Ion Implantation Process Research Articles

Nanograins on Ti-25Nb-3Mo-2Sn-3Zr alloy facilitate fabricating biological surface through dual-ion implantation to concurrently modulate the osteogenic functions of mesenchymal stem cells and kill bacteria

Surface mechanical attrition treatment (SMAT) method is an effective way to generate nanograined (NG) surface on Ti-25Nb-3Mo-2Sn-3Zr (wt.%) (named as TLM), a kind of β-type titanium alloy, and the achieved nanocrystalline surface was proved to promote positive functions of osteoblastic cells. In this work, to further endow the NG TLM alloy with both good osteogenic and antibacterial properties, magnesium (Mg), silver (Ag) ion or both were introduced onto the NG TLM surface by ion implantation process, as a comparison, the Mg and Ag ions were also co-implanted onto coarsegrained (CG) TLM surface. The obtained results show that subsequent ion implantation does not remarkably induce the surface roughness and topography alteration of the SMAT-treated layers, and it also has little impact on the microstructure of the SMAT-derived β-Ti nanograins. In addition, the implanted Mg and Ag ions are observed to exist as MgO and metallic Ag nanoparticles (NPs) embedding tightly in the β-Ti matrix with grain size of about 15 and 7 nm, respectively. Initial cell adhesion and functions (including proliferation, osteo-differentiation and extracellular matrix mineralization) of rabbit bone marrow mesenchymal stem cells (rBMMSCs) and the bacterial colonization of Staphylococcus aureus (S. aureus) on the different surfaces were investigated. The in-vitro experimental results reveal that the Mg and Ag single-ion implanted NG surface either significantly promotes the rBMMSCs response or inhibits the growth of S. aureus, whereas the Mg/Ag co-implanted NG surface could concurrently enhance the rBMMSCs functions as well as inhibit the bacterial growth compared to the NG surface, and this efficacy is more pronounced as compared to the Mg/Ag co-implantation in the CG surface. The SMAT-achieved nanograins in the TLM surface layer are identified to not only play a leading role in determining the fate of rBMMSCs but also facilitate fabricating dual-functional surface with both good osteogenic and antibacterial activities through co-implantation of Mg and Ag ions. Our investigation provides a new strategy to develop high-performance Ti-based implants for clinical application.

Distributions of silicon implanted in GaN epitaxial layers

Ion-doped layers of n+ - GaN were formed with a high degree of activation of the embedded impurity. Si+ ion implantation was performed in GaN epitaxial layers grown by MOCVD. Profiles of embedded silicon in gallium nitride were calculated. The experimental profile obtained by secondary ion mass spectrometry is compared with the calculated one. Optimal implantation modes were determined, the implantation dose is 1015 cm−2, and the energy is 50 keV. Activation of the embedded impurity was performed by high-temperature photon annealing in a nitrogen medium using SiO2 and Si3N4 protective coatings. The influence of the annealing temperature on the morphology of protective coatings is considered. The SRIM program was used to simulate the process of ion implantation of silicon at the interface of the AlGaN/GaN heterostructure through SiO2 dielectric films of different thickness. Ohmic contacts were formed on the ion-doped basis of the Ti/Al/Ni/Au metallization system. The calculation of the contact resistance of ohmic contacts showed that the use of ion doping through a 50 nm thick silicon dioxide film reduces the contact resistance from 1.2 Ω·mm to 0.8 Ω·mm. The use of ion implantation technology in the manufacture of diode structures reduces the direct voltage drop and the minimum voltage drop is achieved when using implantation through a 50 nm SiO2 mask, this is due to the location of the maximum distribution of the implanted impurity at a depth corresponding to the occurrence of a two-dimensional electron gas.

Modelling of nitrogen multi-energy ion implantation into WC-Co indexable knives for wood-based materials machining

Modelling of nitrogen multi-energy ion implantation into WC-Co indexable knives for wood-based materials machining. The paper presents the results of the modelling of multi-energy ion implantation processes of nitrogen to WC-Co indexable knives for wood-based materials machining. The modelling was performed for implantation of N++N2+ ions, for implanters without and with mass separation. Additionally, modelling for average charge state and for the extended implantation case was executed. The best results, i.e. flat and long plateau region and the most favourable plateau/multi ratio were obtained for N+ ions.

Realization of Precise Tuning the Superconducting Properties of Mn-Doped Al Films for Transition Edge Sensors

Magnetic impurities in metallic superconductors are important for both fundamental and applied sciences. In this study, we focused on dilute Mn-doped aluminum (AlMn) films, which are common superconducting materials used to make transition edge sensors and other superconducting devices. We developed a multi-energy ion-implantation technique to make AlMn films. Compared with frequently used sputtering techniques, ion-implantation provides more precise control of the Mn doping concentration in the AlMn films. It enables us to fabricate reliably AlMn films with a different superconducting transition temperature (T-c) that can match a variety of application needs. We also found that the superconducting transition temperature drops with increasing film thickness for samples with the same nominal concentration of Mn dopants. The dependence of T-c on the film thickness is attributed to the increasing implantation energy. By quantitatively analyzing the curves of T-c versus the Mn doping concentration, we propose that Mn dopants act as magnetic impurities and suppression of superconductivity is counteracted by the antiferromagnetic Ruderman-Kittel-Kasuya-Yosida interaction among Mn dopants, which is influenced by the defects induced in the ion-implantation process.

Exploration of Solid Phase Epitaxy of 3C-SiC on Silicon

In this contribution we investigate the formation at high temperature of an oriented 3C-SiC seed on various orientations of Si substrates “pre-carbonized” through Plasma Immersion Ion Implantation (PIII) process.

Ion Implanted Phosphorous for 4H-SiC VDMOSFETs Source Regions: Effect of the Post Implantation Annealing Time

Van der Pauw devices have been fabricated by double ion implantation processes, namely P+ and Al+ co-implantation. Similarly to the source area in a SiC VD-MOSFET, a 5 × 1018 cm-3 P plateau is formed on the top of a buried 3 × 1018 cm-3 Al distribution for electrical isolation from the n- epilayer. The post implantation annealing temperature was 1600 °C. Annealing times equal to 30 min and 300 min have been compared. The increase of the annealing time produces both an increase of electron density as well as electron mobility. For comparison a HPSI 4H-SiC wafer, 1×1020 cm-3 P+ ion implanted and 1700 °C annealed for 30 min was also characterized.

Orientation and morphology of Pt nanoparticles in γ-alumina processed via ion implantation and thermal annealing

Structure and chemistry of metal/metal-oxide interfaces are critical for many catalytic processes and sensing. Pristine interfaces of Pt and γ-Al2O3 were fabricated using high-energy ion implantation and thermal processing. Amorphous regions of alumina develop in single crystal α-alumina during Pt+ implantation and an 800 °C thermal treatment crystalizes amorphized alumina to γ-Al2O3 and allows Pt ions to precipitate within the developing γ-alumina, yielding Pt nanoparticle tetrahedra terminated by {111} surfaces. The phase of alumina that developed and the distribution, morphology, and orientation of Pt nanoparticles was determined using x-ray diffraction, Rutherford backscattering spectrometry, transmission electron microscopy and scanning transmission electron microscopy.

4H-SiC surface morphology after Al ion implantation and annealing with C-cap.

The root mean square (rms) surface roughness extracted from atomic force microscopy is widely employed to complement the characterisation of ion implantation processes in 4H-SiC. It is known that the protection of a carbon film eliminates or mitigates roughening of the SiC surface during postimplantation annealing. This study, based on a rich original data collection of Al+ ion implanted 4H-SiC samples, allows for a quantitative description of the surface morphology as a function of the annealing temperature and time and of the Al implanted concentration. With increasing thermal budget, the evolution from flat, to blurred with ripples, granular, and finally jagged surface, results in a monotonous increase in the root mean square roughness. Additional information is given by the trends of the roughness exponent and of the correlation length, extracted from the height-height correlation function, which account for the surface evolution below 1700°C and for the effect of the Al implanted concentration on the ripple size, respectively. A combination of low roughness parameter and high correlation length identify the transition from ripples to jagged morphology. LAY DESCRIPTION: Selective area doping is a key step in the fabrication of hexagonal Silicon Carbide (4H-SiC) power electronic devices. It is achieved by ion implantation followed by a high temperature postimplantation annealing to restore the lattice and electrically activate the dopants. Aluminium, the preferred p-type dopant, is electrically activated at temperature ranging between 1500°C and 2000°C. The time required to complete the activation process is longer the lower the annealing temperature, spanning between some minutes and hundreds of hours. During annealing, 4H-SiC wafers are encapsulated by a temperature-resistant carbon layer (C-cap) in order to avoid step bunching and reduce surface roughening. Nevertheless, surface modifications can occur at high temperature. For this reason, the characterisations of 4H-SiC doping processes report not only the electrical activation of the dopants, but also the root mean square surface roughness obtained at the end of the process. However, rms values can be scattered because technological parameters such as the heating system and the way to deposit and remove the C-cap can affect the final result as well as the process parameters. Furthermore, the C-cap resistance to long annealing has been proven only by electrical measurements, but the surface morphology has never been observed. This work presents a quantitative characterisation of the surface morphology of Al implanted 4H-SiC as a function of the annealing temperature, time and of the Al implanted concentration, independent of the heating system and of the C-cap technology. The produced sample collection allowed to correlate characteristic surface features with the corresponding quantities extracted from image analysis that can be more sensitive to process parameters than the sole rms. These findings can be used to enrich process optimisation tools.

Development of photodiode via the rapid melt growth (RMG) materials for energy conversion device

<span>Germanium (Ge) photodiodes were fabricated with the new RMG crucible materials that were established in this study. Results show that Ge large square patterns with size of 208 µm x 208 µm were unable to be achieved if ion implantation process was used in formation of photodiode. Delamination can be observed on all test samples during polycrystalline silicon (poly-Si) deposition at 620 <sup>o</sup>C. This result was in contrast to a previous intrinsic Ge test structure, where good formation of squares with size similar to that 208 µm x 208 µm had been successfully attained even with high annealing temperature above 938 <sup>o</sup>C. This indicates that doping through ion implantation has affected Ge film and caused delamination even at low temperature. However, good formations of Ge stripes were attained along with the ion implantation process in fabricating the photodiode. Results show that the sheet resistance of Ge stripe has significantly decreased compared to previous Ge resistors. The better resistance is due to the thicker (500 nm) Ge layer. In the case of Ge stripes with a p-i-n junction, only small fraction of test samples have shown a diode characteristic but with high leakage current. Results of I-V measurement show that a large fraction of test samples produced resistor characteristics. The high leakage current is believed due to the fact that the Ge films formed at this stage were polycrystalline in structure. Thus the grain size of Ge stripe has affected the performance. Slight changes on the I-V characteristic of single Ge can be observed when samples were tested under illumination. Therefore, it has potential to be used for future development of energy conversion device. </span>

Strain Modification of PECVD Nitride By Plasma Immersion Ion Implantation Processes

The impact of Plasma Immersion Ion Implantation (PIII) processes with various species (hydrogen, helium and nitrogen) on the stress of a tensile PECVD nitride film was evaluated. Ellipsometry measurements indicated no consumption of the nitride but a change in the optical index, signaling a material modification. The initial stress of the nitride was modified by PIII from tensile to mechanically neutral and even compressive. Hydrogen and nitrogen appeared to be more efficient to modify the stress than helium.

Engineered telecom emission and controlled positioning of Er3+ enabled by SiC nanophotonic structures

Abstract High-precision placement of rare-earth ions in scalable silicon-based nanostructured materials exhibiting high photoluminescence (PL) emission, photostable and polarized emission, and near-radiative-limited excited state lifetimes can serve as critical building blocks toward the practical implementation of devices in the emerging fields of nanophotonics and quantum photonics. Introduced herein are optical nanostructures composed of arrays of ultrathin silicon carbide (SiC) nanowires (NWs) that constitute scalable one-dimensional NW-based photonic crystal (NW-PC) structures. The latter are based on a novel, fab-friendly, nanofabrication process. The NW arrays are grown in a self-aligned manner through chemical vapor deposition. They exhibit a reduction in defect density as determined by low-temperature time-resolved PL measurements. Additionally, the NW-PC structures enable the positioning of erbium (Er3+) ions with an accuracy of 10 nm, an improvement on the current state-of-the-art ion implantation processes, and allow strong coupling of Er3+ ions in NW-PC. The NW-PC structure is pivotal in engineering the Er3+-induced 1540-nm emission, which is the telecommunication wavelength used in optical fibers. An approximately 60-fold increase in the room-temperature Er3+ PL emission is observed in NW-PC compared to its thin-film analog in the linear pumping regime. Furthermore, 22 times increase in the Er3+ PL intensity per number of exited Er ions in NW-PC was observed at saturation while using 20 times lower pumping power. The NW-PC structures demonstrate broadband and efficient excitation characteristics for Er3+, with an absorption cross-section (~2 × 10−18 cm2) two-order larger than typical benchmark values for direct absorption in rare-earth-doped quantum materials. Experimental and simulation results show that the Er3+ PL is photostable at high pumping power and polarized in NW-PC and is modulated with NW-PC lattice periodicity. The observed characteristics from these technologically friendly nanophotonic structures provide a promising route to the development of scalable nanophotonics and formation of single-photon emitters in the telecom optical wavelength band.

Effect of ion implantation on the properties of implantable aluminum alloys

The effect of ion-implantation processing of N2 + ions in aluminum alloys 1160, 1190 and 1420 on their microhardness, stresses of II type and microstructure is discussed in this article. During research, prototypes of aluminum alloys were hardened by ion implantation in the accelerator. The implantation mode, selected from literature, was used to test the possibility of hardening aluminum alloys by implantation with N2 + ions. The ion beam was scanned in a horizontal plane at a beam height of 400 mm. The residual pressure in the working chamber was maintained 5·10−5 mm Hg. The parameters of the irradiation regime are the following: energy - 5 keV, dose - 1018 ion/cm2, temperature - 200 °C. The strength characteristics were studied by the methods of measuring microhardness, residual voltage in the surface layers of implanted samples. A micro X-ray diffraction analysis was also performed.

Observation of room temperature ferromagnetism and exchange bias in a 55Mn+ ion-implanted unintentionally doped [formula omitted]-[formula omitted] single crystal

In this manuscript, the structural and magnetic properties of a 55Mn+ ion-implanted unintentionally doped β-Ga2O3 single crystal are investigated. The implanted Mn+ ions cause crystalline degeneration due to the formation of defects in the surface of the substrate. Room temperature ferromagnetism (FM) is observed in the samples with implantation doses of 5 × 1014cm-2, 1 × 1015cm-2 and 5 × 1015cm-2. The zero-field-cooled (ZFC)/field-cooled (FC) measurement of magnetization reveals that the ion implantation process induces an antiferromagnetic (AFM) phase. The temperature evolution of the remanence asymmetry (ME) demonstrates the typical behavior of the exchange bias effect due to the coexistence of FM and AFM phases. Based on the distribution of Mn+ ions and defects and the relationship between the remanence asymmetry (ME) and the exchange bias field (HE), the single domain and core-shell models are used to investigate the exchange bias system. The formation mechanism of the ferromagnetic order is briefly discussed, which is rather different from the one corresponding to the bound magnetic polaron (BMP) model.

Bi-doped silica glass: A combined XPS – DFT study of electronic structure and pleomorphic imperfections

The results of X-ray photoelectron spectroscopy analysis (core-levels, valence band) and first-principles modelling of bismuth implanted silicon dioxide electronic structure at various Bi-concentrations are reported. Most attention is paid to the study of Bi–O–Si chemical linkages and theoretically derived scenarios of Bi-embedding into SiO2 host-matrix. XPS analytics performed demonstrates the presence of spectral features related both with bismuth-bismuth and pleomorphicaly stretched bismuth-oxygen (Bi/O⋯Si–O) bonds fabrication at lowest employed pulsed-periodical Bi-ion fluence 5 × 1016 cm−2. The latter provides pleomorphic spectral separation of oxygen 2s band into O(I) 2s and O(II) 2s sub-bands. It was found that bismuth pairs of stoichiometric and nonstoichiometric (interstitial) impurities are responsible for that. Further increase in ion fluence up to 3 × 1017 cm−2 yields, in the main, the growth of α-Bi2O3-like frameworks within the volume of initial amorphous SiO2-host what have been interpreted as an appearance of stoichiometric Bi-impurity pairs. The results obtained well agree with our previous investigations of electronic structure of Bi-doped oxide host-matrices and theoretical MD-Tersoff third-party data. New approach toward modelling realistic process of ion-implantation was proposed and discussed.

Technological Sensor on Coupled Radial Spirals

We present the sensor with a sensitive element (SE) based on coupled radial spirals, which can be used for monitoring technological processes in the Electronic Industry, as well as for detecting damages on the pipelines under protective coatings. The main properties and characteristics of such SE are analyzed and measured. It is shown that the concentration of the electromagnetic field in a measuring space, caused by slowing down of the the wave, and splitting of the electric and magnetic fields leads to a significant increase in sensitivity, whereas the multiple increases in the slowdown makes it possible to use the advantages of SE with distributed parameters at relatively low operating frequencies. The practical realization of the described sensor is demonstrated in measuring the ion implantation processes and the thickness of the metallization, as well as in monitoring the invisible cracks and damages through the protective coats on the metal surfaces.

Molecular Dynamics Simulations of Vacancy Generation and Migration near a Monocrystalline Silicon Surface during Energetic Cluster Ion Implantation

The process of ion implantation often involves vacancy generation and migration. The vacancy generation and migration near a monocrystalline silicon surface during three kinds of energetic Si35 cluster ion implantations were investigated by molecular dynamics simulations in the present work. The patterns of vacancy generation and migration, as well as the implantation-induced amorphous structure, were analyzed according to radial distribution function, Wigner–Seitz cell, and identify diamond structure analytical methods. A lot of vacancies rapidly generate and migrate in primary directions and form an amorphous structure in the first two picoseconds. The cluster with higher incident kinetic energy can induce the generation and migration of more vacancies and a deeper amorphous structure. Moreover, boundaries have a loading–unloading effect, where interstitial atoms load into the boundary, which then acts as a source, emitting interstitial atoms to the target and inducing the generation of vacancies again. These results provide more insight into doping silicon via ion implantation.

Inhibition of stress corrosion cracking in 304 stainless steel through titanium ion implantation

The effects of titanium ion implantation on the stress corrosion cracking (SCC) behaviour of 304 austenitic stainless steel were studied. Slow strain rate tests (SSRTs) were conducted on 304 steel in air and in 5 wt-% NaCl solution. The microscopic effects of ion implantation were evaluated by Stopping and Range of Ions in Matter Procedures (SRIM). Fracture morphologies and microstructures were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The fracture surfaces illustrate that ion implantation significantly inhibits the corrosion pits that initiate SCC. A dense passive film, which inhibits SCC, was formed during the ion implantation process. SCC initiation was restrained due to the dense dislocation nets that were generated by titanium ion implantation.HighlightsIon implantation inhibits SCC susceptibility.The lack of Cr at the grain boundary leads to the expansion of SCC along the grain boundary.Implantation-induced damage leads to high-density dislocations.The surface was amorphised due to high-density dislocations.

Demonstration of 1200 V/1.4 mΩ cm2 vertical GaN planar MOSFET fabricated by an all ion implantation process

We present a vertical GaN planar metal-oxide-semiconductor field-effect transistor (MOSFET) fabricated by an all ion implantation process. The fabricated MOSFET shows an on-resistance of 2.78 mΩ cm2 and a breakdown voltage of 1200 V, by applying the short cell pitch design to reduce the on-resistance and a Mg and N sequential implantation to improve the breakdown voltage of the pn-junction. By evaluating each on-resistance component in the fabricated vertical GaN planar MOSFET using the simultaneously formed test structures, an effective on-resistance of the active region excluding the source parasitic resistance is 1.4 mΩ cm2. Consequently, it was demonstrated that an all ion implantation process can fabricate a vertical GaN planar MOSFET with a high breakdown voltage and low on-resistance. This result will greatly contribute to the realization of GaN power devices.

Investigation the Effect of Soft X-ray Flash Exposure on PN Diode

In this paper will present the properties of PN diode before and after expose by radiation. Although, radiation help to improve the performance of semiconductor device but still has some damage in device structure. In previous article I have showed performance improve after expose by soft radiation. The device is exposed by low frequency X-ray radiation (soft radiation flash exposure: SRFE) technique with few second for several times. In principle of PN diode after fabrication will has defects from process such as ion implantation, doped and silicon wafer process. The results show temperature while SRFE expose on device that generate high temperature on surface and silicon boundary that may the optimize energy and expose time for treatment damage of PN diode.

Improving the performance properties of titanium alloy VT6 after ion implantation with copper and aluminum ions

The objective of this work was to study the processes occurring on the surface of VT6 titanium alloy samples when implanting with copper and aluminum ions. Elemental composition, structural-phase state, mechanical and tribological properties of VT6 titanium alloy surface layers modified by aluminum and copper ions was being researched. As can be seen from the undertaken studies, the mode of high-intensity ion-implantation process makes it possible to obtain ion doped surface layers of VT6 alloy containing finely dispersed intermetallic phases and a solid solution of aluminum and copper in titanium of a composition varying in depth. The thickness of the ion-doped layer, the average grain size of the intermetallic phases and their conglomerates increases with the increase in implantation dose while aluminum implantation is in progress. It has been shown that the implantation of aluminum and copper ions into VT6 alloy leads to a considerable increase in its microhardness and wearability. Based on the research results, a conclusion on the positive effect of a structural-phase state of ion-doped titanium layers on their mechanical and tribological properties of VT6 titanium alloy has been drawn.