neutron production is complicated by the large thermal load expected on the target. The relationship between neutron production and thermal load was examined under various conditions. A target structure for neutron production consists of a Li target and a target basement. Four proton beam profiles were examined to vary the local thermal load on the target structure while maintaining a constant total thermal load. The efficiency of neutron production was evaluated with respect to the total number of protons delivered to the target structure. The target structure was also evaluated by observing its surface after certain numbers of protons were delivered. The yield of the sputtering effect was calculated via a Monte Carlo simulation to investigate whether it caused complications in neutron production. The efficiency of neutron production and the amount of damage done depended on the proton profile. A more focused proton profile resulted in greater damage. The efficiency decreased as the total number of protons delivered to the target structure increased, and the rate of decrease depended on the proton profile. The sputtering effect was not sufficiently large to be a main factor in the reduction in neutron production. The proton beam profile on the target structure was found to be important to the stable operation of the system with a solid-state Li target. The main factor in the rate of reduction in neutron production was found to be the local thermal load induced by proton irradiation of the target.

Influence of Room Temperature Sputtered Al-Doped Zinc Oxide on Passivation Quality in Silicon Heterojunction Solar Cells

Al-doped zinc oxide (AZO) is a potential candidate to substitute tin-doped indium oxide in silicon heterojunction (SHJ) solar cells due to its low cost and low ecological impact. The AZO, sputtered at room temperature (RT), is of particular interest because of low thermal budget and potential for high throughput production with the well-established industrial methods. In SHJ solar cells, high effective carrier lifetime prerequisite for the high open-circuit voltage is achieved with surface passivation by intrinsic amorphous silicon layers followed by doped silicon layers. The passivation quality may be affected by the subsequent sputtering of an AZO layer especially at RT. In this article, we investigated the influence of the AZO sputtering and postdeposition annealing on the effective carrier lifetime in symmetrical silicon layer stacks with n- or p-type doped silicon layers and solar cell precursors. It has been found that the effective carrier lifetime significantly decreased after AZO sputtering at RT. The detrimental effect of AZO sputtering is substrate temperature dependent and is smaller or even absent at elevated temperatures. However, postdeposition annealing, equivalent to the Ag paste curing, mostly recovered the effective carrier lifetime in the symmetrical stacks as well as in the cell precursors. Finally, an aperture area efficiency of 21.2% has been achieved for the 19 mm × 19 mm SHJ solar cell prepared with room temperature sputtered AZO.

A Study on Electromagnetic Harvester with Sputter Coated Cantilever Beam Using Finite Element Analysis

The work is focussed on measuring model parameters of a piezoelectric bending energy harvester cantilever beam with sputter coated technique using finite element analysis. The beam was studied for a wide range of frequencies of about 100-1200Hz. The finite element simulation results confirm that the vibrations in the above mentioned frequency range can be effectively utilised to generate energy. Design of electrometrical vibration energy harvester was carried out with literature survey and the effect was analysed for the given length of beam to the voltage produced by the harvester. The Electromagnetic analysis induced voltage is validated with the help of commercial finite element software ANSYS. The simulation results revealed that the effect of sputter coating on the beam will increase the power generation.

Liquid film behavior and heat-transfer mechanism near the rewetting front in a single rod air–water system

ABSTRACT The rewetting front propagation may occur when the fuel rod is cooled by the liquid film flow after it is dried out under accident conditions for boiling water reactor cores. Our previous study has revealed the importance of precursory cooling, defined as a rapid cooling just before the rewetting, which has a significant effect on the propagation velocity. To understand the mechanism of the precursory cooling, we conducted heat-transfer experiments using a single heater rod contained inside the transparent glass pipe to measure heat-transfer behavior with simultaneous observation using a high-speed camera. The results showed characteristic effects of the wall temperature on the liquid film flow and liquid droplets formation at the rewetting front, i.e. sputtering. Even when the liquid film flows in rivulets under adiabatic condition, horizontally uniformed rewetting front was observed with increasing wall temperature due to enhanced flow resistance by sputtering. This sputtering effect was also confirmed from observations of the liquid film thickness, which increased with approaching the rewetting front. Heat-transfer coefficients were predicted roughly well with a single-phase heat-transfer correlation with entrance effects, suggesting that the thinner thermal boundary layer downstream of the rewetting front may be one of the precursory cooling mechanisms.

The Photoluminescence Spectra Research of SiC Thin Film under Different Sputtering Powers

This study prepared an SiC thin film by using the ratio frequency magnetron sputtering method, investigated the effects of different sputtering powers on the SiC material and analysed the changes in crystal morphology and photoluminescence characteristics caused by changes in the growth conditions used. It was considered that there was 6H-SiC crystal morphologies in the SiC thin film under the experimental conditions prevailing in this study. The SiC morphologies with small grain sizes intermingled and therefore formed anSiC thin film. The analyses of the photoluminescence spectra and Scanning Electron Microscope indicated that the SiC thin film materials with preferable crystal compositions could be prepared under appropriate power inputs.

Effects of Nitrogen Selective Sputtering and Flaking of Nanostructured Coating TiN, TiAlN, TiAlYN, TiCrN, (TiHfZrVNb)N under Helium Ion Irradiation

Effects of Nitrogen Selective Sputtering and Flaking of Nanostructured Coating TiN, TiAlN, TiAlYN, TiCrN, (TiHfZrVNb)N under Helium Ion Irradiation

Determination of Dimension and Conformal Arsenic Doping Profile of a Fin Field Effect Transistors by Time-of-Flight Medium Energy Ion Scattering.

We have developed a methodology that analyzes the dimensions and conformal doping profiles in fin field effect transistors (FinFET) using time-of-flight medium energy ion scattering (TOF-MEIS). The structure of a 3D FinFET and As dopant profiles were determined by comprehensive simulations of TOF-MEIS measurements made in three different scattering geometries. The width and height of a FinFET and the As doping profiles in the top, side, and bottom of fin were analyzed simultaneously. The results showed the dimension and conformal doping profile of nanostructures with complex shape can be determined by TOF-MEIS nondestructively, quantitatively, and with subnm depth resolution without any sputtering and matrix effects.

Effects of argon ion sputtering on the surface of graphene/polyethylene composites

Argon ion sputtering at various energies in the range of 500–5000 eV is performed on polymer composites of ultra-high molecular weight polyethylene (UHMWPE) with 4.6 wt% graphene nanoplatelets (GNPs). X-ray photoelectron spectroscopy (XPS) shows that irradiation above 3000 eV causes an abrupt transition from tetrahedral sp3 into planar sp2 carbon in the blank polyethylene surface. This graphitization process, as well as the formation of certain oxygen groups after the subsequent exposure to air, is delayed by graphene in the composites. Besides, both XPS and Raman spectroscopy indicate that a part of the sp2 graphene network is transformed into sp3 carbon defects by irradiation. Surface hardness and Young's modulus increase by 30–100% in blank polyethylene and the composites upon irradiation. The surface electrical resistance of polyethylene decreases from 1015 to 108 Ω by sputtering at 5000 eV. Composites that are consolidated at low temperature (175 °C) experience a transition from insulating (1015 Ω) to conducting (104 Ω) in a narrow range of Ar+ sputtering energies, while for a high consolidation temperature (240 °C) the transition is not observed. This research provides information on the induced interaction mechanisms between graphene and a polymer matrix upon ion beam irradiation.

Effects of gas cluster ion beam sputtering on the molecular orientation of organic semiconductor films: Ultraviolet photoelectron spectroscopy study of [6]phenacene

The alignment of organic layer and metal layer energy levels within organic semiconductor devices is critical for efficient charge injection/collection at the electrodes. The electronic structure at the interface is usually examined using ultraviolet photoelectron spectroscopy (UPS) as the film thickness of the organic layer is built up incrementally (bottom-up method). As such, the morphology and crystallinity of the films that are examined using this technique may be different from the films used in actual devices because these properties are sensitive to the way in which the films are prepared. We have prepared [6]phenacene thin films with standing and lying molecular orientations on naturally oxidized silicon (SiO2) and highly oriented pyrolytic graphite (HOPG) surfaces, respectively. UPS measurements were performed on films that were incrementally decreased in thickness using gas cluster ion beam (GCIB) sputtering (top-down method). The spectral shapes and ionization energies of the films that were formed using the bottom-up and top-down methods were similar. Importantly, the characteristic features of a monolayer on the HOPG substrate were also observed when a thick film (i.e., not built up in layers using the bottom-up method) was thinned down by GCIB sputtering. We have shown that UPS combined with GCIB sputtering is a useful technique for examining the energy level alignment of interfaces within films that are fabricated using conditions similar to those used for real devices.

INFLUENCE OF ARGON PRESSURE ON MICROSTRUCTURE AND OPTICAL PROPERTIES OF Zn0.9Se:Co0.1 THIN FILMS PREPARED BY PULSED LASER DEPOSITION

Zn[Formula: see text]Se:Co[Formula: see text] thin films were deposited on sapphire (Al2O3) substrates in argon atmosphere at various gas pressures by pulsed laser deposition. Influence of argon pressure on the thickness, surface morphology, crystal structure and optical properties of the thin films were investigated by various diagnosis tools. It was found that these physical properties were correlated to the argon pressure and appeared like a mutation between the pressure of 2[Formula: see text]Pa and 4[Formula: see text]Pa. As the deposition pressure changed from 2[Formula: see text]Pa to 4[Formula: see text]Pa, the collision probability between ablated species and argon molecule was increased, which resulted in the transformation of the deposition type from sputter effect to adsorption effect and the mutation of film thickness and structure. These in turn influence the transmission range and band gap of the films. All of the results suggest that the ambient pressure is a very important factor to the deposition of Zn[Formula: see text]Se:Co[Formula: see text] films by PLD.

Perovskite–Ion Beam Interactions: Toward Controllable Light Emission and Lasing

Achieving controllable coherent and incoherent light sources is crucial to meet the requests of the constantly developing integrated optics, which, however, remains challenging for the existing semiconductor materials and techniques. All-inorganic lead halide perovskites (ILHPs) are emerging as the promising semiconductors, featuring the defect-tolerant nature and tunable band gap. Herein, an experimental design, based on the interaction between ILHPs and energetic ions, for achieving controllable light emitters and microlasers is reported. We reveal that the photoluminescence intensity from ILHPs can be modulated by more than 1 order of magnitude upon low-dose gallium ion (∼1015 ions/cm2) irradiation, which can be attributed to the generation of vacancy/interstitial defects, metallic lead, and crystal-to-amorphization transition. Such ion-dependent light emission can be exploited to make the colorful photopatterns and in situ tailor the lasing behavior from CsPbBr3 microplates. Further, a strong sputtering effect is observed with the increase of the ion dose (∼1017 ions/cm2), which enables the top-down fabrication of microlasers based on ILHPs. These findings represent a significant step toward controllable light sources leveraging on perovskite-ion interactions.

Sputtering distribution of LIPS200 ion thruster plume

This paper investigates the sputtering distribution of LIPS200 ion thruster plume. Considering the ground test results cannot fully represent the on-orbit status, computer simulation is highly needed to study the sputtering distribution on orbit. To ensure the credibility of simulation results, the experimental and simulation analysis in the ground test conditions were performed. After verification of the experimental results, we carried out the simulation analysis in on-orbit condition (vacuum condition). The results show that, within the off-axis angle of 70° (deg), the sputtering distribution in the ground test condition is basically the same as that in vacuum condition, and the main particles causing sputtering are Xe+ and Xe2+. In the region of the off-axis angle greater than 70 deg, the sputtering result in vacuum condition is obviously lower than that in the ground test condition, and the sputtering effect is mainly caused by the charge-exchange (CEX) ions. The CEX ions in the ground test condition and vacuum condition show the “jet like” and the “mushroom like” distributions respectively. This work verifies the feasibility of the hybrid Particle-in-Cell and Direct Simulation Monte Carlo (PIC DSMC) simulation method as well as the sputtering model to predict the space sputtering effect which can be introduced as a reference for the design of electric propulsion spacecraft.

Research on the Surface Evolution of Single Crystal Silicon Mirror Contaminated by Metallic Elements during Elastic Jet Polishing Techniques.

Metallic elements can contaminate single crystal silicon mirror during ion beam etching (IBE) and other postprocessing methods, which can affect the performance of components in an infrared laser system. In this work, scanning electron microscope (SEM) and atomic force microscope (AFM) were used to characterize the distribution of contaminant represented by aluminum (Al). After characterizing contaminated area, elastic jet polishing (EJP), EJP, and static alkaline etching (SAE) combined technique were used to process the mirror. The morphology and laser-induced absorption were measured. Results show that metallic elements can mix with silicon and generate bulges due to the sputtering effect. In addition, SAE and EJP combined technique can remove metallic contaminant and stabilize the surface quality. Research results can be a reference on conducting postprocessing technologies to improve laser damage resistance property of single crystal silicon mirror in infrared laser system.

Preferential sputtering effects in depth profiling of multilayers with SIMS, XPS and AES

Multilayer profiles are studied using the MRI model with extension to preferential sputtering. The results show a clear distinction with respect to the main contributions to the depth resolution, namely surface and interface roughness, and atomic mixing. For dominating roughness, the effect of preferential sputtering is more pronounced for the residual surface composition profile (detected by XPS and AES), but it is zero for the sputtered matter composition profile (detected by SIMS). Dominating mixing results in a strong effect of preferential sputtering on the shape of the profile. While in that case its effect on the XPS or AES depth profile is relatively moderate, its effect on the SIMS depth profile is surprisingly strong and appears to be in contradiction to textbook statements. Interface width, location and layer thickness are always affected by preferential sputtering in XPS and AES depth profiles, but SIMS depth profiles are only affected if the contribution of atomic mixing to depth resolution cannot be ignored. In conclusion, a new definition of multilayer resolution is proposed which is based on the normalized amplitude of the wave-like profiles. The successful application of MRI model extended for preferential sputtering is given for fitting an experimental AES depth profile of an Ag/Ni multilayer.

Recovering in-plane six-fold magnetic symmetry of epitaxial Fe films by N<sup>+</sup> implantation

In order to study the effect of ion implantation on the in-plane magnetic anisotropy of epitaxial magnetic films, a 3-nm Al buffer layer is epitaxially grown on an Si (111) substrate with a miscut angle, and then 25-nm Fe is grown on the buffer layer. High-resolution X-ray diffraction reveals that the epitaxial Fe film has a (111)-oriented bcc structure. The epitaxial Fe films are implanted by 10 keV N<sup>+</sup> ions with dose up to 5 × 10<sup>16</sup> ions/cm<sup>2</sup>. The change and mechanism of the in-plane magnetic anisotropy of the epitaxial Fe film are studied systematically. It is found that the in-plane magnetic anisotropy of the epitaxial Fe film is gradually changed from two-fold to six-fold symmetry with the increase of N<sup>+</sup> implantation dose. It is confirmed by transmission electron microscopy and etching experiments that ion implantation changes the surface and interface state of Fe film. This result is consistent with the result from the SRIM software simulation. The in-plane magnetic uniaxial anisotropy of epitaxial Fe film comes from atomic steps at the surface and the interface of the Fe film. These steps result from Si (111) substrate with a miscut angle. Ion implantation has effects on sputtering and atomic diffusion. The sputtering effect causes the step at the surface of the Fe film to be erased, and the diffusion of the atom leads the step at the interface of the Fe film to disappear. The in-plane uniaxial anisotropy induced by the atomic step is weakened, and the magnetocrystalline anisotropy induced by the Fe (111) plane is dominant. Therefore, the epitaxial Fe film exhibits Fe (111) plane induced six-fold magnetic symmetry after high-dose N<sup>+</sup> implantation. This work indicates that the in-plane magnetic anisotropy of Fe films epitaxially grown on Si (111) substrate with miscut angle can be modified and precisely controlled by ion implantation. This work may be of practical significance for improving the density of in-plane magnetic recording material.

Effects of sputtering deposited homoseed layer microstructures on crystal growth behavior and photoactivity of chemical route-derived WO3 nanorods

The crystal growth properties of hydrothermally derived WO3 nanorods were investigated using various WO3 thin-film seed layers.

High Ferroelectricities and High Curie Temperature of BiInO3PbTiO3 Thin Films Deposited by RF Magnetron Sputtering Method☆☆Supported by the National Natural Science Foundation of China under Grant No 11304160, the Special Fund for Public Interest of China under Grant No 201510068, and the NUPTFC under Grant No NY215111.

Properties of ferroelectric xBiInO3-(1 − x)PbTiO3 (xBI-(1 − x)PT) thin films deposited on (101) SrRuO3/(200) Pt/(200) MgO substrates by rf magnetron sputtering method and effects of deposition conditions are investigated. The structures of the xBI-(1 − x)PT films are characterized by x-ray diffraction and scanning electron microscopy. The results indicate that the thin films are grown with mainly (001) orientation. The chemical compositions of the films are analyzed by scanning electron probe and the results indicate that the loss phenomena of Pb and Bi elements depend on the pressure and temperature during the sputtering process. The sputtering parameters including target composition, substrate temperature, and gas pressure are adjusted to obtain optimum sputtering conditions. To decrease leakage currents, 2 mol% La2O3 is doped in the targets. The P–E hysteresis loops show that the optimized xBI-(1 − x)PT (x = 0.24) film has high ferroelectricities with remnant polarization and coercive electric field . The Curie temperature is about 640 °C. The results show that the films have optimum performance and will have wide applications.

Influence of magnetron sputtering on composition of spherical gas discharge plasma

The effect of magnetron sputtering of an electrode on the chemical composition of a plasma of a spherical gas discharge is studied experimentally by mass spectrometry. The experiments were carried out in an apparatus for studying plasmochemical processes in a gas discharge of spherical geometry with a small anode. It was revealed that in the argon discharge, the molecules of the electrodes of both the vacuum chamber and the target of the magnetron are detected by mass spectrometry. It is not observed in the case of a spherically stratified gas discharge in ethanol which is explained by the confinement of molecules in the potential wells of the striations.