Plasma Ion Implantation Research Articles

Prospects for band gap engineering by plasma ion implantation

AbstractThe suitability of plasma ion implantation (PII) for band gap engineering will be examined by calculations of the band gap's spatial variation. Plasma Ion Implantation is a method to modify the surface and subsurface properties of materials; the ions surrounding the target are forced into all plasma exposed surfaces simultaneously by virtue of high‐voltage pulses. We calculated the fluence and the ion energy distribution from the dynamic sheath model. The distribution of the ions within the target is subsequently simulated by the TRIDYN software. The concentration profiles are converted into a spatial variation of the band gap. The challenges inherent to the method are discussed by means of the examples of carbon (C) PII in silicon (Si) as well as nitrogen (N) PII in gallium arsenide (GaAs). The ion distribution within the material of the former example is suitable for the formation of the Si‐C alloy. On the other hand, the distribution of N ions in GaAs prevents the formation of the Ga‐As‐N alloy. The discussed methods could be a powerful tool for the prediction of materials properties from the plasma processing parameters, thus helping to design materials. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electroluminescence in plasma ion implanted silicon

AbstractElectroluminescent silicon is very desirable for its potential applications in computing and telecommunications. Plasma Ion Implantation (PII) is a means to modify the surface and sub‐surface properties of silicon to produce luminescent centres. Silicon to be treated with PII is immersed in low‐temperature plasma and biased to a high, negative voltage; this accelerates ions into the sample and implants them beneath its surface. The material is subsequently annealed in a furnace and fitted with thin gold and aluminium contacts. Samples of crystalline silicon were implanted with H ions, C ions, and N ions and found to emit visible light when subjected to electric current. Nearly every sample emitted light at ∼460 nm and ∼630 nm; these luminescence bands are commonly observed in X‐ray excited optical luminescence studies of silicon nanostructures and have been attributed to silicon dioxide (SiO2) and the silicon‐SiO2 interface, respectively [1]. Other luminescent bands may be the product of nanostructures and defects created by the implantation process and subsequent annealing. This presentation will explore in detail the results of these experiments and the potential of PII for modifying the luminescent properties of elemental silicon. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Silicon electroluminescent device production via plasma ion implantation

AbstractWe discuss the technique of plasma ion implantation (PII) and the type of luminescent centers which can be produced by it. We have focused on high‐dose ion implantation into silicon for bandstructure modification. We have produced electroluminescent silicon using a range of plasma ion species including H+, C+, N+ and a range of ion implant conditions. Analyses of the spectra of electroluminescent centers produced by this technique have been performed. Further work will be required to determine the exact physical mechanisms responsible for these effects. Future prospects for electroluminescent devices based on these effects will be discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

An All Solid-State Pulsed Power Generator for Plasma Immersion Ion Implantation (PIII)

An all solid-state pulsed power generator for plasma immersion ion implantation (PIII) is described. The pulsed power system is based on a Marx circuit configuration and semiconductor switches, which have many advantages in adjustable repetition frequency, pulse width modulation and long serving life compared with the conventional circuit category, tube-based technologies such as gridded vacuum tubes, thyratrons, pulse forming networks and transformers. The operation of PIII with pulse repetition frequencies up to 500 Hz has been achieved at a pulse voltage amplitude from 2 kV to 60 kV, with an adjustable pulse duration from 1 μs to 100 μs. The proposed system and its performance, as used to drive a plasma ion implantation chamber, are described in detail on the basis of the experimental results.

Coating deposition using vacuum arc and ablation metal plasma

An innovative concept in the development of advanced coating deposition and ion implantation method including an application of filtered DC metal plasma or ablation plasma and high-frequency short-pulsed negative bias voltage with a duty factor in the range 10–99% is considered. The regularities of metal ion implantation and vacuum arc metal plasma or ablation plasma deposition for conducting and insulating materials are considered. It was shown that plasma based ion implantation as well as high-concentration plasma ion implantation with compensation of ion surface sputtering by plasma deposition as well as ion-assisted coating deposition may be realized for metal and dielectric samples by variation of negative bias potential in the range of 0–4·10 3 V, pulse repetition rate smoothly adjusted in the range of (2–4.4) × 10 5 pps and pulse duration in the range of 0.5–2 µs. It was experimentally shown that at coating deposition from ablation plasma obtained by high intensity ion beam ( j = 300 A/cm 2, E = 350 keV, τ = 90 ns) influence on the target, the breakdown of the plasma sheet occurred at dc negative bias potential on a substrate more than 60 V. The transfer to 0.5 µs duration pulses allowed us to increase the bias potential up to − 4 kV. The possibility of high-frequency, short-pulsed plasma-immersion ion implantation and deposition method application for coating deposition from vacuum arc and ablation plasma with high adhesive strength and improved exploitation characteristics is discussed in the paper.

Characterization of Titanium Nitride Coatings Deposited by Metal Plasma Ion Pre-Implantation and Cathodic Arc Evaporation

Titanium nitride coatings are deposited using a hybrid system of cathodic arc evaporation and metal plasma ion implantation. The implant sources selected are Ti and C. Subsequent ion bombardment along with the conventional cathodic arc evaporation are applied to the deposition of TiN film. Implantation causes the increase of nucleation site density, favoring the formation of denser films. The increased density of nucleation sites due to high-energy ion impingement and the surface modification contribute to the fine microstructure of the TiN films. The critical loads evaluated from scratch tests are 60 N, 70 N and 78 N for unimplant-TiN, C+/TiN and Ti2+/TiN, respectively. It demonstrates the advantage of implant pre-treatment on adhesion strength. Pre-implantation of high dose Ti2+ and C+ (about 2 x 10(17) ions/cm2) also results in an improvement of the mechanical properties. Pin-on-disk wear analyses demonstrate a prolonged wear life of TiN coatings by Preimplantation of Ti2+ and C+ ions. The TiN surface modification by pre-implant ions (Ti2+ or C+) is investigated through the microstructure, adhesion strength and wears resistance.

Measurement of hydrogenic retention and release in molybdenum with the DIONISOS experiment

Molybdenum targets are exposed in the DIONISOS experiment to a deuterium (D) plasma ( Γ D ∼ 10 21 m −2 s −1) at target biases of 30–350 V and target temperatures of 300–700 K while simultaneously diagnosing the D in the surface with a 3.5 MeV 3He ion beam. The 3He diagnostic beam creates displacements in the Mo lattice which can then trap D, allowing retention far beyond the plasma ion implantation range. The conversion of displacements to trap sites averaged over the ion range is non-linear with a scaling (dpa) α, 0.25 ⩽ α ⩽ 0.5. The beam-induced traps are distributed from the surface to the end of range as opposed to the damage (dpa) profile that is concentrated at the end of range. Measurement of the near-surface D time-dependence has allowed inference of an effective surface recombination rate, which is lower than predicted by theory and at the low end of those found in literature.

Ion implantation of oxygen and nitrogen in CpTi

A study of the plasma ion implantation (PIII) of commercially pure titanium (CpTi) at a low voltage (<4 kV) is presented. The processed samples were treated in divers mixtures of O and N in order to achieve biocompatible oxidized and nitrided layers as well as to enhance their superficial hardness. In this way, the low wearing resistance of CpTi can be avoided while creating a biocompatible rutile phase titanium oxide layer for a better bone integration. A form of synergy associated to the dependence of microhardness on the implanted layer disposition is identified. Thus, an upper rutile layer is immediately followed by another one, in which titanium, a nitride (TiN 0.26) and rutile coexist. The latter leads to a superior microhardness performance. Most of all these surface treatments of titanium, when applying an 80%N–20%O mixture, yield higher corrosion resistance parameters with respect to the main metallic materials used in prosthetics, including the Co–Cr–Mo alloys, albeit excluding CpTi.

MODIFICATION OF WETTING PROPERTIES OF PMMA BY IMMERSION PLASMA ION IMPLANTATION

Advancing and receding contact angles below 5° have been obtained on PMMA surfaces with the implantation of argon and oxygen ions. The ion implantations were performed by means of the Immersion Plasma Ion Implantation (IPII) technique, a hybrid between ion beams and immersion plasmas. Characterization of treated PMMA surfaces by means of XPS and its combination with chemical derivatization (CD-XPS) have revealed the depletion of oxygen and the creation of dangling bonds, together with the formation of new chemical functions such as –OOH , –COOH and C = C . These observations provide a good explanation for the strong increase of the wetting properties of the PMMA surfaces.

High-performance nanoadhesive bonding of titanium for aerospace and space applications

In this investigation, attempts are made to prepare high-performance nanoadhesive bonding of titanium for its essential applications to aviation and space. The high-performance nanoadhesive is prepared by dispersing silicate nanoparticles into the ultra-high-temperature-resistant epoxy adhesive at 10 wt% ratio with the matrix adhesive followed by modification of the nanoadhesive after curing under high-energy radiation for 6 h in the pool of SLOWPOKE-2 nuclear reactor with a dose rate of 37 kGy/h to promote crosslink into the adhesive. Prior to bonding, the surfaces of the titanium sheets are mechanically polished by wire brushing, ultrasonically cleaned by acetone and thereafter the titanium sheets are modified by plasma ion implantation using plasma nitriding. The titanium surface is characterized by X-ray photoelectron spectroscopy (XPS). The thermal characteristics of the epoxy adhesive and the high-performance nanoadhesive are carried out by thermal gravimetric analysis (TGA). The TGA studies clearly shows that for the basic adhesive there is a weight loss of the adhesive, however, in the case of epoxy–silicate nanoadhesive, there is almost 100% retention of weight of the adhesive, when the adhesive is heated up to 350 °C. Lap shear tensile strength of the joint increases considerably, when the titanium surface is modified by plasma-nitriding implantation. There is a further massive increase in joint strength, when the plasma-nitriding implanted titanium joint is prepared by nanosilicate–epoxy adhesive and further modification of the adhesive joint under high-energy radiation results a further significant increase in joint strength. In order to simulate with aviation and space climatic conditions, the joints are separately exposed to cryogenic (−196 °C) and elevated temperature (+300 °C) for 100 h and thermal fatigue tests of the joints are carried out under 10 cycles by exposing the joint for 2 h under the above temperatures. When the joint completely kept at ambient condition and the joint strength compared with those joints exposed to aviation and space climatic conditions, it is observed that the joint could retain 95% of the joint strength. Finally, to understand the behavior of the high-performance silicate–epoxy nanoadhesive bonding of titanium, the fractured surfaces of the joints are examined by scanning electron microscope.

Plasma ion implantation to thin polymer foils

AbstractPlasma ion implantation and deposition of polymeric materials has gained substantial interest in recent years. This paper will present numerical results on initial potential on top surface and some examples on ion implantation of thin polymer foils. The results demonstrate that the thickness and permittivity of treated samples have a critical influence on initial potential drop across the insulating objects. The smaller thickness and larger permittivity are beneficial for ion implantation. Duplex films of Al2O3/SiO2 have been fabricated using arc plasma ion implantation and deposition. The films may substantially increase atomic‐oxygen resistance of Kapton foils, which have been frequently utilized in satellites in low‐earth‐orbit (LEO) environment. The mass loss of treated samples may decrease by one quarter of magnitude compared to that of control sample. The PET foils have also been implanted using C2H2 plasma ion implantation. The experimental results show that ion implantation may effectively enhance the gas barrier capability. (© 2008 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Comparison of chemical binding states between ultra shallow plasma doping (PD) and ion implantation (I/I) samples by using hard X‐ray photoelectron spectroscopy (HX‐PES)

AbstractWe measured HX‐PES (Si 1s) of ultra low energy ion implantion (I/I) samples combined with Ge pre‐amorphizaiton ion implantation (Ge‐PAI) before and after spike RTA, and compared it with that of plasma doping (PD) samples. As‐doped I/I sample showed higher hole density compared to as‐doped PD sample due to lower defect induced carrier trap. Ge‐PAI+I/I sample showed strong asymmetric in lower binding energy region due to Si‐Ge bonding. After spike RTA, PD sample showed superior impurity activation than that of Ge‐PAI+I/I sample. Both Ge‐PAI+I/I and PD sample showed excellent recrystallization after spike RTA. (© 2008 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Fluorine plasma ion implantation in AlGaN∕GaN heterostructures: A molecular dynamics simulation study

Fluoride-based plasma treatment is a robust technique that enables shallow implantation of fluorine ions into group III-nitride epitaxial structures. This technique has been used to achieve robust threshold voltage control of the AlGaN∕GaN high electron mobility transistors and led to the realization of self-aligned enhancement-mode devices. To reveal the atomic scale interactions and provide a modeling tool for process design and optimization, a molecular dynamics (MD) simulation is conducted for fluorine plasma ion implantation. Specific potential functions are applied to calculate the interactions among atoms and simulate the dynamic process of fluorine ions’ penetration and stopping in III-nitride materials. The MD simulation provides accurate information on dopant profiles that are verified by secondary-ion-mass-spectrum measurements. Defect formation and distributions, that are critical in process development, are also investigated.

Effects of MPII-implanted titanium on the electrochromic properties of tungsten trioxide

There are great interests in electrochromic (EC) technology for smart windows and displays over the last decade. The substrate, a conductive glass being coated indium tin oxide (ITO) thin films, deposited tungsten trioxide (WO 3) using radio-frequency (RF) sputtering and implanted Ti by a metal–plasma ion implantation (MPII) in this study. The optical density (when the implanted dose is less than 2 × 10 15 ions/cm 2) is approximately 1.6 times the unimplanted Ti. At low implanted dose +6 valence tungsten ions improve optical density. At high implanted dose, low-valence tungsten ions reduce the optical density.

Comparison of composition of ultra-thin silicon oxynitride layers’ fabricated by PECVD and ultrashallow rf plasma ion implantation

In this paper differences in chemical composition of ultra-thin silicon oxynitride layers fabricated in planar rf plasma reactor are studied. The ultra-thin dielectric layers were obtained in the same reactor by two different methods: ultrashallow nitrogen implantation followed by plasma oxidation and plasma enhanced chemical vapour deposition (PECVD). Chemical composition of silicon oxynitride layers was investigated by means of X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The spectroscopic ellipsometry was used to determine both the thickness and refractive index of the obtained layers. The XPS measurements show considerable differences between the composition of the fabricated layers using each of the above mentioned methods. The SIMS analysis confirms XPS results and indicates differences in nitrogen distribution.

Effects of ion implantation on the microstructure and residual stress of filter arc CrN films

Chromium nitride coatings were deposited using a hybrid physical vapor deposition (PVD) system containing a filter arc deposition (FAD) and a metal plasma ion implantation source (MPII). Exactly how surface residual stress affects film characteristics is investigated using glancing incident X-ray diffraction (GIXRD) and pole figure analyses. Compared with unimplanted CrN, implanted carbon typically increases compressive residual stress and hardness. Wear resistance was also improved by implanted carbon.

Active Charge/Discharge IGBT Modulator for Marx Generator and Plasma Applications

In this paper, we present a Marx-stackable insulated-gate-bipolar-transistors-based modulator for plasma ion implantation and other pulsed high voltage-high peak power applications. Active control of charging and discharging cycles permits rigid pulse forms, arbitrary duty cycles and internal efficiencies exceeding 90%. We demonstrate a 20-kV 15-A generator using a 2-kV Marx generator to drive a pulse transformer

Plasma-Treated Biomaterials

Atmospheric pressure plasma spraying is currently used to fabricate relatively thick ceramic coatings for orthopedic applications such as hip joints replacements. We have recently fabricated bioactive nanostructured titanium oxide coatings that are bioactive and conducive to the growth of apatite. The materials are synthesized by nanoparticle atmospheric pressure plasma spraying followed by low-pressure plasma immersion ion implantation (PIII). Surface bioactivity can also be induced by irradiating the nanostructure TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> coatings with ultraviolet light instead of hydrogen plasma ion implantation. PIII is a useful method to treat other types of biomaterials to enhance the surface bioactivity. Recent applications of the technology to modify orthopedic materials as well as biocompatible and antibacterial coatings are described in this invited paper

High frequency short-pulsed plasma-immersion ion implantation or deposition (HFSPPI 3D)

An innovative concept in the development of advanced coating deposition and ion implantation method including an application of filtered dc metal plasma and high-frequency short-pulsed negative bias voltage with a duty factor in the range of 10–99% is considered. The systematics of metal ion implantation and metal plasma deposition for conducting and insulating materials were investigated. Experimentally, it has been shown that metal plasma based ion implantation as well as high-concentration metal plasma ion implantation with compensation of ion surface sputtering by metal plasma deposition, as well as ion-assisted coating deposition, can be realized by a variation of bias potential ranging from 0–4 · 10 3 V, pulse repetition rate smoothly adjusted in the range 2–4.4 · 10 5 pps and pulse duration ranging from 0.5 to 2 μs. Special features of the material treatment method depending on sample conductivity and thickness, plasma concentration, pulse repetition rate and amplitude and duty factor have been examined. The measurements of the resulting adhesion strength, microhardness investigations of the Ti coatings on the stainless steel and glass-ceramic substrates are presented.

1011 メタンガスを用いたプラズマイオン注入によるDLC膜の深さ方向分析(表面改質による機械の高性能化)

1011 メタンガスを用いたプラズマイオン注入によるDLC膜の深さ方向分析(表面改質による機械の高性能化)