Ion implantation as a production technique
Ion implantation process for producing N-P solar cells
SOLAR CELL↗
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Novel effects of grain size and ion implantation on grain boundary segregation in ion irradiated austenitic steel
Nuclear reactor environments are extreme in nature due to the combination of exposure to corrosive coolant, mechanical stresses, and neutron irradiation damage. This combination of environments can lead to irradiation induced/assisted precipitation, segregation, and embrittlement coupled with enhanced creep and stress corrosion cracking. While nanostructured materials are of interest in a variety of applications due to their unique properties including high mechanical strength, for nuclear applications nanostructured materials have the added benefit of irradiation resistance due to the high volume density of sinks for irradiation-induced defects. In this study, we show unique radiation-induced segregation (RIS) behavior in nanocrystalline 304 stainless steel (SS304). Typical RIS in austenitic steels includes Ni enrichment and Cr depletion within the grain boundaries. In nanostructured SS304 this RIS is reduced. Furthermore, interestingly, some grain boundaries in the nanocrystalline SS304 in this study were found to be enriched in Cr after Fe 2+ ion irradiation at 500 °C up to 50 displacements per atom (dpa). To understand this unique observation, lattice-based atomic kinetic Monte Carlo simulations were performed to investigate the effects of grain size, thermal segregation, as well as injected interstitials (introduced as Fe self-ions). The results indicate that the Cr enrichment at grain boundaries may be caused by combined effects of grain size, self-ion injection and preferential Cr diffusion via the interstitial mechanism. In conclusion, the findings also suggest a possible difference in RIS between ion and neutron irradiations.
36 MATERIALS SCIENCE↗
Ion implantation damage effects in silicon
Ion implantation lattice damage effects in crystalline silicon with allowance for optical reflectivity, considering annealing temperature and amorphous layer formation
Eberle, D. E.↗
Electronic and Vibrational Spectra of InP Quantum Dots Formed by Sequential Ion Implantation
We have performed sequential ion implantation of indium and phosphorus into silica combined with controlled thermal annealing to fabricate InP quantum dots in a dielectric host. Electronic and vibrational spectra were measured for the as-implanted and annealed samples. The annealed samples show a peak in the infrared spectra near 320/cm which is attributed to a surface phonon mode and is in good agreement with the value calculated from Frolich's theory of surface phonon polaritons. The electronic spectra show the development of a band near 390 nm that is attributed to quantum confined InP.
Hall, C.↗
Evaluation of the ion implantation process for production of solar cells from silicon sheet materials
The objective of this program is the investigation and evaluation of the capabilities of the ion implantation process for the production of photovoltaic cells from a variety of present-day, state-of-the-art, low-cost silicon sheet materials. Task 1 of the program concerns application of ion implantation and furnace annealing to fabrication of cells made from dendritic web silicon. Task 2 comprises the application of ion implantation and pulsed electron beam annealing (PEBA) to cells made from SEMIX, SILSO, heat-exchanger-method (HEM), edge-defined film-fed growth (EFG) and Czochralski (CZ) silicon. The goals of Task 1 comprise an investigation of implantation and anneal processes applied to dendritic web. A further goal is the evaluation of surface passivation and back surface reflector formation. In this way, processes yielding the very highest efficiency can be evaluated. Task 2 seeks to evaluate the use of PEBA for various sheet materials. A comparison of PEBA to thermal annealing will be made for a variety of ion implantation processes.
Spitzer, M. B.↗
Tuning Chiral Anomaly Signature in a Dirac Semimetal via Fast-Ion Implantation
Cd 3 As 2 is a Dirac semimetal that hosts a chiral anomaly, functioning as a platform to realize energy applications. We use fast-ion implantation to enhance the negative longitudinal magnetoresistance (NLMR)─signature of a chiral anomaly─in Nb-doped Cd 3 As 2 thin films. High-energy ion implantation is used to investigate semiconductors and nuclear materials but is rarely employed to study topological materials. We use electrical transport and transmission electron microscopy to characterize the NLMR and crystallinity of Nb-doped Cd 3 As 2 . We find surface-doped thin films display a maximum NLMR around B = 7 T and bulk-doped thin films display a maximum over B = 9 T─all while maintaining crystallinity. This is more than a 100% relative enhancement of the maximum NLMR compared to pristine Cd 3 As 2 . As a result, our work demonstrates the potential of high-energy ion implantation as a practical route to explore chiralitronic properties in topological semimetals.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Development of ion implanted gallium arsenide transistors
Techniques were developed for creating bipolar microwave transistors in GaAs by ion implantation doping. The electrical properties of doped layers produced by the implantation of the light ions Be, Mg, and S were studied. Be, Mg, and S are suitable for forming the relatively deep base-collector junction at low ion energies. The electrical characteristics of ion-implanted diodes of both the mesa and planar types were determined. Some n-p-n planar transistor structures were fabricated by implantation of Mg to form the base regions and Si to form the emitters. These devices were found to have reasonably good base-collector and emitter-base junctions, but the current gain beta was small. The low was attributable to radiative recombination in the base region, which was extremely wide.
Hunsperger, R.↗
Ion Implantation in Narrow-Gap Cd{sub x}Hg{sub 1–x}Te Solid Solutions
The results of experimental studies of processes of the radiation defect formation under ion implantation of narrow-gap Cd{sub x}Hg{sub 1-x}Te solid solutions (MCT) are presented. The processes of formation of structural damages of the crystal and their effect on the electrophysical properties of ion-implanted bulk crystals and ptype heteroepitaxial structures grown by liquid-phase and molecular-beam epitaxy are considered. The results on the spatial distribution of implanted boron atoms and radiation donor centers in these materials are presented as a function of the mass, dose, and energy of ions being implanted and the implantation temperature. The processes and models of the formation of n{sup +}–n{sup -}–p-structures during boron ion implantation in p-type MCT and their experimental proof are considered.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Combining femtosecond laser annealing and shallow ion implantation for local color center creation in diamond
A common technique for color center creation in wideband gap semiconductors employs ion implantation and a subsequent thermal annealing. In general, this annealing process is conducted in a vacuum oven. Here, we exploit the annealing based on femtosecond laser pulses. For that purpose, we implant fluorine ions at 54 keV and chlorine ions at 74 keV in diamond and perform micrometer precise annealing using focused femtosecond laser pulses at 800 ± (30) nm with different pulse numbers and repetition rates. In this way, we were able to create shallow spots with color centers of varying brightness.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
High Mobility SiGe/Si Transistor Structures on Sapphire Substrates Using Ion Implantation
High mobility n-type SiGe/Si transistor structures have been fabricated on sapphire substrates by ion implanting phosphorus ions into strained 100 Angstrom thick silicon channels for the first time. The strained Si channels were sandwiched between Si(sub 0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer layers. After the molecular beam epitaxy (MBE) film growth process was completed, ion thick silicon channels implantation and post-annealing were used to introduce donors. The phosphorous ions were preferentially located in the Si channel at a peak concentration of approximately 1x10(exp 18)/cu cm. Room temperature electron mobilities exceeding 750 sq cm/V-sec at carrier densities of 1x10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that determines mobility, with the highest mobility observed for electron densities in the 1 - 2x10(exp 12)/sq cm range.
Alterovitz, S. A.↗
Ion implantation reduces radiation sensitivity of metal oxide silicon /MOS/ devices
Implanting nitrogen ions improves hardening of silicon oxides 30 percent to 60 percent against ionizing radiation effects. Process reduces sensitivity, but retains stability normally shown by interfaces between silicon and thermally grown oxides.
Source record↗
Ion probe analysis of artificially implanted ions in terrestrial samples and surface enhanced ions in lunar sample 76215,77
Explore the source record for details and available documents.
Zinner, E.↗
A fitting algorithm for optimizing ion implantation energies and fluences
In this work we describe a method to automatically generate an ion implantation recipe, a set of energies and fluences, to produce a desired defect density profile in a solid using the fewest required energies. We simulate defect density profiles for a range of ion energies, fit them with an appropriate function, and interpolate to yield defect density profiles at arbitrary ion energies. Given Ν energies, we then optimize a set of Ν energy-fluence pairs to match a given target defect density profile. Finally, we find the minimum Ν such that the error between the target defect density profile and the defect density profile generated by the Ν energy-fluence pairs is less than a given threshold. Inspired by quantum sensing applications with nitrogen-vacancy centers in diamond, we apply our technique to calculate optimal ion implantation recipes to create uniform-density 1 μm surface layers of 15 N or vacancies (using 4 He).
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Stress engineering for crack and dendrite prevention in solid electrolytes via ion implantation
Solid-state batteries represent a promising technology that offers safer and more densely packed energy storage. A primary cause of failure in solid-state cells is the penetration of metal dendrites through the solid electrolyte. Here, we report that fluorine-ion implantation can enhance the mechanical resistance of solid electrolyte Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 to dendrite propagation by inducing residual compressive stress in the subsurface of the electrolyte. Ion implantation modifies subsurface residual stress and also alters the electrolyte’s surface, resulting in multifunctional enhancement. The combined chemical and mechanical effects of ion implantation enable reversible lithium metal stripping and plating at elevated current densities while enhancing air stability and mitigating the formation of a harmful carbonate layer at the surface. This study provides new insights into a scalable dendrite-suppression strategy for designing solid-state batteries suitable for cycling at room temperature and low stack pressures.
25 ENERGY STORAGE↗
Thermal annealing behavior of hydrogen and surface topography of H 2 + ion implanted tungsten
Tungsten (W) has been proposed as a plasma-facing material (PFM) in fusion reactors due to its outstanding properties. Degradation of the material properties is expected to occur as a result of hydrogen (H) isotope permeation and trapping in W. In this study, two polycrystalline W plates were implanted with 80 keV H 2 + ions to a fluence of 2E21 H+/m2 at room temperature (RT). Time-of-flight secondary ion mass spectrometry (ToF-SIMS), focused ion beam (FIB) and scanning electron microscopy (SEM) were used for sample characterization. The SIMS data shows that H atoms are distributed well beyond the ion projected range. Isochronal annealing appears to suggest two H release stages that might be associated with the reported activation energies. H release at RT was observed between days 10 and 70 following ion implantation, and the level was maintained over the next 60 days. In addition, FIB/SEM results exhibit H2 blister formation near the surface of the as-implanted W. The blister distribution remains unchanged after thermal annealing up to 600 °C.
H diffusion and release↗
Ion implantation of magnesium guests into type II silicon clathrate films: an alternate approach to doping a cage-like silicon allotrope
Type II silicon clathrates, with their unique cage-like structure, offer exciting potential for applications in thermoelectrics, photovoltaics, and quantum materials due to their tunable electronic and thermal properties. This study investigates the use of ion implantation to introduce targeted guest atoms, which act as dopants, into type II Si clathrate films. The focus is on Mg as a test case for implantation, a dopant previously unreported in type II Si clathrates. The effects of ion implantation on the metastable Si clathrate structure were examined through systematic investigation of implant parameters. Time-of-flight secondary ion mass spectrometry depth profiling confirmed the successful implantation of Mg, while X-ray diffraction and confocal Raman spectroscopy demonstrated minimal structural damage at lower fluences, with the clathrate framework retaining its integrity without converting to other phases. At the higher end of the fluence range implantation caused localized transitions from clathrate to amorphous silicon. Implant activation using rapid thermal annealing was examined with the clathrate structure stable up to 500 °C and being converted to diamond silicon above this temperature. Post-implantation and activation structural characterization showed evidence of damage reversal. Electron paramagnetic resonance studies provided indirect evidence of dopant incorporation. These findings establish a foundation for introducing alternative guests/dopants into the Si clathrate cages through ion implantation, advancing their tunability for next-generation quantum and optoelectronic devices.
36 MATERIALS SCIENCE↗
Synthesis of magnesiowüstite nanocrystallites embedded in an amorphous silicate matrix via low energy multiple ion implantations
The synthesis process is presented for experimentally simulating modifications in cosmic dust grains using sequential ion implantations or irradiations followed by thermal annealing. Cosmic silicate dust analogues were prepared via implantation of 20–80 keV Fe - , Mg - , and O - ions into commercially available p-type silicon (100)wafers. The as-implanted analogues are amorphous with a Mg/(Fe+Mg) ratio of 0.5 tailored to match theoretical abundances in circumstellar dusts. Before the ion implantations were performed, Monte-Carlo-based ion-solid interaction codes were used to model the dynamic redistribution of the implanted atoms in the silicon substrate. 600 keV helium ion irradiation was performed on one of the samples before thermal annealing. Two samples were thermally annealed at a temperature appropriate for an M-class stellar wind, 1000 K, for 8.3 h in a vacuum chamber with a pressure of 1 x 10 -7 torr. The elemental depth profiles were extracted utilizing Rutherford Backscattering Spectrometry (RBS) in the samples before and after thermal annealing. X-ray diffraction (XRD)analysis was employed for the identification of various phases in crystalline minerals in the annealed analogues. Transmission electron microscopy (TEM) analysis was utilized to identify specific crystal structures. RBS analysis shows redistribution of the implanted Fe, Mg, and O after thermal annealing due to incorporation into the crystal structures for each sample type. XRD patterns along with TEM analysis showed nanocrystalline Mg and Fe oxides with possible incorporation of additional silicate minerals.
79 ASTRONOMY AND ASTROPHYSICS↗
A study of the factors which control the efficiency of ion-implanted silicon solar cells
The objective of this work was to determine experimentally the ion-implantation parameters and furnace annealing conditions required to produce high-efficiency solar cells. A comprehensive experimental study was conducted in which the optimum ion-implantation parameters were found by a systematic variation of the implant parameters followed by detailed studies of solar-cell devices. Two furnace heat-treatment techniques were found which effectively anneal the implanted layers and at the same time preserve or improve the diffusion length in the bulk silicon. Detailed characteristics of both the junction and bulk properties of solar cells fabricated over the spectrum of implant parameters are discussed. Optimized implant parameters and annealing conditions were found which allow for the fabrication of 14-15-percent (AM1) efficient solar cells.
Douglas, E. C.↗