Ar Ion Beam Research Articles

Combined Surface-Activated Bonding Technique for Low-Temperature Cu/SiO2 Hybrid Bonding

This work develops a combined surface-activated bonding (SAB) technique for low-temperature SiO2-SiO2 and Cu-Cu bonding at 200 °C. The combined SAB technique involves combinations of surface activation by using surface bombardment by neutralized Ar ion beam containing Si atoms, water vapor exposure, and prebonding attach/detach prior to wafer bonding in vacuum. Bonding strength close to Si bulk fracture energy was achieved for both SiO2-SiO2 and Cu-Cu bonding pairs. We suggest the enhanced –OH (both Si–OH and Cu–OH) chemisorption on the wafers and pre-bonding removal of excess H2O from the interface/surfaces are the key factors involved in the present low-temperature bonding technique. This technique is promising for 3D integration through Cu/SiO2 hybrid bonding at no more than 200 °C.

Ar Implantation at the hBN/Rh(111) Nanomesh by ab Initio Molecular Dynamics

The controlled intercalation of selected species underneath graphene or hexagonal boron nitride (hBN) on a substrate opens new ways for the functionalization and the tuning of properties of these systems. In this work, the case of hBN on rhodium exposed to a low-energy Ar-ion beam [Cun et al., Nano Lett. 2013, 13, 2098–2103] is further considered theoretically. With the help of ab initio molecular dynamics, the structural rearrangements induced by the interaction between the impacting Ar ion and the substrate are investigated. It is shown that the ion can be intercalated and trapped between the metal and hBN by breaking some BN bonds and penetrating the overlayer. The resulting defective structure relaxes quickly, while Ar moves to a stable site where a protrusion appears on top of the characteristic super honeycomb lattice of the nanomesh. The presented results provide a first atomistic description of the complex processes leading to the formation of the, so-called, boron nitride nanotents.

Is organic pore development in gas shales influenced by the primary porosity and structure of thermally immature organic matter?

Organic matter (OM)-hosted pores, rather than mineral-hosted pores, are considered to be the dominant contributors to total porosity and hydrocarbon storage in many organic-rich unconventional reservoirs. OM-hosted pores are thought to develop during thermal maturation as generated hydrocarbons are expelled from the kerogen, leaving behind pores. However, prediction of OM-hosted pore development is hampered by the lack of a simple relationship between thermal maturity and OM-hosted porosity, with the controls on pore distribution, size and morphology remaining poorly known. In particular, the extent to which thermally immature OM hosts primary pores and the influence that these have on subsequent organic pore development remains poorly understood. Here we employ Ar ion beam polishing and high resolution scanning electron microscopy to show that primary OM-hosted pores are common in thermally immature shales of varying ages and depositional settings, where they occur in both structured and amorphous OM. We further find, utilising a thermal maturity gradient in the Devonian-Mississippian Woodford Shale, that although OM-hosted pores are common in the least mature (<0.4%Ro) samples imaged they are not evident in examples that are mature (0.5–1.1%Ro). However, OM-hosted pores similar to those observed in the least mature samples are present in gas-mature samples (⩾1.5%Ro), where they are classified as secondary pores. Solvent extraction to remove bitumen from oil-mature samples results in an abundance of pores in samples where previously none were evident, which suggests that the absence of primary OM-hosted pores in untreated oil-mature samples is due to infilling of pores by generated and retained bitumen. The similar size and morphology of more complex secondary pores and primary pores is consistent with re-emergence of primary pores in gas-mature structured organic matter, following expulsion of infilling bitumen. Inheritance of pore structure is less evident in amorphous OM types, where secondary pores exhibit a distinctive spherical morphology that has previously been attributed to a gas bubble origin within bitumen. However, similar spherical pore morphologies are evident in immature amorphous OM, arguing against a maturation related origin, so that re-emergence of primary pores cannot be ruled out. Our findings are also relevant to models of hydrocarbon storage and migration. Given that bitumen filled organic pores are likely open in regards to hydrocarbon migration, the importance of organic pore networks for primary migration in the oil window may have been underestimated – well developed organic pore networks contributing to permeability and storage capacity are otherwise assumed to be a feature characteristic of gas-mature shale reservoirs.

In-situ XMCD evaluation of ferromagnetic state at FeRh thin film surface induced by 1 keV Ar ion beam irradiation and annealing

Surface ferromagnetic state of FeRh thin films irradiated with 1keV Ar ion-beam has been investigated by using soft X-ray Magnetic Circular Dichroism (XMCD). It was revealed that the Fe atoms of the samples were strongly spin-polarized after Ar ion-beam irradiation. Due to its small penetration depth, 1keV Ar ion-beam irradiation can modify the magnetic state at subsurface of the samples. In accordance with the XMCD sum rule analysis, the main component of the irradiation induced ferromagnetism at the FeRh film surface was to be effective spin magnetic moment, and not to be orbital moment. We also confirmed that the surface ferromagnetic state could be produced by thermal annealing of the excessively ion irradiated paramagnetic subsurface of the FeRh thin films. This novel magnetic modification technique by using ion irradiation and subsequent annealing can be a potential tool to control the surface magnetic state of FeRh thin films.

Room temperature superparamagnetism in rutile TiO2 quantum dots produced via ECR sputtering

Nanostructures (NS) have been fabricated on rutile TiO2(110) single crystal surfaces using Ar ion beam sputtering technique. Pronounced quantum confinement effects in TiO2 nanodots lead to reduction in optical reflectance and bandgap widening. Moreover, a direct correlation between the size of NS and magnetic behavior is observed. This suggests that the size of NS plays crucial role in the evolution of magnetic nature. Though the smallest (∼5nm) NS display superparamagnetic (SPM) behavior, ferromagnetism is observed for larger nanostructures. Single domain nature of TiO2 quantum dots is responsible for the observed SPM behavior.

Room Temperate Bonding of Al2O3 Layers by Atomic Layer Deposition on Polyimide Substrates

Atomic layer deposition (ALD) gas barrier layer coatings on polymer substrates have been studied to address the problem of short-lifetime of polymer devices. ALD Al2O3 layers deposited with trimethylaluminium (TMA) and H2O vapor precursors are relatively dense and conformal, so ALD Al2O3 layers are good candidates for effective gas barriers against water vapor and oxygen permeation. In order to seal such ALD Al2O3 coated polymer substrates without organic adhesives, the bonding technique of choice has to satisfy low temperature bonding requirements. Utilizing a high temperature bonding process would damage thermally sensitive polymer substrates during thermal compression bonding. Furthermore the gas barrier property of organic adhesives would be too low for effective sealing. The polymer substrates used in this study are polyimide (PI) sheets from XENOMAX® from Toyobo Co., Ltd that are widely used as substrates for flexible electronics. These polyimide sheets have extremely smooth surfaces (RMS ~1 nm), which are conducive for bonding, because good large contact areas can be obtained. These polyimide substrate sheets of 35 μm thickness were coated with Al2O3 films of 250 ALD cycles using different process temperatures ranging from 80 ºC, 150 ºC and 250 ºC, while 100 ALD cycles were used at 250 ºC. The warpage of the polyimide sheets, the surface morphology, and the results of bonding for these ALD Al2O3 coated polyimide samples were investigated as a function of different ALD deposition temperatures. The polyimide sample processed at the higher ALD Al2O3 temperature of 250 ºC exhibited much larger warpage, which is detrimental for bonding. We prepared PI sheets whose size was 10 cm x 10 cm. The ALD Al2O3 on polyimide samples deposited at 80, 150, and 250 ºC display warpage, and these edges lifted up to 1 mm, 3 mm, and 5 mm from a horizontal plane, respectively. This warpage is attributed to the difference of thermal expansion coefficients between the polyimide sheet and the deposited ALD Al2O3 layer. The surface morphology of the ALD layer was studied using atomic force microscopy (AFM) surface profiling. The sample deposited at a lower ALD temperature has smoother surface morphologies. Our ALD Al2O3 films synthesized at 80 ºC exhibited a very smooth surface morphology indicative of amorphous material, while the Al2O3 film synthesized at 250 ºC was observed to possess a granular structure demonstrating recrystallization into a polycrystalline film. The rough grain structure of ALD Al2O3 films deposited at 250 ºC exceeds the critical surface roughness and as a consequence prevents surfaces from bonding. For the bonding experiment, all PI samples coated by ALD Al2O3 were bonded using a modified method of Surface Activated Bonding (SAB) employing a nano-adhesion layer. First, ALD Al2O3 layers of about 25 nm are deposited on the surface of the polyimide substrates using trimethylaluminium (TMA) and water as precursors. Next, the Al2O3-coated surfaces are moved inside a high vacuum bonding machine and cleaned using Ar-ion beam bombardment. After the surface cleaning process step, Si nano-adhesive layers are deposited via ion-beam sputtering. Subsequently, the surface of the nano-adhesion layers are activated using the Ar-ion beam SAB method. Finally, surfaces were brought into close contact and bonded under compression in ultra-high vacuum. The structure of the bond interface was PI/Al2O3/Si/Si/Al2O3/PI. Here the thickness of each ALD Al2O3 layer and Si layer are 25 nm and 10 nm, respectively. We compared the results of the bonding of PI films coated at different ALD process temperatures. All bonding processes were performed at room temperature in ultra high vacuum. While the ALD Al2O3 samples deposited at 150 ºC suffered various non-bonded areas due to warpage and surface roughness, the ALD films deposited at 80 ºC revealed near perfect bonding without any voids, which is desirable for tight sealing of gas barrier layers. Room temperature bonding of ALD Al2O3 films on Si and polyimide substrates was successfully performed. Due to high temperature gradient induced warpage of the polymer substrate and elevated surface roughness of the ALD layer, a lower process temperature of 80 ºC for ALD synthesis of Al2O3 provided optimum gas barrier conditions. The results of our bonding experiments demonstrate that larger bonded areas were achieved when the ALD synthesis of Al2O3 gas barrier layers was performed at 80 ºC. This bonding method is expected to be used for future microelectronics packaging and gas barrier sealing for polymer substrate.

Surface wet-ability modification of thin PECVD silicon nitride layers by 40 keV argon ion treatments

Abstract Measurements of wet-ability of liquid drops have been performed on a 30 nm silicon nitride (Si3N4) film deposited by a PECVD reactor on a silicon wafer and implanted by 40 keV argon ions at different doses. Surface treatments by using Ar ion beams have been employed to modify the wet-ability. The chemical composition of the first Si3N4 monolayer was investigated by means of X-ray Photoelectron Spectroscopy (XPS). The surface morphology was tested by Atomic Force Microscopy (AFM). Results put in evidence the best implantation conditions for silicon nitride to increase or to reduce the wet-ability of the biological liquid. This permits to improve the biocompatibility and functionality of Si3N4. In particular experimental results show that argon ion bombardment increases the contact angle, enhances the oxygen content and increases the surface roughness.

Quantitative imaging of trace B in Si and SiO2 using ToF-SIMS

Changes in the oxidation state of an element can result in significant changes in the ionization efficiency and hence signal intensity during secondary ion mass spectrometry (SIMS) analysis; this is referred to as the SIMS matrix effect [Secondary Ion Mass Spectrometry: A Practical Handbook for Depth Profiling and Bulk Impurity Analysis, edited by R. G. Wilson, F. A. Stevie, and C. W. Magee (Wiley, New York, 1990)]. The SIMS matrix effect complicates quantitative analysis. Quantification of SIMS data requires the determination of relative sensitivity factors (RSFs), which can be used to convert the as measured intensity into concentration units [Secondary Ion Mass Spectrometry: A Practical Handbook for Depth Profiling and Bulk Impurity Analysis, edited by R. G. Wilson, F. A. Stevie, and C. W. Magee (Wiley, New York, 1990)]. In this manuscript, the authors report both: RSFs which were determined for quantification of B in Si and SiO2 matrices using a dual beam time of flight secondary ion mass spectrometry (ToF-SIMS) instrument and the protocol they are using to provide quantitative ToF-SIMS images and line scan traces. The authors also compare RSF values that were determined using oxygen and Ar ion beams for erosion, discuss the problems that can be encountered when bulk calibration samples are used to determine RSFs, and remind the reader that errors in molecular details of the matrix (density, volume, etc.) that are used to convert from atoms/cm3 to other concentration units will propagate into errors in the determined concentrations.

Morphology Study of Si Surface Topography Irradiated by Ar Ion Beam Sputtering

In this paper, Si crystal (000) surface was bombarded by Ar ion beam, with the energy of 90 KeV and the irradiating time of 10 min. In the process of irradiation, there were bulges on the surface of Si crystal surface, the highest of which reached 100 nm. The information of roughness (such as change in level, angle and etc.) were studied by AFM, TEM, SEM and Raman.

Native Defects And Optical Properties Of Ar Ion Irradiated ZnO

MeV Argon (Ar) ion irradiation turns white coloured ZnO to yellowish (fluence 1 × 10 14 ions/cm 2 ) and then reddish brown (1 × 10 16 ions/cm 2 ). At the same time the material becomes much more conducting and purely blue luminescent for the highest fluence of irradiation. To get insight on the defects in the irradiated samples Ultraviolet-visible (UV-vis) absorption, Raman, and photoluminescence (PL) spectroscopy and Glancing Angle X-Ray Diffraction (GAXRD) measurements have been carried out. Enhancement of overall disorder in the irradiated samples is reflected from the GAXRD peak broadening. UV-vis absorption spectra of the samples shows new absorption bands due to irradiation. Complete absorption in the blue region of the spectrum and partial absorption in the green and red region changes the sample colour from white to reddish brown. The Raman peak representing wurtzite structure of the ZnO material (~ 437 cm -1 ) has decreased monotonically with the increase of irradiation fluence. At the same time, evolution of the 575 cm -1 Raman mode in the irradiated samples shows the increase of oxygen deficient disorder like zinc interstitials (IZn) and/or oxygen vacancies (VO) in ZnO. PL spectrum of the yellow coloured sample shows large reduction of overall luminescence compared to the unirradiated one. Further increase of fluence causes an increase of luminescence in the blue region of the spectrum. The blue-violet emission can be associated with the interstitial Zn (IZn) related optical transition. The results altogether indicates IZn type defects in the highest fluence irradiated sample. Large changes in the electrical resistance and luminescent features of ZnO using Ar ion beam provides a purposeful way to tune the optoelectronic properties of ZnO based devices. Copyright © 2015 VBRI press.

The development of a room temperature electron cyclotron resonance ion source (Lanzhou electron cyclotron resonance ion source No. 4) with evaporative cooling technology at Institute of Modern Physics.

LECR4 (Lanzhou electron cyclotron resonance ion source No. 4) has been successfully constructed at IMP and has also been connected with the Low Energy Beam Transport (LEBT) and Radio Frequency Quadrupole (RFQ) systems. These source magnet coils are cooled through evaporative cooling technology, which is the first attempt with an ECR ion source in the world. The maximum mirror field is 2.5 T (with iron plug) and the effective plasma chamber volume is 1.2 l. It was designed to be operated at 18 GHz and aimed to produce intense multiple charge state heavy ion beams for the linear injector project SSC-Linac at IMP. In February 2014, the first analyzed beam at 18 GHz was extracted. During about three months' commissioning, some outstanding results have been achieved, such as 1.97 emA of O(6+), 1.7 emA of Ar(8+), 1.07 emA of Ar(9+), and 118 euA of Bi(28+). The source has also successfully delivered O(5+) and Ar(8+) ion beams for RFQ commissioning in April 2014. This paper will give a brief overview of the design of LECR4. Then, the latest results of this source at 18 GHz will be presented.

Comprehensive identification of mutations induced by heavy-ion beam irradiation in Arabidopsis thaliana.

Heavy-ion beams are widely used for mutation breeding and molecular biology. Although the mutagenic effects of heavy-ion beam irradiation have been characterized by sequence analysis of some restricted chromosomal regions or loci, there have been no evaluations at the whole-genome level or of the detailed genomic rearrangements in the mutant genomes. In this study, using array comparative genomic hybridization (array-CGH) and resequencing, we comprehensively characterized the mutations in Arabidopsis thaliana genomes irradiated with Ar or Fe ions. We subsequently used this information to investigate the mutagenic effects of the heavy-ion beams. Array-CGH demonstrated that the average number of deleted areas per genome were 1.9 and 3.7 following Ar-ion and Fe-ion irradiation, respectively, with deletion sizes ranging from 149 to 602,180 bp; 81% of the deletions were accompanied by genomic rearrangements. To provide a further detailed analysis, the genomes of the mutants induced by Ar-ion beam irradiation were resequenced, and total mutations, including base substitutions, duplications, in/dels, inversions, and translocations, were detected using three algorithms. All three resequenced mutants had genomic rearrangements. Of the 22 DNA fragments that contributed to the rearrangements, 19 fragments were responsible for the intrachromosomal rearrangements, and multiple rearrangements were formed in the localized regions of the chromosomes. The interchromosomal rearrangements were detected in the multiply rearranged regions. These results indicate that the heavy-ion beams led to clustered DNA damage in the chromosome, and that they have great potential to induce complicated intrachromosomal rearrangements. Heavy-ion beams will prove useful as unique mutagens for plant breeding and the establishment of mutant lines.

Exploring the Structure of the Modified Top Layer of Polypropylene During Plasma Treatment

Plasma modifications of polypropylene (PP) surfaces are analyzed by means of vacuum beam experiments. A plasma source provides Ar ion beams and a background of UV photons. Additionally, neutral oxygen beams are sent to perform reactive sputtering of PP. The etch rate and chemical state are monitored in real time by in situ Fourier transform infrared (FTIR) spectroscopy. At the onset of Ar bombardment, PP shows high sputter yields, which decrease down to a constant etch rate indicating the formation of a modified top layer. The stationary top layer is modeled as combination of a pristine fraction plus a cross‐linked fraction of amorphous hydrocarbon. Photon‐ and ion‐dominated etch processes provide different cross‐linking fractions, whereas the sputter efficiency is maximized at intermediate ion energies (200 eV).

Application of Ion Beam Induced Chemical Vapor Deposition for SiC Film Formation on Si Substrates using Methylsilane

We propose an experimental methodology for producing silicon carbide (SiC) films on Si substrates using an ion beam induced chemical vapor deposition (IBICVD) technique with methylsilane (SiH3CH3) as a gas source. Both methylsilane gas (1.2 sccm) and Ar ion beam (100 eV, 5μA) were simultaneously introduced onto Si(100) substrates. Temperatures of Si substrates were set at 600, 700, or 800°C. A SiC thin film was formed by the simultaneous introduction of methylsilane and Ar ions onto the Si substrate when the substrate temperature was 600°C. On the other hand, in the cases of 700 and 800°C, SiC films were formed by methylsilane gas alone and SiC film deposition rates by methylsilane gas with the Ar ion beam were approximately identical with those obtained without the Ar ion beam. We therefore conclude that the IBICVD technique with methylsilane is useful for SiC film formation on Si at relatively low substrate temperatures. [DOI: 10.1380/ejssnt.2015.174]

High speed micro-fabrication using inductively coupled plasma ion source based focused ion beam system

A compact inductively coupled plasma ion source based focused ion beam system (ICP-FIB), capable of producing intense FIB of gaseous elements is developed. Ar and Xe ion beams of 20–4700 nA are focused to spot sizes in the range of 2–30 μm. Experiments using Ar and Xe ion beams of a few microamperes showed milling speeds that are 25–150 times higher than that of a conventional FIB. Milling of micro-apertures in less than 100 s through 100 μm thick Ta and Mo foils and in less than 10 s through 12 μm gold and 25 μm aluminum foils is demonstrated. In this article, the potential of ICP-FIB in high speed milling of micro apertures and large scale micro patterns are presented. Also the possibility of high speed synthesis of nano-pores with tunable pore sizes is discussed.

Graphene nanodots-encaged porous gold electrode fabricated via ion beam sputtering deposition for electrochemical analysis of heavy metal ions

A graphene nanodots-encaged porous gold electrode via ion beam sputtering deposition (IBSD) for electrochemical sensing is presented. The electrodes were fabricated using Au target, and a composite target of Al and graphene, which were simultaneously sputtered onto glass substrates by Ar ion beam, followed with hydrochloric acid corrosion. The as-prepared graphene nanodots-encaged porous gold electrodes were then used for the analysis of heavy metal ions, e.g. Cu2+ and Pb2+ by Osteryoung square wave voltammetry (OSWV). These porous electrodes exhibited enhanced detection range for the heavy metal ions due to the entrapped graphene nanodots in 3-D porous structure. In addition, it was also found that when the thickness of porous electrode reached 40nm the detection sensitivity came into saturation. The linear detection range is 0.009–4μM for Cu2+ and 0.006–2.5μM for Pb2+. Good reusability and repeatability were also observed. The formation mechanism and 3-D structure of the porous electrode were also investigated using scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectra (XPS). This graphene entrapped 3-D porous structure may envision promising applications in sensing devices.

Depth profiling organic light-emitting devices by gas-cluster ion beam sputtering and X-ray photoelectron spectroscopy

The composition depth profile in organic light-emitting devices (OLEDs) is investigated using X-ray photoelectron spectroscopy (XPS) coupled with gas-cluster Ar-ion beam milling (Ar-GCIB). The XPS technique gives precise information about the surface chemistry of the organic thin films and is capable of differentiating the various charge transport, host and guest materials used in an OLED. The use of large Ar ion clusters (∼1500–2500atoms/cluster) in the milling process allows for small amounts of the organic thin film to be sputtered away without contaminating the surface or damaging the underlying material chemistry. By probing OLEDs as a function of depth, key parameters including emissive layer composition and interface quality can be assessed directly. It is found that the depth profile for graded-composition emissive layer OLEDs closely matches the intended deposition profiles, maintaining both the composition gradient and the intended endpoint compositions. The ability to resolve and correlate subtle changes in film composition to variations in device performance will help inform efforts in device design, while also serving as a diagnostic tool to better understand the mechanisms for device degradation and failure.

Contact Behavior among Vertical Aligned Carbon Nanotube Bumps under Compression for Flexible Multilayer Substrates

Carbon nanotubes (CNTs) are expected to be a substitutional wiring material instead of copper, because of the properties of high maximum allowable current density, and the low resistivity. Especially, bundled vertically aligned CNTs (VA-CNTs) have the flexible structure and it is considered that VA-CNTs are suitable for vertical interconnect among flexible substrates.In this research, we fabricated VA-CNTs as bump shaped structures and located on flexible substrates for flexible multilayer substrates and their electrical property was investigated.At first, VA-CNT bumps were synthesized on SOI substrate by the thermal chemical vapor deposition method using Fe as catalyst and acetylene gas as source gas. Secondly, Au was sputtered on the substrate of VA-CNT bumps by magnetron sputter. In this process, surface shells of top of VA-CNT were torn by plasma energy and sputtered Au particle was directly contacted to the edges of torn layer of VA-CNTs and inner layers of CNTs for low contact resistance. Subsequently, the substrate of VA-CNT bumps was bonded to Au electrodes on polyimide substrate by surface activated bonding method, that surfaces of specimens were cleaned and activated by Ar ion beam or Ar plasma in vacuum, then they were bonded each other.After bonding, the SOI substrate was removed from VA-CNTs and polyimide substrate, then sputtering process and surface activated bonding to polyimide substrate process were performed again to opposite side. The bonded substrates have a flexible structure and its flexibility against the electrical property was evaluated.As a result, the bonded structure was confirmed to be tolerant of bending 2 to 3 mm curvature. Furthermore, the resistivity of VA-CNT bumps was decreased from 106 to 7.8 Ω under more than 0.75 MPa compression.Thereafter, the VA-CNT bump were required to be bonded more than 0.75 MPa for good conductivity, and the conductivity was stable under the compression more than 0.75 MPa.It indicates that the flexibility of VA-CNT/polyimide substrates were effective on condition of preload to VA-CNT bumps.

The joining of graphene sheets under Ar ion beam irradiation.

In this paper, Ar ion beam irradiation was proposed as a method to join the overlapped graphene sheets and the joining process was researched by classical molecular dynamics simulation. The results showed that the ion irradiation behavior could successfully induce the joining of overlapped graphene sheets. The joining results were found to be attributed to the saturation of dangling bonds generated during irradiation. Meanwhile, it was confirmed that the ion parameters had influence on the properties of the joint and the optimum ion parameters were obtained using tensile test simulation. The optimum ion dose and ion energy were 1.9 x 10(15) ions/cm2 and 60 eV, respectively. To emphasize the importance of the irradiation, we further studied the joining possibilities of graphene sheets when the irradiation was replaced by a large force (160 nN) acting on the upper sheet and we demonstrated that the joining results wouldn't happen without the irradiation. At last, the influence of the chirality of the graphene sheets on the joining process were discussed, and it was found that graphene sheets with the same chirality had higher matching-degree, which would result in better joint.

Structure and properties of DLC–MoS2 thin films synthesized by BTIBD method

Diamond-like carbon (DLC)–MoS2 composite thin films were synthesized using a biased target ion beam deposition (BTIBD) technique in which MoS2 was produced by sputtering a MoS2 target using Ar ion beams while DLC was deposited by ion beam deposition with CH4 gas as carbon source. The structure and properties of the synthesized films were characterized by X-ray diffraction, X-ray absorption near edge structure (XANES), Raman spectroscopy, nanoindentation, ball-on-disk testing, and corrosion testing. The effect of MoS2 target bias voltage, ranging from −200 to −800V, on the structure and properties of the DLC–MoS2 films was further investigated. The results showed that the hardness decreases from 9.1GPa to 7GPa, the Young׳s modulus decreases from 100GPa to 78GPa, the coefficient of friction (COF) increases from 0.02 to 0.17, and the specific wear rate coefficient (k) increases from 5×10−7 to 5×10−6mm3N−1m−1, with increasing the biasing voltage from 200V to 800V. Also, the corrosion resistance of the DLC–MoS2 films decreased with the raise of biasing voltage. Comparing with the pure DLC and pure MoS2 films, the DLC–MoS2 films deposited at low biasing voltages showed better tribological properties including lower COF and k in ambient air environment.