Plasma Implantation Research Articles

Autologous platelet-rich plasma and fibrin-augmented minced cartilage implantation in chondral lesions of the knee leads to good clinical and radiological outcomes after more than 12 months: A retrospective cohort study of 71 patients.

The treatment of cartilage lesions remains a challenge. Matrix-associated autologous chondrocyte implantation has evolved to become the gold standard procedure. However, this two-step procedure has crucial disadvantages, and the one-step minced cartilage procedure has gained attention. This retrospective study aimed to evaluate the clinical and radiological outcome of an all-autologous minced cartilage technique in cartilage lesions at the knee joint. In this retrospective cohort study, 71 patients (38.6 years ± 12.0, 39,4% female) with a magnetic resonance imaging (MRI) confirmed grade III-IV cartilage defect at the medial femur condyle (n = 20), lateral femur condyle (n = 2), lateral tibia plateau (n = 1), retropatellar (n = 28) and at the trochlea (n = 20) were included. All patients were treated with an all-autologous minced cartilage procedure (AutoCart™). Clinical knee function was evaluated by the Tegner score, visual analogue scale, the subjective and objective evaluation form of the International Knee Documentation Committee and the Knee Injury and Osteoarthritis Outcome Score (KOOS). MRI analyses were performed by magnetic resonance observation of cartilage repair tissue (MOCART) 2.0 knee score. Follow-up examination was 13.7 ± 4.2 (12-24) months postoperative. All clinical scores significantly improved after surgical intervention (p < 0.0001), especially the subgroup sports and recreation of KOOS showed clear changes from baseline in the follow-up examination. In the postoperative MRI evaluation, 39 of 71 patients showed a complete fill of the cartilage defect without subchondral changes in 78% of the patients in the MOCART 2.0 score in the follow-up analysis. None of the patients showed adverse effects, which are linked to the minced cartilage procedure during the time of follow-up. An all-autologous minced cartilage technique for chondral lesions at the knee joint seems to be an effective and safe treatment method with good clinical and radiological short-term results. Level IV.

(Invited) Synthesis of Ion-Endohedral Fullerenes by Plasma Implantation

Endohedral metallofullerenes (EMFs), which are the hybrid materials consisting of fullerene cage and encapsulated metal(s), are one of the well-studied nanocarbon materials during the past 3 decades.[1] As a result of significant progress in the development of synthetic procedures and purification processes, a variety of different types of EMFs, such as mono-metallofullerenes, di-metallofullerenes and metal-cluster-fullerenes with various carbon-cage sizes, are currently available. We previously reported development of an efficient method to access EMFs, so-called plasma implantation.[2] This approach allowed us to achieve scalable synthesis of lithium-ion-encapsulated [60]fullerene Li+@C60 X−, a stable ionic form of lithium encapsulated fullerene. The compound can be regarded as “ion-endohedral fullerene” consisting of encapsulated ion, neutral fullerene cage and external counter anion X−, and it should not be categorized into general metallofullerenes because of its ion-pair structure. Despite the unique properties arising from its ionic natures, no other ionic metallofullerenes have been well studied so far.[3] For systematic and deeper studies on ion-endohedral fullerenes, we focused on Li+-endohedral [70]fullerene (Li+@C70) because C70 is the second abundant and therefore widely studied fullerene next to C60. The Li+@C70 was synthesized as PF6 − and TFSI− (TFSI=bis(trifluoromethanesulfonyl)imide) salts using our improved plasma implantation method followed by oxidative purification process. 7Li NMR spectrum showed a sharp singlet signal at −32.81 ppm (vs LiCl/D2O standard) indicating that the Li+ was encapsulated in the C70 cage. 13C NMR spectrum showed 5 aromatic peaks, which evidenced the defectless C70 structure. In addition to the NMR signals originated from the Li+@C70 core, 19F and 31P NMR spectra showed clear signals assigned to each external counter anion. The structure of Li+@C70 was unambiguously confirmed by X-ray crystal structure analysis of the TFSI− salt. The crystal structure showed encapsulation of Li+ by C70 cage as well as the 1:1 ion-paired structure of the cationic Li+@C70 core and external TFSI− anion.Moreover, we also performed collision experiments using sodium plasma to synthesize sodium-ion-endohedral [60]fullerene. Laser desorption ionization (LDI) mass spectrum of the crude products showed signals at m/z= 720 and 743 assignable to the molecular ion of empty C60 and the Na+@C60, respectively. The target compound was isolated as TFSI− salt by oxidative purification process followed by electrolyte-added HPLC. There was only a mass peak at m/z= 743 after the purification, which evidenced the complete removal of empty C60. 23Na NMR spectrum showed a sharp singlet signal at −59.6 ppm (vs NaCl/D2O standard), evidenced the formation of the target Na+@C60.

Heterojunction of Metal Plasmas and CoO Nanofilms for Ultraefficient Activity to Oxygen Evolution Electrocatalysts

Hydrogen production by electrolysis of water is expected to be one of the important technologies for sustainable clean energy production, but the sluggish kinetics of the oxygen evolution reaction (OER) hampers commercialization. The atomic layer deposition and high-energy metal plasma implantation were used to construct heterostructures of CoO with different thicknesses and multiple metals. Among them, the heterostructure constructed by cobalt oxide and Zr metal shows better oxygen evolution catalytic activity than other Ag, Ti, and Cr metals. With the increase of the number of Zr atoms and the thickness of the cobalt oxide layer, the OER activity first increased and then gradually decreased. The Zr500/12CoO metal–semiconductor heterojunction has a larger barrier height and more electron–hole pairs, which makes the metal surface more positively charged and promotes the adsorption of OH–. Construction of metal–semiconductor heterojunctions provides insights into the design and surface–interface modification of efficient, low-cost, and durable electrodes for water splitting applications.

Particulate cartilage and platelet-rich plasma treatment for knee chondral defects in sheep

PurposeArticular cartilage is vulnerable to multiple types of damage and it has limited reparative and regenerative capacities due to its absence of vascularity. Although a large number of therapeutic strategies exist to treat chondral defects, they have some limitations, such as fibrocartilage formation. Therefore, the goal of the present study was to evaluate the chondrogenic regenerative properties of an autologous-made matrix of particulated cartilage and platelet-rich plasma (PACI + PRP) implantation for the treatment of full-thickness chondral defects in sheep.MethodsA full-thickness 8 mm diameter cartilage defect was created in the weight-bearing area of the medial femoral condyle in both knees of 16 sheep. The right knees of all animals were treated with particulated autograft cartilage implantation and platelet-rich plasma, while the left knees were injected with Ringer’s lactate solution or hyaluronic acid. The sheep were killed 9 or 18 months after surgery. Macroscopic evaluations were performed using three different scoring systems, and histopathological evaluations were performed using a modified scoring system based on different scoring systems.ResultsThe PACI + PRP groups showed statistically significant differences in the percentage of defect repair and chondrocytes in the newly formed cartilage tissue at 18 months compared to 9 months.ConclusionsThe results suggest that macroscopic appearance, histological structure and chondrocyte repair were improved when using PACI + PRP treatment for chondral defects, producing an outcome similar to the surrounding healthy cartilage. PACI + PRP is a totally autologous, easy, and unexpensive treatment that can be performed in one-step procedure and is useful as a therapeutic option for knee chondral defects.

Comparative Clinical Trial Between Conventional Treatment and Treatment with Rich Plasma Implants in Platelets (PRP) in Patients with Pseudarthrosis in the Tibia

The objective of this work was to carry out a comparative clinical study of the cost between the Conventional Treatment and the Treatment with Platelet Rich Plasma (PRP) in patients with Pseudarthrosis in the Tibia. At human bone fractures, mainly at arising in accidents in traffic and others and your complications, represent one important condition what has jeopardized health and quality of life, in addition to crescents for the Unified Health System (SUS), so much in the treatment primary, how much of us care with their grievances. One there, the Pseudarthrosis, entity gives Orthopedics already quite known, it is one complication of fractures Where o bone no it presents features in consolidation and regeneration. This is mainly due to poor vascularization at the fracture site, inadequate or late treatment and follow-up of the fracture, or the presence of a gap between the bone fragments. Surgical treatment is the most common for Pseudoarthrosis and it may be necessary for the patient to have a vascularized bone graft in the affected region. Against in a scenery, in what if observe o increase in costs hospital at the treatment surgical of fractures, so as pension expenses at the costing in pensions and retirements, resulting in loss gives activity work and loss of Health and Quality of Life with great repercussion at economy of country, was performed a study with essay Clinical Cats Comparison of Treatment Surgical Conventional for Pseudarthrosis gives Tibia, with o use in new technologies like the injection in Plasma Rich in Platelets (PRP) at the focus gives referred lesion, in patients attended fur System single of Health (SUS). The results obtained demonstrate that treatment with Platelet Rich Plasma (PRP) is less expensive, less traumatic, effective and allows for a shorter hospital stay, in addition to improving the Quality of Life.

Analytical model of hydrogen inventory saturation in the subsurface of the wall material and comparison to Reaction-Diffusion simulations

We herein introduce an analytical model of hydrogen inventory saturation in the subsurface of materials (several micrometers depth) under plasma implantation. This model is valid for materials for which the desorption process is not limited by hydrogen recombination at the surface. It is based on a simplified assumption for the implantation of both hydrogen ions and atoms (point sources) and on a stationary approach. The model provides an approximation of the density profile of mobile/interstitial hydrogen and of the density profile of hydrogen trapped at materials defects in the subsurface layer. The analytical model shows good agreement with Reaction-Diffusion simulations of deuterium implantation in tungsten at different material temperatures. For the fusion relevant materials tungsten and beryllium, it is shown that most of the inventory is found in traps. The model gives the filling ratio of traps in the subsurface at steady-state fstat,iBULK. This simple parameter indicates how the total subsurface inventory builds up during plasma exposure and provides a simple way to understand the retention dynamics observed during non-linear Reaction-Diffusion simulations.

Few‐layered MoS2 Based Vertical van der Waals p‐n Homojunction by Highly‐efficient N2 Plasma Implantation

Abstract2D transition metal dichalcogenides have shown great potential for next‐generation microelectronic devices owing to their ability to prolong the life of Moore's law by mitigating the short‐channel effect. Recently, many efforts have been made on doping 2D films to create p‐n junctions, in which plasma implantation has been placed great expectations due to its CMOS process compatibility. However, ultrathin vertical 2D p‐n homostructure with excellent rectification behaviors have rarely been studied so far. Herein, MoS2 van der Waals p‐n homojunctions are fabricated by highly efficient N2 plasma implantation. Kelvin probe force microscope reveals the surface potential difference of ≈130 mV between n‐MoS2 and p‐MoS2. The fabricated field‐effect transistor (FET) presents a high rectification ratio up to 3.1 × 10–3 at the gate bias VGS = 20 V, which is over 20 times larger than that of the vertical homojunction obtained by surface chemical doping. The forward current is mainly dominated by both the interlayer recombination and band‐to‐band tunneling, while the ultra‐low reverse current in the order of 10 pA is governed by direct tunneling. The results demonstrate a new CMOS‐compatible way to fabricate vertical 2D homojunction, which is the basic structure of many low‐dimensional microelectronic devices.

The effect of SiN x film for H plasma implantation in p-GaN/AlGaN/GaN high electron mobility transistors

A thin SiN x film was deposited on the p-GaN layer before H plasma implantation, which cause four orders of magnitude reduction in gate reverse leakage current. The OFF-state breakdown voltage increases by 89%. It displays a more stable dynamic performance. It is believed that the decrease of gate leakage current is attributed to the increase of trap activation energies in the p-GaN layer, It is concluded that improved dynamic characteristics are owing to the fact that the SiN x film blocks the excessive H plasma into the AlGaN barrier layer and reduces the implantation damage in AlGaN barrier layer.

Study on H plasma treatment enhanced p-GaN gate AlGaN/GaN HEMT with block layer

&lt;sec&gt;High electron mobility transistors(HEMTs)show tremendous potentials for high mobility, high breakdown voltage, low conduction, low power consumption, and occupy an important piece of the microelectronics field. The high-resistivity-cap-layer high electron mobility transistor (HRCL-HEMT) is a novel device structure. Based on the hole compensation mechanism, the p-GaN is converted into high resistance semiconductor material by hydrogen plasma implantation. Thus, the surface of the p-GaN layer will have a serious bombardment damage under the hydrogen plasma implantation. In practical work, it is also very challenging in the accurate controlling of the hydrogen injection rate, injection depth and injection uniformity. To achieve the required depth of injection, the injected hydrogen plasma is often more than the required dose or multiple injections times. The energy of hydrogen plasma plays a huge influence on the surface of the p-GaN layer.The leakage current will be generated on the device surface, which deteriorates the electrical performance of the device.&lt;/sec&gt;&lt;sec&gt;In this work, to protect the surface of p-GaN layer, a 2-nm Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; film is deposited on the surface of the p-GaN cap layer to reduce the implantation damage caused by hydrogen plasma treatment. The research shows that after the device deposited Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; film prior to the hydrogen plasma treatment, the gate reverse leakage current is reduced by an order of magnitude, the ratio of &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;ON&lt;/sub&gt; to &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;OFF&lt;/sub&gt; is increased by about 3 times. Meanwhile, the OFF-state breakdown voltage is increased from 410 V to 780 V. In addition, when the bias voltage is 400 V, the values of dynamic &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;ON&lt;/sub&gt; of devices A and B are 1.49 and 1.45 respectively, the device B shows a more stable dynamic performance. To analyze the gate leakage mechanism, a temperature-dependent current&lt;i&gt; I&lt;/i&gt;&lt;sub&gt;G&lt;/sub&gt;-&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;G&lt;/sub&gt; testing is carried out, and it is found that the dominant mechanism of gate leakage current is two-dimensional variable range hopping (2D-VRH) at reverse gate voltage. The reason for reducing the gate reverse current is analyzed, and the Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; film increases the activation energy of trap level and changes the surface states of HR-GaN; furthermore, the Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; film blocks the injection of too much H plasma, thereby reducing the density of AlGaN barrier and channel trap states, and weakening the current collapse.&lt;/sec&gt;

Атомно-силовая микроскопия подповерхностных структур

Atomic force microscopy techniques of rapid indentation make it possible to obtain physical and mechanical properties simultaneously with the topography of the surface. In the general case, the obtained relief depends on the load with which the probe indents the surface. The paper presents a method of treatment of the force curves that highlights the changes in the relief at each individual step of the applied load: the surface topography (the moment of the probe touching the material), the transition region, and the sub-surface structures are separated (standard software only provides the topography corresponding to the maximum of the applied load). The proposed approach is illustrated by studying both soft and relatively stiff materials. In the first case, a two-phase polymer (polyurethane) was considered – the fibrillar structure of the polymer hidden by the soft nanolayer was shown; a study of the protein layer deposited on the surface of this polymer revealed a dendritic nanostructure of the protein film under the homogeneous surface layer. In the second case, a polymer modified by plasma implantation of carbon ions was investigated – subsurface inhomogeneities of the implanted carbon layer were shown; deformation-induced nanocracks were found to be first formed under the surface in the stiffest part of the modified layer. The paper proposes a method for estimating the thickness of the soft surface layer. It is also shown that the most complete picture of the subsurface structure does not correspond to the maximum of the applied load. The paper raises the problem of investigating adhesion interactions and the validity of using adhesion in calculating the elastic modulus in cases where the surface of an inhomogeneous material is covered by some nanolayer. The considered methods not only allow one to determine the surface relief and the features of the subsurface structures but also give the knowledge of what the researcher sees when using standard software of the device.

Stability of the threshold voltage in fluorine-implanted normally-off AlN/GaN HEMTs co-integrated with commercial normally-on GaN HEMT technology

Fluorine ion migration in normally-off AlN/GaN HEMTs fabricated by fluorine ion plasma implantation technology is evidenced. Devices under test are co-integrated into the OMMIC commercial D006GH/D01GH MMIC process, providing fluorine-free normally-on HEMTs. Gate reverse bias step-stress experiment at a drain fixed voltage of 0 V, carried out as well on normally-on ones as on normally-off ones, shows a permanent negative shift in the threshold voltage Vth of normally-off devices only. Vth degradation is starting at a VGS,stress of −8 V, with a negative shift from 0 V to −0.4 V at VGS,stress = −30 V, while the transconductance gm and gm,max remains unchanged prior to breakdown that occurred at VGS,stress ranging between −26 and −32 V. Since the positive threshold voltage of these devices is induced by F-ions dose and position, the above result suggests a possible drift of F-ions away from the 2DEG channel. A field-assisted migration mechanism of fluorine ions is proposed and supported by the absence of Vth degradation in fluorine-free normally-on devices.

Effect of plasma interface treatment on the microstructure, residual stress profile, and mechanical properties of PVD TiN coatings on Ti-6Al-4V substrates

Interface engineering is essential to enhance and to maintain the performance of protective coatings on metallic substrates. Plasma pre-treatments and coating deposition processes have shown to be an ideal solution to improve Ti-6Al-4V alloy mechanical and tribological properties, while enhancing components' durability. In the present work, we study model Titanium Nitride (TiN) coatings with three interface engineering surface treatment approaches using: a) Argon plasma, b) Titanium implantation, and c) plasma surface nitriding. In particular, we investigate the influence of the plasma pre-treatments on the microstructure, mechanical properties, especially residual stress (RS) and adhesion, of TiN coatings on Ti-6Al-4V substrates. X-Ray Diffraction, Transmission Electron Microscopy, and Transmission Kikuchi Diffraction were used as complementary techniques to evaluate the crystallographic and microstructural properties of the interfaces created by the three pre-treatment methods in order to elucidate their effect on the evolution of microstructure, hardness, RS and adhesion. The RS study involved surface and depth profiles through the coating-substrate system. Compressive RS values were found to vary between −1 GPa and −4 GPa throughout the TiN coatings, and from −0.2 to −0.8 GPa across the different interfaces. In addition, a strong RS anisotropy in dependence on the way how the substrate has been fixed to the holder (rigidly clamped or freely attached) shows a significant difference in the RS with a deviation of >100% in dependence on the orientation of coated samples during the XRD measurements. Experimental results show that Ar plasma and Ti implantation form interfaces with (200) and (111) preferential orientations within the TiN layers that exhibited a hardness of up to ~29 GPa and a Young's modulus of ~350 GPa.

Effect of hydrogen plasma implantation on the micro-structure and magnetic properties of hcp-Co80 57Fe4Ir16 thin films* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11704167, 11704317, and 11574122).

We present detailed investigations of structural and static/dynamic magnetic properties of hydrogenated hcp-Co80 57Fe4Ir16 soft magnetic thin films. Two different kinds of defects, i.e., destructive and non-destructive, were demonstrated by controlling the negative bias voltage of the hydrogenation process. Our results show that the structure and magnetic properties of our sample can be tuned by the density of the induced defects. These results provide better understanding of the hydrogenation effect and thus can be used in the future for materials processing to meet the requirements of different devices.

Autologous Tenocyte Implantation (ATI) and the Use of Collagen Scaffolds: a Case Report of a Novel Surgical Treatment for Gluteal Tendon Repair

Background: Ortho-biological therapies such as platelet-rich plasma and autologous tenocyte implantation injections are hypothesized to introduce cellular mediators such as growth factors into tendons, promoting natural healing. Methods: This case introduces a 63-year-old female with an extensive history of lateral hip pain and treatment refractory tendinopathy with tearing. She underwent open surgery to repair the gluteus medius tendon, using supplementary autologous tenocyte implantation (ATI) in conjunction with a Celgro (Orthocell, Perth, Australia) collagen scaffold. Level of evidence: 4 Results: She had normal function in the hip at 12 months. MRI scans post-operatively at 12 months showed a marked reduction in inflammation, an intact tendon and a reduction in atrophic changes in the muscle belly. Conclusion: Surgical repair of a large degenerate tear of the gluteus medius tendon, augmented with autologous tenocyte implantation in a collagen scaffold led to an excellent patient outcome and MRI findings demonstrated tendon healing with improved tendon structure and reduced inflammation.

Microstructure evolution of pure tungsten after low-energy and high-fluence He+ implantation assessed by synchrotron grazing incidence X-ray diffraction

A clear understanding on the H/He plasma implantation behavior in the plasma facing materials is a key issue to manage the implanted H/He in a future nuclear fusion reactor. In this work, the microstructure evolution of pure tungsten after low-energy (100 eV) and high-fluence (1023~1024 /m2) helium ion implantation was investigated by the synchrotron grazing incidence X-ray diffraction (S-GIXRD) and nanoindentation. Benefiting from the depth dependence of S-GIXRD and nanoindentation, it was found that the unimplanted W surface layer was composed of two zones: the compressed zone with a thickness of ~56 ± 2 nm under the top surface, which was introduced by the mechanical polishing, and the unaffected matrix. The helium implanted W surface layer was composed of four zones along the direction from the top surface to deep depth: the compressed zone with a thickness of ~46 ± 10 nm, transition zone with a thickness of ~146 ± 14 nm, expanded zone, and the matrix. The compressed zone becomes thinner after He implantation possibly owing to the formation of He-complexes. The expanded zone resulted from the helium atoms entering into the tungsten lattice, while the transition zone is a result of competition between the expanding and compressing effects.

Light Sensors Based on Silicon Nanowires

The article deals with the synthesis of silicon nanowires by the method of metal-assisted chemical etching (MACE). The purpose of this work is to use in light sensors silicon nanowires that synthesized by the MACE. To achieve this goal, it was necessary to synthesize silicon nanowires by the MACE and to study their structural features, to obtain diode structures based on silicon nanowires and to study their sensitivity to visible radiation, to establish the influence of technological parameters of the MSHT process on the sensitivity of photo sensors and sensors. Today, nanostructures are obtained by the method of reactive ion etching, electrochemical etching and plasma implantation. However, most of these methods require sophisticated process equipment. Metal-assisted chemical etching (MACE) method is very promising for nanostructures creation. Two-stage MACE was used to make the samples. In the first stage, silver nanoparticles were deposited on the surface of single crystalline silicon. In the second stage, the samples were etched in a solution of water, hydrogen peroxide and hydrofluoric acid and, as a consequence, a structured surface was obtained. It should be noted that the samples were treated at different times of each of the stages of MACE. Based on the obtained samples, diode light sensors with different photoelectric parameters were synthesized. For the sensors obtained, the sensitivity was calculated in the photodiode and photogenerator modes, and the volt-ampere, luxury-ampere characteristics and dependences of the current density on the illumination density were constructed. structured silicon has a mesh-like appearance, where the dark regions are gaps (pores) and the light ones are silicon (pore walls, nanowires). First, compare the samples with different deposition times. It is seen that as the deposition time of the particles increases from 10 to 40 s, a more developed silicon surface is formed. Also, with the duration of deposition 40s on the silicon surface there are needle-like formations, which according to the results in the work are silver dendrites. All the above characteristics were analyzed for the effect of the deposition time of silver particles t1 and etching time t2 on them. Studies have shown that the optimum technological conditions of metal assisted chemical etching of silicon for using in light sensors are the following conditions: the deposition time of silver particles 40c, etching time 30 min, the content of hydrogen peroxide in the second solution of 0.8 ml. This mode of synthesis of the structuring of silicon substrates provides maximum photosensitivity ratios both in the photodiode (1.53 mA / lmV) and in the photogenerator (304 mA / W) modes. The influence of the concentration of H2O2 used in the second stage is crucial only for the photocurrent, which is not critical, and the influence of the AgNO3 concentration in the first stage of MACE does not have a significant effect on the parameters.

Modification of polyether ether ketone by low-temperature plasma and ion implantation method for use in medicine and biology

The review concerns modification of polyether ether ketone (PEEK) using low-temperature plasma and ion implantation and presents the results of studies on the surface properties of modified PEEK samples obtained by wetting angle measurements, X-ray photoelectron spectroscopy, Fourier-IR-spectroscopy, scanning electron microscopy, and atomic force microscopy. This made it possible to investigate changes in the hydrophilicity, chemical structure, and morphology of the modified PEEK surface. The thermal and mechanical properties of the plasma-treated polymer are analyzed. Examples of biomedical applications of the modified PEEK are given.

Prediction of temperature range for the onset of fuzz formation in helium-plasma-implanted tungsten

We describe model predictions of the temperature dependence for the formation of fuzz, a nanofiber-like surface feature, on helium-plasma-irradiated tungsten surfaces under conditions similar to those at the divertor of fusion reactors. Temperature influences the onset of fuzz formation through the strongly temperature-dependent pressure of subsurface helium bubbles formed by plasma implantation and surface diffusivity of tungsten, in addition to the thermal softening of the elastic moduli of tungsten. We explore the effects of helium concentration in the plasma-implanted tungsten and helium bubble size, report surface response diagrams predicted over a broad temperature range, and interpret the trends exhibited in such diagrams.

Effects of carbon and nitrogen plasma immersion ion implantation on bioactivity of zirconia.

Zirconia is considered the most promising alternative material to titanium implants. However, zirconia is a biologically inert material and its surface modification is essential to obtain efficient osseointegration. Plasma immersion ion implantation (PIII) is a controllable and flexible approach that constructs functional groups on the surface of biomaterials and enhances osteogenic ability of host osteoclast cells. Zirconia disks were randomly divided into 4 groups (n = 50/group): (1) Blank, (2) C60N0, (3) C60N6, and (4) C60N18. Carbon and nitrogen plasma immersion ion implantation on zirconia (C and N2-PIII) surface modification was completed with the corresponding parameters. When zirconia was modified by carbon and nitrogen plasma implantation, a new chemical structure was formed on the material surface while the surface roughness of the material remained unaltered. The nitrogen-containing functional groups with high potential were introduced but the bulk crystal structure of zirconia was not changed, indicating that the stability of zirconia was not affected. In vitro data showed that zirconia with high surface potential promoted adhesion, proliferation, and osteogenic differentiation of BMSCs. C60N6 was found to be superior to the other groups. Our results demonstrate that a zirconia surface modified by C and N2-PIII can introduce desirable nitrogen functional groups and create a suitable extracellular environment to promote BMSCs biological activity. Taken together, these results suggest that C and N2-PIII modified zirconia is a promising material for use in the field of medical implantation.

Two-step cycling process alternating implantation and remote plasma etching for topographically selective etching: Application to Si3N4 spacer etching

This article proposes an original method to achieve topographically selective etching. It relies on cycling a two-step process comprising a plasma implantation step and a removal etching step using remote plasma source process. Both steps can be achieved in the same reactor prototype chamber, which has the capability to produce both capacitively coupled plasma and remote plasma (RP) discharges. It is shown that in RP processes, an incubation time exists before the etching starts. The introduction of a plasma implantation step prior to the RP step allows us to selectively functionalize the horizontal surfaces of the material with respect to the vertical surfaces, thanks to the ion directionality. The modifications induced by the implantation allow us to modify the incubation time between an implanted and a nonimplanted material offering a process window with infinite etch selectivity between horizontal and vertical surfaces. This approach has been demonstrated on Si3N4 blanket films with the perspective to be applied to the Si3N4 spacer etching process in which etch selectivity is a key issue. For this particular application, a cycling process comprising an H2 plasma implantation and a He/NH3/NF3 remote plasma process has been developed. The H2 implantation modifies the Si3N4 surface state by incorporating oxygen contaminants coming from the reactor wall and creating dangling bonds. This surface functionalization considerably reduces the incubation time. New insights into the etching mechanisms of Si3N4 films exposed to NH3/NF3 remote plasma are proposed and explain why the presence of Si–O bonds is mandatory for the initiation of the etching.