Influence Of Implantation Research Articles

Modification of microstructure, optical, and electrical properties in 180 keV Co and Fe implanted Al1.5Ga0.5O3 thin-films

We report the microstructure, optical and electrical properties of Al1.5Ga0.5O3 thin films implanted by 180 keV Fe and Co ions. The X-ray diffraction pattern confirmed rhombohedral structure with R 3‾ c space group for pristine and Fe-implanted films. The Co-implanted films showed amorphous structure. SRIM simulations suggested oxygen vacancy in the films. The atomic force microscopy confirmed the formation of spherical-shaped particles (17–20 nm) in Co-implanted GaAlO_Si_550 films. The RMS roughness of the GaAlO_Si_550 films increased from 19 nm to 25 nm at higher Co-ion implantation fluences. X-ray photoelectron spectroscopy supported the formation of oxygen vacancy and non-stoichiometry at surface of the films. Electrical conductivity of the films enhanced up to 10−2- 10−3 S/m by metallic Fe- and Co ion implantation. Optical band gap was found at ∼3.85 eV for GaAlO_Al_550 and ∼4.04 eV for GaAlO_Si_550 pristine films. Optical band gap was stabilized in the range of 3.75–4.52 eV for Fe- and Co-implanted films, which can be useful for opto-electronic device applications in the UV and deep blue region.

Optical and structural transformations in polyethylene terephthalate (PET) films subjected to Ag[formula omitted]-ion implantation and subsequent Au[formula omitted]-ion irradiation

We report on the dual effects of ion implantation and swift heavy ion on the optical and structural characteristics of polyethylene terephthalate (PET) films using UV–Vis spectrophotometry, FTIR and X-ray diffraction measurements. Samples were first implanted with 150 keV Ag+-ions at different fluences of 1 ×1016, 5 ×1016, and 1 ×1017 ions/cm2, and thereafter irradiated with 30 MeV Au7+-ions at different fluences, while analysing elemental depth profile in situ on the Time of Flight Heavy Ions Elastic Recoil Detection (ToF-Hi-ERDA) instrument. The elemental depth profile measurements showed considerable atomic depletion of hydrogen from 36% down to below 6% and oxygen from 18% to about 5%. The proportion of carbon increased from 45% to over 87%. The optical bandgap decreased with increasing ion implantation fluence and reduced even further on irradiation with 30 MeV 197Au7+-ions. The most notable outcome of the implantation was the onset of the precipitation of gold nanoparticles (Au-NPs) in the PET matrix, marked by Localised Surface Plasmon Resonance effects, coincided with a relatively significant drop in the bandgap energy. This latter effect could only be best explained as the result of these Au-NPs in the PET. This suggests that optical bandgap tuning in polymer films, usually achievable through high fluence implantation at low energy (i.e., keV), could also be realized through low fluence irradiation with MeV energy ions. It is surmised that, for the noble metals, NP-induced bandgap modification in PET precludes the need for high fluence to achieve the same. This has the obvious advantage of bandgap alterations at much lower structural damage to the target polymer. As reported by FTIR results, one can observe structural changes with the formation of new chemical bonds on thin films. X-ray diffraction results exhibited one prominent peak corresponding to the (100) plane, which varies in intensity with increased implantation fluence, suggesting a change in the crystallinity of the PET. The decrease in (100) peak or crystallinity was well connected with the presence and decrease of 847, 970, and 1471 cm−1 peaks, which were assigned to the ethylene glycol molecular groups.

Damage kinetics in high-temperature irradiated Ni crystals

High-temperature (∼800 K) ion irradiation with 380 keV Ar ions was used to modify the surface of Ni single crystals in order to generate radiation defects and mimic the effect of neutrons avoiding sample activation. The modified 800 nm thick layer was analyzed regarding structural and mechanical properties utilizing a combination of experimental and simulation techniques. The ion implantation fluence ranged from 1 × 1014 cm−2 up to 1 × 1016 cm−2, which corresponds to values of displacements per atom from 0.25 to 25, respectively. The structural characterization was performed by Rutherford Spectroscopy in Channeling mode (RBS/C) associated with scanning (SEM) and transmission electron microscopy (TEM). The experimental results were supported by Monte Carlo (McChasy) and Molecular Dynamics (MD-LAMMPS) simulations. The simulations performed using the second generation of the McChasy code show that the influence of bubbles formed inside the material is not negligible and affects the quantitative analysis of defects in the simulated spectra. A second step in damage kinetics was revealed for the highest dose (i.e., 25 dpa) as a consequence of the entanglement of dislocations and agglomeration of noble gas bubbles, which was confirmed by TEM analysis. Moreover, nanomechanical results confirm that Ar bubbles deteriorate mechanical properties such as hardness.

Novel ion beam implantation of felt electrodes for the vanadium flow battery: Role of defects versus nitrogen groups for the VO2+/VO2+ redox reaction

A novel approach to introduce catalytic sites to carbon and graphite felts in order to improve electrode activity and investigate the effectiveness of specific active sites for the vanadium flow battery (VFB) has been achieved via ion beam implantation. Here, both N2+ and Ne+ implantation is used to show that the positive vanadium (VO2+/VO2+) redox reaction preferentially occurs at the introduced defect sites, and not nitrogen-containing groups. This is shown through short charge and discharge tests and electrochemical impedance spectroscopy, with the electrodes characterised via X-ray photoelectron and Raman spectroscopies. Lower implantation fluences (1 × 1014–4 × 1015 ion cm−2) were shown to improve the pristine electrodes due to the formation of defect sites. However, implantation at higher fluences (above 4 × 1015 ion cm−2) resulted in a decrease in defect density, and a layer of amorphous carbon at the electrode surface was thought to hinder the redox reaction due to lower surface conductivity and less available active sites. This new approach of felt electrode modification shows that nitrogen-containing groups are not necessary for the positive vanadium redox reaction and shows the importance of defect engineering of electrodes for the VFB.

Surface blistering and D desorption in high-energy-rate forging W, W-Y2O3, W-TiC exposed to deuterium plasma

Pure tungsten (W) and two representative W alloys of W-1 wt.%Y2O3 and W-0.5 wt.%TiC were subjected to deuterium (D) plasma exposure at a fluence up to 1 × 1026 D/m2 at 400 K to evaluate their surface blistering and D desorption behaviors. Thermal desorption spectroscopy (TDS) results revealed that high-temperature desorption peaks (> 650 K) dominated in HERF-W, whereas the two W alloys featured higher intensities of low-temperature D desorption peaks (< 650 K). Even at a low D implantation fluence of 5 × 1023 D/m2, extensive blisters were evident on the surface of pure W, while no discernible blisters were detected on the surface of W-1 wt.%Y2O3 and W-0.5 wt.%TiC, even with a fluence exceeding 2 × 1025 D/m2. Microstructure analysis indicated that the relatively large grain size and limited intrinsic defects in HERF-W were the primary reasons for the early formation of D-induced blisters and subsequent high-temperature desorption of these trapped D, compared to those of two other W alloys. A focus ion beam (FIB)-SEM technique was employed to explore the mechanisms of blistering. Results revealed that the cavities beneath blisters were primarily located along grain boundaries, and coarse blisters were formed by the merging of several small ones. This work provides insight into the relationships among material microstructures, D-induced blistering and D desorption in W-based materials, thus offering valuable guidance for the design of W materials with high resistance to D-induced damages.

Fabrication of quantum emitters in aluminum nitride by Al-ion implantation and thermal annealing

Single-photon emitters (SPEs) within wide-bandgap materials represent an appealing platform for the development of single-photon sources operating at room temperatures. Group III-nitrides have previously been shown to host efficient SPEs, which are attributed to deep energy levels within the large bandgap of the material, in a configuration that is similar to extensively investigated color centers in diamond. Anti-bunched emission from defect centers within gallium nitride and aluminum nitride (AlN) have been recently demonstrated. While such emitters are particularly interesting due to the compatibility of III-nitrides with cleanroom processes, the nature of such defects and the optimal conditions for forming them are not fully understood. Here, we investigate Al implantation on a commercial AlN epilayer through subsequent steps of thermal annealing and confocal microscopy measurements. We observe a fluence-dependent increase in the density of the emitters, resulting in the creation of ensembles at the maximum implantation fluence. Annealing at 600 °C results in the optimal yield in SPEs formation at the maximum fluence, while a significant reduction in SPE density is observed at lower fluences. These findings suggest that the mechanism of vacancy formation plays a key role in the creation of the emitters and open enticing perspectives in the defect engineering of SPEs in solid state.

Evolution of Au nanoparticles in c-plane GaN under the heavy ion implantation and their optical properties

The modification of GaN with Au nanoparticles is a promising way for manipulating optical properties in optoelectronics and enhancing the sensitivity of GaN-based substrates used in Surface Enhanced Raman Spectroscopy. Ion implantation is an attractive method for the preparation of high-purity metal nanoparticles on the surface or within the bulk of solids, although this process in crystals is not yet fully understood. Here we study the specific stages of Au nanoparticle formation in c-plane GaN crystals implanted with 1.85 MeV Au ions to the fluence range of 1.5×1016 - 7×1016 cm−2. The implanted samples were annealed at 800 °C in an ammonia atmosphere for 20 minutes to support the nucleation of Au nanoparticles and prevent surface decomposition. The structural and optical properties of the samples were investigated by a combination of Rutherford backscattering spectroscopy in channeling mode (RBS-C), Transmission Electron Microscopy (TEM), Raman spectroscopy, photoluminescence (PL) and diffuse-reflectance spectroscopy (DRS). The two damaged regions, namely at the depth and at the surface, were identified. The depth region exhibits saturation of damage, unlike the surface region reaching an amorphous state for the highest implantation fluence. RBS-C revealed multimodal Au depth profiles for higher ion fluences, which were subsequently redistributed after thermal annealing due to the formation of Au nanoparticles, as confirmed by TEM. Au nanoparticles with fcc structure have been successfully synthesized with the Au-ion implantation fluence of 5×1016 cm−2 with the sizes mostly of 4 – 20 nm resulting in increased optical scattering and absorption within the spectral range of 500 – 700 nm associated with surface plasmon resonance (SPR) and the emergence of blue (2.8 eV) and red (2 eV) photoluminescence bands linked to the combined effect of SPR and implantation-induced defects.

Spin-State Control of Shallow Single NV Centers in Hydrogen-Terminated Diamond.

The ability to control the charge and spin states of nitrogen-vacancy (NV) centers near the diamond surface is of pivotal importance for quantum applications. Hydrogen-terminated diamond is promising for long spin coherence times and ease of controlling the charge states due to the low density of surface defects. However, it has so far been challenging to create negatively charged single NV centers with controllable spin states beneath a hydrogen-terminated surface because atmospheric adsorbates that act as acceptors induce surface holes. In this study, we optically detected the magnetic resonance of shallow single NV centers in hydrogen-terminated diamond through precise control of the nitrogen implantation fluence. Furthermore, we found that the probability of detecting the resonance was enhanced by reducing the surface acceptor density through passivation of the hydrogen-terminated surface with hexagonal boron nitride without air exposure. This control method opens up new opportunities for using NV centers in quantum applications.

A systematic investigation of structural and optical properties of Li ion implanted MgTiO3 thin films

Effects of lithium (Li) ions implantation on structural, optical, and luminescent properties of MgTiO3 (MTO) thin films were investigated in the present report. The films were initially deposited at a substrate temperature of 200 °C, which were then annealed at 700 °C for crystallization. Crystalline MTO films were implanted with 30 keV Li ions at various fluences ranging from 1 × 1014 to 1 × 1015 ions/cm2. The crystallinity of films decreases upon Li ions implantation at a fluence of 1 × 1014 ions/cm2. In contrast, a further increase in fluence to 1 × 1015 ions/cm2 results in an improvement in crystallinity. Annealed and implanted films show lesser transmittance than the as-deposited films. As-deposited film exhibits a bandgap of 3.79 eV, which increases to 4.28 eV upon annealing the films. Subsequently, with an increase in implantation fluence, the shrinkage in optical bandgap from 4.26 to 4.09 eV is observed. Moreover, the annealed films exhibit a refractive index of ∼2.2 which is higher as compared to as-deposited and implanted MTO samples. X-ray photoelectron spectroscopy was carried out to investigate the surface states related to Mg, Ti, and O in the samples and to analyze the variation of defects’ concentration with implantation. MTO thin films show luminescent centres in near ultraviolet and visible region. The annealing results in the enhancement of photoluminescence intensity which decreases on implantation, and a drastic quenching of intensity was observed at a fluence of 1 × 1015 ions/cm2. The average decay lifetime of as-deposited film is 9.1 ns. Annealing results in an increase in the average decay lifetime, while implantation leads to the reduction of average decay lifetime of MTO films.

Radiation damage evolution in High Entropy Alloys (HEAs) caused by 3–5 MeV Au and 5 MeV Cu ions in a broad range of dpa in connection to mechanical properties and internal morphology

High Entropy Alloys (HEAs) are prospective materials for nuclear fusion reactors and were irradiated in this study at a broad range of energetic ion fluences. Different ion masses (Cu and Au ions) and energies (3 and 5 MeV) were selected to investigate dpa (displacement per atom) development, radiation defect accumulation based on prevailing collision processes (Au ions) and ionization processes (Cu ions) in various HEAs. The studied HEAs differ in terms of elemental composition, internal morphology (grain structure) and other modifiers. Dpa values of 1 to ∼66 were achieved at Cu and Au ion fluences from 4 × 1014 to 1.3 × 1016 ions.cm−2 at room temperature, which generated varying levels of lattice damage. Theoretical simulations were performed to estimate the energy stopping and dpa depth distribution using SRIM code and compared with Au-concentration depth profiles determined by Rutherford backscattering spectrometry for Au-ions with 3 MeV ion energy. The prevailing energy losses of ions via ionization processes for Cu-5 MeV ions were found to increase the damage through lattice strain and probable lattice distortion, although the main defect introduction is expected to occur via collisions during nuclear stopping. Structural modification and defect accumulation were investigated by positron annihilation spectroscopy (PAS), which revealed a broader damaged layer with defects, where HEA-Nb (NbCrFeMnNi) exhibited the least damage accumulation from chosen alloys with no strong relation to the Au-5 MeV ion implantation fluence, whereas strong defect accumulation was recorded in the Au-ion implanted Eurofer97 used for comparison and HEA-Co (CoCrFeMnNi). PAS analysis also allowed defect sizes to be determined as an additional structural characteristic. The observed trends were also confirmed by thermal property analysis, with a worsening of thermal effusivity recorded after the irradiation in HEA-Co and Eurofer97. The worsening of the thermal properties was confirmed by the layer thickness, where the layer identified by PAS was found to be broader than the SRIM theoretical predictions. Nanoindentation measurements confirmed less pronounced radiation hardening of HEA-Nb relative to that observed in HEA-Co and Eurofer97. Transmission Electron Microscopy (TEM) analysis revealed layer thicknesses in reasonable agreement with the dpa depth profiles. The thermal effusivity decreased in the surface-irradiated layer in all investigated samples, the least influenced material was HEA-Nb.

Gradual modification of the YSZ structures by Au ion implantation and high-energy Si ion irradiation

Gold nanoparticles (Au-NPs) were created in crystalline yttria-stabilized zirconia (YSZ). (100)-, (110)- and (111)-oriented YSZ samples were implanted by 1 MeV Au+ ions at room temperature and fluences ranging from 1.5 × 1016 cm−2 to 7.5 × 1016 cm−2. The prepared Au: YSZ structures were annealed at 1100 °C for 1 h on air to support the Au-NPs coalescence and YSZ structure recovery. Subsequent irradiation with the 10 MeV Si3+ ions with a fluence of 5.0 × 1014 cm−2 was performed to enable gradual modification of Au-NPs. Au-depth profiles and YSZ structure modification in the produced samples were analysed via Rutherford backscattering spectrometry in channelling mode (RBS-C) and X-ray diffraction (XRD). RBS-C showed the gold distributed in the region of about 50–300 nm below the YSZ surface. The disorder was accumulated in the region with Au-NPs and the concentration of the disorder increases as a function of ion implantation fluence. The Zr-disorder was partially decreased after the annealing, while the subsequent Si-ion irradiation increased Zr-disorder again, however, the disorder does not reach values before the annealing. XRD measurement evidenced elastic deformation of the YSZ host lattice in the Au-implanted samples. Optical absorbance showed the appearance of the new absorption band at 550 nm for the Au-ion fluences above 5.0 × 1016 cm−2 ascribed to the Au-NPs formation. After the annealing, the absorption band is shifted to the wavelength of 580 nm which could be connected to the proceeding clustering of Au. The maximum absorption peak intensity increases which is connected to the increasing amount of the Au-NPs. Transmission electron microscopy (TEM) with Energy dispersive spectroscopy (EDS) confirmed the presence of Au-NPs in the implanted layer after the annealing. The subsequent Si-ion irradiation did not change the Au-NP shape which remained spherical with a slight size increase.

The catalytic, sensory and electrical properties of GO, PI and PLLA implanted by low-energy copper ions

In this work, we focused on ion beam modification and doping of graphene oxide (GO), polylactic acid (PLLA) and polyimide (PI) by low-energy Cu ions for a study of catalytic, sensory and electrical properties. We implanted the GO and polymer samples with 20 keV Cu ions with three implantation fluences from 3.75 × 1012 cm−2 to 1.0 × 1016cm−2. As follows, the elemental composition and structural changes were studied using Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Rutherford Back-scattering Spectroscopy (RBS) and Elastic Recoil Detection Analysis (ERDA). The surface morphology was analysed using Atomic Force Microscopy (AFM). The electrical properties of prepared structures were characterized by 2-point sheet resistivity measurement and the sensory properties were analysed in an atmospheric chamber and compared with BME280 combined humidity/temperature/pressure sensor. The photo-catalytic properties were studied by Rhodamine-B disintegration under UV light. Ion beam implantation has been applied successfully to the functionalization of used samples. The electrical conductivity increased with increasing Cu ion fluence. The GO and PI demonstrated effective sensory and photo-catalytic performance and the best result was achieved for Cu ion fluence of 3.75 × 1012 cm−2.

Study of surface morphology in GaAs by hydrogen and helium implantation at elevated temperature

In this work, the surface morphology and internal defect evolution process of GaAs substrates implanted with light ions of different fluence combinations are studied. The influence of H and He ions implantation on the atomic mechanism of the blister phenomenon observed after annealing is investigated. Raman spectroscopy is used to measure the surface stress change of different samples before and after implantation and annealing. Optical microscopy and atomic force microscopy are used to characterize the morphology changes of the GaAs surface under different annealing conditions. The evolution of bubbles and defects in GaAs crystals is revealed by transmission electron microscopy. Through this study, it is hoped that ion implantation fluence, surface exfoliation efficiency and exfoliation cost can be optimized. At the same time, it also lays a foundation for the heterointegration of GaAs film on Si.

Structure-dependent optical properties of Au/Ag irradiated TiN thin films

Titanium nitride (TiN) is an attractive alternative for modern and future photonic applications, as its optical properties can be engineered over a wide spectral range. In this study, we have used sequential implantation of gold and silver ions with varying ion fluence, as well as subsequent annealing, in order to modify the optical and plasmonic properties of TiN thin films and correlated this to their structural properties. Our investigations show that the columnar structure of the TiN films is partially destroyed upon implantation, but metallic Au and Ag nanoparticles are formed. The irradiation further induces a reduction of the lattice constant as well as changes the TiN stoichiometry and grain size. From the optical point of view, the implanted films possess less metallicity with increasing Ag fluence and losses several times lower than the as-deposited film, which can be correlated with the deficiency of nitrogen and additional defects. Subsequent annealing partially recovered the destroyed columnar structure, and the films become more metallic where the optical losses are much smaller in comparison to the as-implanted situation, being comparable to those of pure Au and Ag. In this way, by varying the implantation fluence of silver ions properly while keeping the gold fluence constant, we were able to optimize experimental parameters in such a way to ensure the formation of TiN with desirable optical performances.

Defect structures as a function of ion irradiation and annealing in LiNbO3

Ion implantation is commonly utilized during the fabrication of lithium niobate (LiNbO3) acousto- and opto-electronic devices. Mechanistically, implantation creates material defects affecting properties that can be leveraged to create functionality. Enhancing scalability and the repeatability of these implantation protocols therefore necessitates linking process parameters of implantation with those defects created and ultimately the properties imparted by these defects. In response, we systematically examined the effects of ion species (H, He, and N), irradiation energy (150 keV to 2 MeV), implantation fluence (1 × 1012 to 1 × 1018 ions/cm2), and post-irradiation heat treatment (250 to 750 °C) in 128° Y-cut LiNbO3. The resulting defect structures were then analyzed via transmission electron microscopy and Raman spectroscopy. Defect formation suitable for fracture-based processes can be achieved with implantation of He ions, using an implantation fluence of 1 × 1018 ions/cm2 and a heat treatment at 250 or 500 °C. Other irradiation and annealing recipes that mimic material fabrication conditions show the defect evolution in LiNbO3 dependent on irradiation conditions.

Evaluation of argon ion impact parameters in aluminium oxide by means of SRIM program and investigation of the effect of argon ion implantation on the thermoluminescence properties aluminium oxide

The thermoluminescence properties of aluminium oxide (alumina) implanted with 80 keV argon ions at fluences in the range of were investigated. The unimplanted and implanted samples were irradiated at a dose of 40 Gy and heated at a rate of 1°C/s. The glow curve of unimplanted and implanted samples shows 5 distinct peaks; the main dosimetric peak and four other peaks of lower intensity. In this study, our analysis has focussed on the main dosimetric peak located at 180°C, 191°C, 177°C, 208°C, 219°C and 207°C for the unimplanted sample and implanted samples respectively. It was observed that the TL intensity decreases with fluence of implantation. This suggests that ion implantation decreases the concentration of electron traps responsible for thermoluminescence. It can also be suggested that competition effects involving radiative pathways and non-radiative competitor traps may lead to a low thermoluminescence signal in the implanted samples in comparison to the unimplanted thermoluminescence signal. These competitive processes will tend to favour first-order kinetics, and consequently lead to a strong stability of the glow curve shapes. The creation of defect clusters as well as extended defects could also be responsible for the reduction in TL signal. The stopping and range of atoms in matter (SRIM) was used to evaluate the ion impact parameters including ion range, vacancy distribution and energy loss in Al2O3. Subsequent to ion implantation, it was found that the number of oxygen vacancies which are related to electron traps are higher than the number of aluminium vacancies. Kinetic analysis was carried out by means of the initial rise, Chen’s peak shape, various heating rate, the whole glow curve, glow curve fitting and isothermal decay methods. The activation energy was found to be around and the frequency factor to be of the order regardless of the implantation fluence. The dosimetric features of samples were also investigated at doses in the range of 40–200 Gy. Samples generally showed a superlinear response at doses less than 140 Gy and sublinear response at doses higher than 160 Gy.

Combined Au/Ag nanoparticle creation in ZnO nanopillars by ion implantation for optical response modulation and photocatalysis

ZnO nanopillars were implanted with Au-400 keV and Ag-252 keV ions with ion fluences from 1 × 1015 cm−2 to 1 × 1016 cm−2. We compared ZnO nanopillars solely implanted with Au-ions and dually-implanted with Au and Ag-ions. Rutherford Back-Scattering spectrometry (RBS) confirmed Ag and Au embedded in ZnO nanopillar layers in a reasonable agreement with theoretical calculations. A decreasing thickness of the ZnO nanopillar layer was evidenced with the increasing ion implantation fluences. Spectroscopic Ellipsometry (SE) showed a decrease of refractive index in the nanopillar parts with embedded Au, Ag-ions. XRD discovered vertical domain size decreasing with the proceeding radiation damage accumulated in ZnO nanopillars which effect was preferably ascribed to Au-ions. SE and diffuse reflectance spectroscopy (DRS) showed optical activity of the created nanoparticles at wavelength range 500 – 600 nm and 430 – 700 nm for the Au-implanted and Au, Ag-implanted ZnO nanopillars, respectively. Photoluminescence (PL) features linked to ZnO deep level emission appear substantially enhanced due to plasmonic interaction with metal nanoparticles created by Ag, Au-implantation. Photocatalytic activity seems to be more influenced by the nanoparticles presented in the layer rather than the surface morphology. Dual implantation with Ag, Au-ions enhanced optical activity to a larger extent without significant morphology deterioration as compared to the solely Au-ion implanted nanopillars.

Divacancy and silicon vacancy color centers in 4H-SiC fabricated by hydrogen and dual ions implantation and annealing

Silicon carbide (SiC), as a wide-band gap semiconductor, plays an important role in high temperature and high-power devices, and the spin defect has great application prospect in quantum technology. Divacancy in SiC (VCVSi, VV) has attracted more and more attention. There are a lot of experimental studies on color center preparation by ion implantation, but the mechanism of atomic scale defects in the experimental preparation process is not fully understood. EPI epitaxial 4H–SiC was implanted with 250 keV proton at room temperature under three fluence of 1E14 cm−2, 1E15 cm−2, 1E16 cm−2. Defects of implanted 4H–SiC samples were characterized by photoluminescence spectrum and electron paramagnetic resonance (EPR). The existence of the optimal implantation fluence for VSi and VCVSi (VV) color centers by hydrogen ion implantation was found. Molecular dynamics (MD) simulation by considering the ionization energy loss for swift ion implantation were used to study the defect distribution and transformation at atomic-scale during hydrogen ion implantation and post-annealing. The optimal implantation fluence was found and confirmed by comparing the atomic-scale implantation simulation with the experimental results. In the annealing simulation, the optimal annealing temperature for the color centers in 4H–SiC was verified, and its formation mechanism was analyzed by accurately calculating the defect transformation during the annealing process. Finally, in order to accurately control the depth of color center in 4H–SiC, dual ions implantation of carbon and proton has been studied to realize the optimal divacancy yield by SRIM and MD simulations. Molecular dynamics simulation results showed that low-fluence C pre-implantation is helpful to improve the color center yield for the dual ions implantation.

Single G centers in silicon fabricated by co-implantation with carbon and proton

We report the fabrication of isolated G centers in silicon with single photon emission at optical telecommunication wavelengths. Our sample is made from a silicon-on-insulator wafer, which is locally implanted with carbon ions and protons at various fluences. Decreasing the implantation fluences enables us to gradually switch from large ensembles to isolated single defects, reaching areal densities of G centers down to ∼0.2 μm−2. Single defect creation is demonstrated by photon antibunching in intensity-correlation experiments, thus establishing our approach as an effective procedure for generating single artificial atoms in silicon for future quantum technologies.

Impact of ion implantation and annealing parameters on bifacial PERC and PERT solar cell performance

Passivated Emitter and Rear Contact (PERC) and Passivated Emitter Rear Totally Diffused (PERT) solar cell designs are now a market reality. In the production of these cells, ion implantation is another method for creating emitters and back surface field (BSF) regions, since it can facilitate the process flow and precise doping control. Here, Technology Computer Aided Design (TCAD) is utilized to assess the effects of ion implantation fluences, annealing temperature, and duration, on the performance of bifacial PERC solar cells. To ensure realistic simulation results, the solar cell model is developed using experimentally demonstrated bifacial counterparts. The process simulation models are also calibrated to match experimentally obtained doping profiles. Simulation results show that by replacing emitter diffusion with phosphorus ion implantation, both the front/rear efficiencies can be improved by 0.07%. The rear boron implantation is also optimized to provide an effective BSF, improving the front/rear efficiencies by 0.21/0.15%, respectively. Moreover, co-annealing of emitter and BSF regions exhibits a 0.2% increase in efficiency than separately annealed PERT cells. Hence an overall improvement of 0.48/0.42% is achieved in the front/rear efficiencies when compared to the original diffused emitter PERC design. The fabrication process sequence is also suggested for these solar cells.