Carbon Implantation Research Articles

A New Approach to Enhancing Radiation Hardness in Advanced Nuclear Radiation Detectors Subjected to Fast Neutrons

Low-Gain Avalanche Diodes (LGADs) are critical sensors for the ATLAS and CMS timing detectors at the High Luminosity Large Hadron Collider (HL-LHC), offering enhanced timing resolution with gain factors of 20 to 50. However, their radiation tolerance is hindered by the Acceptor Removal Phenomenon (ARP), which deactivates boron in the gain layer, reducing gain below the threshold for accurate timing. This study investigates the radiation hardness of thin, carbon-doped LGAD sensors developed by Brookhaven National Laboratory (BNL) to address ARP-induced limitations. Active dopant profiles in the gain layer, junction, and bulk were measured using a Spreading Resistance Probe (SRP) profilometer, and the effects of annealing and neutron irradiation at fluences of 3 × 1014, 1 × 1015, and 3 × 1015 neq/cm2 (1 MeV equivalent) were analyzed. Low carbon dose rates showed minimal improvement due to enhanced deactivation, while higher doses improved radiation hardness, demonstrating a non-linear dose–response relationship. These findings highlight the potential of optimizing gain layers with high carbon doses and low-diffusion boron to extend LGAD lifetimes in high-radiation environments. Future research will refine carbon implantation strategies and explore alternative approaches to further enhance the radiation hardness of LGADs.

Biocompatibility of boron-enriched pyrolitic carbon

The Institute for Nuclear Problems of the Belarusian State University (INP BSU) has developed equipment and optimized the technology for synthesizing boron-doped pyrocarbon, a material for application in heart valve endoprostheses.The purpose of this work was to evaluate the general and biochemical blood tests, mass coefficients of animal organs and the dynamics of reactions of rat tissues to implantation of pyrocarbon material in the subcutaneous tissues of the interscapular region. Animals were monitored for 90 days. According to the morphometric data, the boron-doped pyrocarbon, synthesized in INP BSU, was found to be non-irritating to the tissue in comparison with the control sample during all periods of observation. There was no significant effect of implantation of pyrolytic carbon on the parameters of the blood general and biochemical analysis in rats compared with healthy animals. The results of necropsy showed that the mass of organs and mass coefficients of animals did not deviate from the physiological norm during different periods of pyrocarbon sample implantation.Thus, the boron-doped pyrocarbon material synthesized in INP BSU can be used for manufacturing heart valve endoprostheses.

Competitive Intracellular Hydrogen-Nanocarrier Among Aluminum, Carbon, or Silicon Implantation: a Novel Technology of Eco-Friendly Energy Storage using Research Density Functional Theory

Competitive Intracellular Hydrogen-Nanocarrier Among Aluminum, Carbon, or Silicon Implantation: a Novel Technology of Eco-Friendly Energy Storage using Research Density Functional Theory

Molecular dynamics simulation study of nitrogen vacancy color centers prepared by carbon ion implantation into diamond

Nitrogen vacancy (NV) color centers in diamond have useful applications in quantum sensing and fluorescent marking. They can be generated experimentally by ion implantation, femtosecond lasers, and chemical vapor deposition. However, there is a lack of studies of the yield of NV color centers at the atomic scale. In the molecular dynamics simulations described in this paper, NV color centers are prepared by ion implantation in diamond with pre-doped nitrogen and subsequent annealing. The differences between the yields of NV color centers produced by implantation of carbon (C) and nitrogen (N) ions, respectively, are investigated. It is found that C-ion implantation gives a greater yield of NV color centers and superior location accuracy. The effects of different pre-doping concentrations (400–1500 ppm) and implantation energies (1.0–3.0 keV) on the NV color center yield are analyzed, and it is shown that a pre-doping concentration of 1000 ppm with 2 keV C-ion implantation can produce a 13% yield of NV color centers after 1600 K annealing for 7.4 ns. Finally, a brief comparison of the NV color center identification methods is presented, and it is found that the error rate of an analysis utilizing the identify diamond structure + coordination analysis method is reduced by about 7% compared with conventional identification methods.

Optimizing energy storage: Carbon implantation in NiO matrix unveils C–NiO's hybrid capacitive and battery-like behavior with enhanced electrochemical performance

Doping is a common strategy employed to enhance material properties. Numerous researchers have introduced carbon into the nickel oxide (NiO) matrix through various methods to improve the electrochemical performance for energy storage applications. This study investigates the impact of carbon implantation into the NiO matrix using a particle accelerator. Cyclic voltammetry profiles of carbon-implanted NiO (C–NiO) reveal distinct oxidation–reduction peaks, and one side of the CV curves exhibits a rectangular shape, confirming the hybrid capacitive and battery-like behavior of C–NiO. The reduced separation between oxidation–reduction peaks and the increased specific capacitance at higher scan rates validate the capacitive nature of C–NiO. Enhanced electrochemical performance was further explored through GCD, EIS, and BET techniques. C–NiO demonstrates impressive capacitance retention of 93.8 % after 5000 cycles. The Nyquist plot indicates that the improved performance of C–NiO is attributed to its heightened electrode activity, resulting from lower charge-transfer resistance. BET analysis confirms that C-doping leads to a larger surface area. In the NiO matrix, two bands of adsorbed CO2 are observed, whereas these bands are absent in C–NiO, indicating clearer pathways for ion–electron exchange. Compared to undoped NiO (55 F/g at 50 mV/s), C–NiO exhibits a more than tenfold increase in specific capacitance (1079 F/g at 50 mV/s).

Carbon-Related Quantum Emitter in Hexagonal Boron Nitride with Homogeneous Energy and 3-Fold Polarization.

Most hexagonal boron nitride (hBN) single-photon emitters (SPEs) studied to date suffer from variable emission energy and unpredictable polarization, two crucial obstacles to their application in quantum technologies. Here, we report an SPE in hBN with an energy of 2.2444 ± 0.0013 eV created via carbon implantation that exhibits a small inhomogeneity of the emission energy. Polarization-resolved measurements reveal aligned absorption and emission dipole orientations with a 3-fold distribution, which follows the crystal symmetry. Photoluminescence excitation (PLE) spectroscopy results show the predictability of polarization is associated with a reproducible PLE band, in contrast with the non-reproducible bands found in previous hBN SPE species. Photon correlation measurements are consistent with a three-level model with weak coupling to a shelving state. Our ab initio excited-state calculations shed light on the atomic origin of this SPE defect, which consists of a pair of substitutional carbon atoms located at boron and nitrogen sites separated by a hexagonal unit cell.

Characterization of the response of IHEP-IME LGAD with shallow carbon to Gamma Irradiation

Low Gain Avalanche Detectors (LGAD) for the High-Granularity Timing Detector (HGTD) are crucial in reducing pileups in the High-Luminosity Large Hadron Collider. Numerous studies have been conducted on the bulk irradiation damage of LGADs. However, few studies have been carried out on the surface irradiation damage of LGAD sensors with shallow carbon implantation. In this paper, the IHEP-IME LGADs with shallow carbon implantation were irradiated up to 2 MGy using gamma irradiation to investigate surface damage. Important characteristic parameters, including leakage currents, breakdown voltage (BV), inter-pad resistances, and capacitances, were tested before and after irradiation. The results showed that the leakage current and BV increased after irradiation, whereas overall inter-pad resistance exhibited minimal change and remained above 109 Ω before and after irradiation. Capacitance was found to be less than 4.5 pF with a slight decrease in the gain layer depletion voltage (V gl ) after irradiation. No parameter affected by the inter-pad separation was observed before and after irradiation. All characteristic parameters meet the requirements of HGTD, and this design can be used to further optimization.

Amine-impregnated porous carbon–silica sheets derived from vermiculite with superior adsorption capability and cyclic stability for CO2 capture

Amine-functionalized adsorbents have become one of the most promising capture technologies for greenhouse gas mitigation. However, developing cost-effective adsorbents with high adsorption capacity and superior cyclic stability via temperature swing adsorption remains difficult. Herein, sandwich-like polyethyleneimine (PEI)-impregnated porous carbon–silica sheets derived from vermiculite (AEVCP) adsorbents were successfully synthesized via porous carbon network confined within acid activated expanded vermiculite derived silica (AEV) sheets and interlayer amine-functionalization with PEI impregnation. The effect of adsorption temperature on CO2 adsorption performances, adsorption/desorption kinetics and thermodynamics for AEVCP adsorbents were specifically discussed. The optimal AEVCP50 adsorbent possessed a large CO2 uptake of 1.84 mmol/g at 75 ℃ in 60 vol% CO2/40 vol% N2 and superior cyclic stability with 7.6 % decay after 10 cycles, due to the hierarchical porous structure and high thermal conductivity of porous carbon–silica sheets derived from vermiculite (AEVC) support. The unique sandwich-like features of AEVC support are favorable for the high amine loading, rapid CO2 diffusion and efficient capture. The interlayer carbon implantation and amine-functionalization with strong interlayer spatial confinement effect, can suppress the formation of urea linkages, avoid the persistent over-heating and excess amine agglomeration, and enhance the gas diffusion and thermal transfer during the adsorption isobar process, which ultimately lead to superior adsorption capability and cyclic stability for CO2 capture. This design approach of cost-effective adsorbents derived from natural minerals provides a new avenue for practical CO2 capture and separation processes.

Scalable manufacturing of quantum light emitters in silicon under rapid thermal annealing.

Quantum light sources play a fundamental role in quantum technologies ranging from quantum networking to quantum sensing and computation. The development of these technologies requires scalable platforms, and the recent discovery of quantum light sources in silicon represents an exciting and promising prospect for scalability. The usual process for creating color centers in silicon involves carbon implantation into silicon, followed by rapid thermal annealing. However, the dependence of critical optical properties, such as the inhomogeneous broadening, the density, and the signal-to-background ratio, on centers implantation steps is poorly understood. We investigate the role of rapid thermal annealing on the dynamic of the formation of single color centers in silicon. We find that the density and the inhomogeneous broadening greatly depend on the annealing time. We attribute the observations to nanoscale thermal processes occurring around single centers and leading to local strain fluctuations. Our experimental observation is supported by theoretical modeling based on first principles calculations. The results indicate that annealing is currently the main step limiting the scalable manufacturing of color centers in silicon.

PMOS junction optimization for 3D NAND FLASH memory with CMOS under array

Continuous scaling the 3D NAND technology from CMOS Near Array (CNA) to CMOS Under Array (CUA) can achieve a minimal cell footprint and die size. However, the CMOS performance needs to overcome the short channel effect (SCE) and dopant deactivation since the thermal budget of the array cell would be fully executed on the CMOS transistor when 3D NAND architecture changes from CNA to CUA. Applying Cryogenic technology and carbon co-implantation can boost the CMOS performance by reducing implant induced defects in end of range (EOR) and controlling the interstitials to minimize dopants, such as boron or phosphorus, transient enhanced diffusion (TED) during subsequent thermal process. In this paper, using cold carbon implantation on P-type MOS S/D extension and P-type plug contact process of 96 layer 3D NAND FLASH memory with CUA structure can improve the device characteristics when decreasing the gate length and distance of the poly to contact, such as less SCE and better device On/Off performance. Besides, junction variability improvement is also demonstrated.

Controlling the beam angle spread of carbon implantation for improvement of bin map defect in V-NAND flash memory

As the shrinkage of devices accelerates and the vertical layers increase, beam angle spread of carbon ion implantation (C IIP) for the silicon selective epitaxial growth (Si-SEG) areas in V-NAND is one of the most critical parameters related with bin map defects. The roles of C IIP in Si-SEGs are that it can suppress channeling effect of boron IIP and diffusion limitation of boron dopants during subsequent annealing processes. In this study, beam angle spread was reduced by 36% and the center-to-edge beam angle skew of wafer was reduced to less than 1° by optimizing the specification of tracking magnet and the beam angle mean. After applying the improved process conditions and effective interlocks, the bin defective rate was controlled less than 0.5% successfully.

Spectrally stable nitrogen-vacancy centers in diamond formed by carbon implantation into thin microstructures

The nitrogen-vacancy center (NV) in diamond, with its exceptional spin coherence and convenience in optical spin initialization and readout, is increasingly used both as a quantum sensor and as a building block for quantum networks. Employing photonic structures for maximizing the photon collection efficiency in these applications typically leads to broadened optical linewidths for the emitters, which are commonly created via nitrogen ion implantation. With studies showing that only native nitrogen atoms contribute to optically coherent NVs, a natural conclusion is to either avoid implantation completely or substitute nitrogen implantation by an alternative approach to vacancy creation. Here, we demonstrate that implantation of carbon ions yields a comparable density of NVs as implantation of nitrogen ions and that it results in NV populations with narrow optical linewidths and low charge-noise levels even in thin diamond microstructures. We measure a median NV linewidth of 150 MHz for structures thinner than 5 μm, with no trend of increasing linewidths down to the thinnest measured structure of 1.9 μm. We propose a modified NV creation procedure in which the implantation is carried out after instead of before the diamond fabrication processes and confirm our results in multiple samples implanted with different ion energies and fluences.

Study of the Acceptor Removal Effect of LGAD

This article presents a detailed investigation of the influence of carbon co-implantation on the radiation hardness of the low gain avalanche detectors (LGADs). The implantation and thermal annealing of carbon during LGAD fabrication could improve the device’s radiation hardness. As an attempt to explain the mechanism of the implanted carbon to suppress acceptor removal induced by neutron irradiation, the acceptor removal coefficients ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$c$ </tex-math></inline-formula> factors) of LGADs are modeled based on secondary ion mass spectrometry (SIMS), which is used to study carbon and boron distributions in critical regions of LGADs. The model is in good agreement with the radiation hardness measurement of both sensors fabricated by the Institute of High Energy Physics (IHEP) and by others, revealing the reliability of the model in predicting the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$c$ </tex-math></inline-formula> factor without irradiating the sensors but with only density profiles of carbon and boron. This model is pivotal to the design of the next version of IHEP LGAD aiming at reaching better anti-radiation performance.

Design and testing of LGAD sensor with shallow carbon implantation

The low gain avalanche detectors (LGADs) are thin sensors with fast charge collection which in combination with internal gain deliver an outstanding time resolution of about 30 ps for Minimum Ionizing Particles (MIP). High collision rates and consequent large particle rates crossing the detectors at the upgraded Large Hadron Collider (LHC) in 2028 will lead to radiation damage and deteriorated performance of the LGADs. The main consequence of radiation damage is loss of gain layer doping (acceptor removal) which requires an increase of bias voltage to compensate for the loss of charge collection efficiency and consequently time resolution. The Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS) has developed a process based on the Institute of Microelectronics (IME), CAS capability to enrich the gain layer with carbon to reduce the acceptor removal effect by radiation. After 1 MeV neutron equivalent fluence of 2.5 × 1015 neq/cm2, which is the maximum fluence to which sensors will be exposed at ATLAS High Granularity Timing Detector (HGTD), the IHEP-IME second version (IHEP-IMEv2) 50μm LGAD sensors already deliver adequate charge collection >4 fC and time resolution <50 ps at voltages <400 V. The operation voltages of these 50μm devices are well below those at which single event burnout may occur.

A Combination of Ion Implantation and High‐Temperature Annealing: The Origin of the 265 nm Absorption in AlN

The commonly observed absorption around 265 nm in AlN is hampering the outcoupling efficiency of light‐emitting diodes (LEDs) emitting in the UV‐C regime. Carbon impurities in the nitrogen sublattice (CN) of AlN are believed to be the origin of this absorption. A specially tailored experiment using a combination of ion implantation of boron, carbon, and neon with subsequent high‐temperature annealing allows to separate the influence of intrinsic point defects and carbon impurities regarding this absorption. Herein, the presented results reveal the relevance of the intrinsic nitrogen‐vacancy defect VN. This is in contradiction to the established explanation based on CN defects as the defect causing the 265 nm absorption and will be crucial for further UV‐LED improvement. Finally, in this article, a new interpretation of the 265 nm absorption is introduced, which is corroborated by density functional theory (DFT) results from the past decade, which are reviewed and discussed based on the new findings.

Laminin Adsorption and Adhesion of Neurons and Glial Cells on Carbon Implanted Titania Nanotube Scaffolds for Neural Implant Applications.

Interfacing neurons persistently to conductive matter constitutes one of the key challenges when designing brain-machine interfaces such as neuroelectrodes or retinal implants. Novel materials approaches that prevent occurrence of loss of long-term adhesion, rejection reactions, and glial scarring are highly desirable. Ion doped titania nanotube scaffolds are a promising material to fulfill all these requirements while revealing sufficient electrical conductivity, and are scrutinized in the present study regarding their neuron-material interface. Adsorption of laminin, an essential extracellular matrix protein of the brain, is comprehensively analyzed. The implantation-dependent decline in laminin adsorption is revealed by employing surface characteristics such as nanotube diameter, ζ-potential, and surface free energy. Moreover, the viability of U87-MG glial cells and SH-SY5Y neurons after one and four days are investigated, as well as the material's cytotoxicity. The higher conductivity related to carbon implantation does not affect the viability of neurons, although it impedes glial cell proliferation. This gives rise to novel titania nanotube based implant materials with long-term stability, and could reduce undesirable glial scarring.

Direct graphene synthesis on LiNbO3 substrate by C implantation on Cu covering layer

We directly synthesized multi-layer graphene with an area of several hundred square microns on the lithium niobate (LN, LiNbO3) substrate by Carbon (C) implantation into the copper (Cu)-covered LiNbO3. The energy of C ion implantation was optimized per SRIM simulation to ensure that the distribution of C covers the Cu/LiNbO3 interface. The optimized energy was established at 55 keV, such that the formation of C peaks in the respective materials on each side of the Cu/LiNbO3 interface. The diffusion of the accumulated C to the Cu/LiNbO3 interface can form a more uniform C distribution at the interface, which is beneficial to the synthesis of graphene. Following the annealing process and removal of the Cu coating, a multi-layer graphene with an area of several hundred square microns on the surface of LiNbO3 was identified and characterized using Scanning Electron Microscopy (SEM), Energy-Dispersive x-ray Spectroscopy (EDS), Raman spectroscopy, and Atomic Force Microscopy (AFM). This remarkable advancement encourages the industrialization of direct graphene synthesis on LiNbO3 substrates via ion implantation.

Tuning of gain layer doping concentration and Carbon implantation effect on deep gain layer

Next generation Low Gain Avalanche Diodes (LGAD) produced by Hamamatsu photonics (HPK) and Fondazione Bruno Kessler (FBK) were tested before and after irradiation with ~1MeV neutrons at the JSI facility in Ljubljana. Sensors were irradiated to a maximum 1-MeV equivalent fluence of 2.5E15 Neq/cm2. The sensors analysed in this paper are an improvement after the lessons learned from previous FBK and HPK productions that were already reported in precedent papers. The gain layer of HPK sensors was fine-tuned to optimize the performance before and after irradiation. FBK sensors instead combined the benefit of Carbon infusion and deep gain layer to further the radiation hardness of the sensors and reduced the bulk thickness to enhance the timing resolution. The sensor performance was measured in charge collection studies using β-particles from a 90Sr source and in capacitance-voltage scans (C-V) to determine the bias to deplete the gain layer. The collected charge and the timing resolution were measured as a function of bias voltage at -30C. Finally a correlation is shown between the bias voltage to deplete the gain layer and the bias voltage needed to reach a certain amount of gain in the sensor. HPK sensors showed a better performance before irradiation while maintaining the radiation hardness of the previous production. FBK sensors showed exceptional radiation hardness allowing a collected charge up to 10 fC and a time resolution of 40 ps at the maximum fluence.

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.

Influence of carbon on hydrogen retention in molybdenum for nuclear material application: A first-principles investigation

• Systematic DFT simulations for the effect of carbon on the H retention in Mo. • Impurity carbon cannot trap H atoms in perfect Mo. • Impurity carbon has little effect on the H vacancy capturing in Mo. • Mo-carbon layer prevents the H diffusion and permeation in Mo. Mo has been applied to nuclear material, in which H and carbon impurities are unavoidable. In view of this, we have studied the effect of carbon on the H retention in Mo using first-principles simulations. In perfect Mo, there is always repulsion between H and carbon, and impurity carbon cannot capture H atoms. With the appearance of vacancy in Mo, vacancy and carbon-vacancy cluster trap seven and six H atoms, respectively. This means that impurity carbon has little effect on the H vacancy capturing. Finally, we explore the H diffusion by considering the presence of one Mo-carbon layer in Mo. Away from the Mo-carbon layer, H jumps along the optimal route with a diffusion barrier of 0.12 eV. As H moves close and passes through the Mo-carbon layer, the H diffusion barrier is increased to 0.73 eV. Therefore, the repulsive interaction between H and carbon can increase the H energy barrier in the vicinity of the Mo-carbon layer, which prevent the H diffusion and permeation in Mo. The current results can explain the promoting mechanism of bubble formation due to impurity carbon implantation and help us design future Mo-based nuclear material.