Low-energy heavy-ion irradiations of copper and molybdenum at low temperatures

1991 ◽  
Vol 435 (1893) ◽  
pp. 85-108 ◽  
Keyword(s):  
Room Temperature ◽  
Experimental System ◽  
Heavy Ion ◽  
Low Energy ◽  
Dislocation Loops ◽  
Retention Efficiency ◽  
Near Surface ◽  
Warm Up ◽  
Surface Vacancy ◽  
Depth Distributions

A specially designed and characterized oil-free cryogenic UHV experimental system has been used to irradiate pre-thinned orientated copper and molybdenum single crystals at 4.2 and 78 K with very high doses (5 x 10 12 to 5 x 10 15 ions cm -2 ) of low-energy (0.2-20 keV) self-ions and xenon ions. Populations of dislocation loops were produced, after subsequent warm-up to room temperature, within a few hundred ångströms of the irradiated surface. The loop depth distributions were measured using stereo transmission electron microscope (TEM) techniques and correlated with possible displacement damage production and retention mechanisms, including replacement collision sequences (RCSS), incident ion channelling and near-surface loop losses. In copper, both near-surface vacancy-loop populations at depths up to about 100Å and deeper interstitial loops up to about 400Å in depth could be produced. In molybdenum only interstitial loops were visible, at depths up to about 250Å. The depth distributions depended critically on the incident ion mass, ion energy and the specimen surface orientation used. In all the copper and molybdenum irradiations at doses greater than 10 13 ions cm -2 only a very small fraction (not more than 2%) of the point defects theoretically created during the irradiations at 4.2 K were retained in visible loops after warm-up to room temperature. The results are consistent with displacement cascades, initiated by incident ions, injecting some interstitials along RCSS directed away from the irradiated surface, which may subsequently aggregate into interstitial loops. It is concluded that the loop depth distributions are determined more by the fraction of incident ions channelled at the irradiated surface than on RCS orientation effects relative to the surface. The low point defect retention efficiency in the present study is consistent with RCS ranges of only a few tens of ångströms at most. However, the lattice is highly damaged during the irradiation, possibly leading to enhanced RCS defocusing. Irradiation at 78K provides results consistent with interstitial mobility at this temperature.

THE COLLIDING PARTICLES MASS RATIO INFLUENCE ON PECULIARITIES OF LOW-ENERGY ION NEAR-SURFACE IMPLANTATION AT CHANNELING CONDITIONS

2018 ◽  
Vol 20 (4) ◽  
pp. 265-274
Author(s):  
F.F. Umarov ◽  
A.M. Rasulov ◽  
A.A. Dzhurakhalov
Keyword(s):  
Energy Loss ◽  
Normal Incidence ◽  
Binary Collision ◽  
Low Energy ◽  
Main Peak ◽  
Mass Ratio ◽  
Near Surface ◽  
Collision Approximation ◽  
Thin Crystal ◽  
Depth Distributions

In the present work the peculiarities of ion implantation and colliding particles mass ratio influence on the ranges, energy loss and profiles of distribution for 1−5 keV P+ ions channelling in Si(110) and SiC(110) at normal incidence, and 1 keV Be+ and Se+ ions in GaAs(100), as well as 5 keV Ar+ and Kr+ on Cu(001) surface at glancing incidence are carried out by computer simulation in binary collision approximation. It is shown that for paraxial part of a beam the main contribution to the total energy loss comes from inelastic ones. It has been established that the energy loss of ions transmitted through thin crystal and depth profile distributions depend on width of the channel and mass ratio of colliding atoms. It was shown that at grazing surface channeling conditions the main peak of the implanted depth distributions is considerably shallow, the range for Se+ ions is shallower and the half-width of profile for these ions is narrow than that for Be+ ions. The results allow one to select the optimum for implanted depth distributions with demanded shape at narrow near-surface area of crystals obtaining.

scholarly journals Effects of the Surface on Displacement Cascades Produced by Heavy-Ion Irradiation of Ni3Al and Cu3Au

1996 ◽  
Vol 439 ◽  
Author(s):  
S. Müller ◽  
M. L. Jenkins ◽  
C. Abromeit ◽  
H. Wollenberger
Keyword(s):  
Ion Irradiation ◽  
Incident Angle ◽  
Ion Beam ◽  
Heavy Ion ◽  
Small Population ◽  
Dislocation Loops ◽  
Near Surface ◽  
Ion Energy ◽  
Heavy Ion Irradiation ◽  
Transmission Electron

AbstractStereo transmission electron microscopy has been used to characterise the distribution in depth of disordered zones and associated dislocation loops in the ordered alloys Ni3Al and Cu3Au after heavy ion irradiation, most extensively for Ni3Al irradiated with 50 keV Ta+ ions at a temperature of 573 K. The Cu3Au specimen was irradiated with 50 keV Ni+ ions at an incident angle of 45° at a temperature of 373 K. In Ni3Al the defect yield, i.e. the probability for a disordered zone to contain a loop was found to be strongly dependent on the depth of the zone in the foil, varying from about 0.7 for near-surface zones to about 0.2 in the bulk. The sizes and shapes of disordered zones were only weakly dependent on depth, except for a small population of zones very near the surface which were strongly elongated parallel to the incident ion beam. In Cu3Au the surface had a smaller but still significant effect on the defect yield. The dependence of the tranverse disordered zone diameter d on ion energy E for Ta+ irradiation of NiA was found to follow a relationship d = k1, E1/α with k, = 2.4 ± 0.4 and α = 3.3 ± 0.4. A similar relationship with the same value of α is valid for a wide variety of incident ion/target combinations found in the literature.

Microstructural Developments During Implantation of Metals

1983 ◽  
Vol 27 ◽  
Author(s):  
D. I. Potter ◽  
M. Ahmed ◽  
S. Lamond
Keyword(s):  
Chemical Composition ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Auger Spectroscopy ◽  
Phase Region ◽  
Dislocation Loops ◽  
Two Phase ◽  
Model Calculations ◽  
Near Surface ◽  
Composition Profiles

ABSTRACTThe chemical and microstructural changes caused by the direct implantation of solutes into metals are examined. The particular case involving Al+-ion implantation into nickel is treated in detail. Chemical composition profiles measured using Auger spectroscopy and Rutherford backscattering, and average near-surface chemical composition measured using an analytical electron microscope, are compared with model calculations. The microstructures that develop during implantation are investigated using transmission electron microscopy. For low fluences implanted near room temperature, these microstructures contain dislocations and dislocation loops. Dislocation loops, dislocations, and voids result from implantations at temperatures near 500°C. Higher fluences at these elevated temperatures produce precipitates when the composition of implanted solute lies in a two-phase region of the phase diagram. Implanted concentrations corresponding to intermetallic compounds produce continuous layers of these compounds. Room temperature, as compared to elevated temperature, implantation may produce the same phases at the appropriate concentrations, e.g. β'-NiAl, or different phases, depending on the relative stability of the phases involved.

Influence of the Temperature of Implantation on the Morphology of Defects in MeV Implanted GaAs.

1989 ◽  
Vol 147 ◽  
Author(s):  
G. Braunstein ◽  
Samuel Chen ◽  
S.-Tong Lee ◽  
G. Rajeswaran.
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Point Defects ◽  
Room Temperature ◽  
Surface Region ◽  
Amorphous Region ◽  
Liquid Nitrogen Temperature ◽  
Dislocation Loops ◽  
Near Surface ◽  
Epitaxial Regrowth

AbstractWe have studied the influence of the temperature of implantation on the morphology of the defects created during 1-MeV implantation of Si into GaAs, using RBS-channeling and TEM. The annealing behavior of the disorder has also been investigated.Implantation at liquid-nitrogen temperature results in the amorphization of the implanted sample for doses of 2×1014 cm−2 and larger. Subsequent rapid thermal annealing at 900°C for 10 seconds leads to partial epitaxial regrowth of the amorphous layer. Depending on the implantation dose, the regrowth can proceed from both the front and back ends of the amorphous region or only from the deep end of the implanted zone. Nucleation and growth of a polycrystalline phase occurs concurrently, limiting the extent of the epitaxial regrowth. After implantation at room temperature and above, two distinct types of residual defects are observed or inferred: point defect complexes and dislocation loops. Most of the point defects disappear after rapid thermal annealing at temperatures ≥ 700°C. The effect of annealing on the dislocation loops depends on the distance from the surface of the sample. Those in the near surface region disappear upon rapid thermal annealing at 700°C, whereas the loops located deeper in the sample grow in size and begin to anneal out only at temperatures in excess of 900°C. Implantation at temperatures of 200 - 300°C results in a large reduction in the number of residual point defects. Subsequent annealing at 900°C leads to a nearly defect-free surface region and, underneath that, a buried band of partial dislocation loops similar to those observed in the samples implanted at room temperature and subsequently annealed.

Heterogeneous Precipitation at Dislocations

1969 ◽  
Vol 27 ◽  
pp. 70-71
Author(s):  
A. K. Eikum
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Dislocation Loops ◽  
Silver Alloys ◽  
Heterogeneous Precipitation ◽  
Precipitation Phenomena ◽  
Aluminum Base ◽  
Silver Atoms

Precipitation phenomena in concentrated aluminum-base silver alloys have been studied with a variety of techniques including electron microscopy. The purpose of the present work was to investigate the dislocation reactions that occur as silver atoms precipitate (or segregate) under a relatively low supersaturation. Specimens (0.1 mm thick) of Al-1 at. % Ag were quenched from ~500°C into an oil bath at room temperature and aged 30 min. at 265°C. The initial configurations available as sites for heterogeneous precipitation will therefore include perfect prismatic dislocation loops, Frank sessile loops and random segments of grown-in dislocations.

scholarly journals Low-energy room-temperature optical switching in mixed-dimensionality nanoscale perovskite heterojunctions

2021 ◽  
Vol 7 (18) ◽  
pp. eabf1959
Author(s):  
Ji Hao ◽  
Young-Hoon Kim ◽  
Severin N. Habisreutinger ◽  
Steven P. Harvey ◽  
Elisa M. Miller ◽  
...  
Keyword(s):  
Optical Switching ◽  
Room Temperature ◽  
Optical Memory ◽  
Low Energy ◽  
Optical Measurements ◽  
Ion Migration ◽  
Metal Halide Perovskite ◽  
Conductance Changes ◽  
Optical Domain ◽  
Walled Carbon Nanotubes

Long-lived photon-stimulated conductance changes in solid-state materials can enable optical memory and brain-inspired neuromorphic information processing. It remains challenging to realize optical switching with low-energy consumption, and new mechanisms and design principles giving rise to persistent photoconductivity (PPC) can help overcome an important technological hurdle. Here, we demonstrate versatile heterojunctions between metal-halide perovskite nanocrystals and semiconducting single-walled carbon nanotubes that enable room-temperature, long-lived (thousands of seconds), writable, and erasable PPC. Optical switching and basic neuromorphic functions can be stimulated at low operating voltages with femto- to pico-joule energies per spiking event, and detailed analysis demonstrates that PPC in this nanoscale interface arises from field-assisted control of ion migration within the nanocrystal array. Contactless optical measurements also suggest these systems as potential candidates for photonic synapses that are stimulated and read in the optical domain. The tunability of PPC shown here holds promise for neuromorphic computing and other technologies that use optical memory.

Investigation of the Hydrogen Transport Processes in Crystalline Silicon of n-Type Conductivity

2007 ◽  
Vol 131-133 ◽  
pp. 425-430 ◽  
Author(s):  
Anis M. Saad ◽  
Oleg Velichko ◽  
Yu P. Shaman ◽  
Adam Barcz ◽  
Andrzej Misiuk ◽  
...  
Keyword(s):  
Hydrogen Concentration ◽  
Room Temperature ◽  
Crystalline Silicon ◽  
Transport Processes ◽  
Concentration Profiles ◽  
Hydrogen Transport ◽  
Hydrogen Atoms ◽  
Near Surface ◽  
Type Conductivity ◽  
Hydrogen Molecules

The silicon substrates were hydrogenated at approximately room temperature and hydrogen concentration profiles vs. depth have been measured by SIMS. Czochralski grown (CZ) wafers, both n- and p-type conductivity, were used in the experiments under consideration. For analysis of hydrogen transport processes and quasichemical reactions the model of hydrogen atoms diffusion and quasichemical reactions is proposed and the set of equations is obtained. The developed model takes into account the formation of bound hydrogen in the near surface region, hydrogen transport as a result of diffusion of hydrogen molecules 2 H , diffusion of metastable complexes * 2 H and diffusion of nonequilibrium hydrogen atoms. Interaction of 2 H with oxygen atoms and formation of immobile complexes “oxygen atom - hydrogen molecule” (O - H2 ) is also taken into account to explain the hydrogen concentration profiles in the substrates of n-type conductivity. The computer simulation based on the proposed equations has shown a good agreement of the calculated hydrogen profiles with the experimental data and has allowed receiving a value of the hydrogen molecules diffusivity at room temperature.

ION CHANNELING AND PIXE STUDIES OF S IMPLANTATION IN GaAs

1992 ◽  
Vol 02 (02) ◽  
pp. 151-159
Author(s):  
LIU SHIJIE ◽  
WANG JIANG ◽  
HU ZAOHUEI ◽  
XIA ZHONGHUONG ◽  
GAO ZHIGIANG ◽  
...  
Keyword(s):  
Room Temperature ◽  
Dislocation Loops ◽  
Good Recovery ◽  
Electrical Measurements ◽  
X Ray ◽  
Defect Complexes ◽  
Ion Channeling ◽  
Transmission Electron ◽  
Activation Efficiency ◽  
Very High

GaAs (100) crystals were implanted with 100 keV S+ to a dose of 3×1015 cm−2 in a nonchanneling direction at room temperature, and treated with rapid thermal annealing (RTA). He+ Rutherford backscattering and particle-induced X-ray emission in channeling mode in combination with transmission electron microscopy (TEM) were used to study the damage and the lattice location of S atoms. It is revealed that the RTA at 950 °C for 10 sec has resulted in a very good recovery of crystallinity with a few residual defects in the form of dislocation loops, and a very high substitutionality (~90%). The activation efficiency and the Hall mobility of the implanted samples are found to be low after the electrical measurements. Based on these results an extended dopant diffusion effect for the residual defects and a correlation between the electrical properties and defect complexes are suggested.

Off-Line Direct Deposition Gas Chromatography/Surface-Enhanced Raman Scattering and the Ramifications for On-Line Measurements

2005 ◽  
Vol 59 (11) ◽  
pp. 1305-1309 ◽  
Author(s):  
David A. Heaps ◽  
Peter R. Griffiths
Keyword(s):  
Gas Chromatography ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Room Temperature ◽  
Warm Up ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
On Line ◽  
Enhanced Raman Scattering ◽  
Moving Liquid

Surface-enhanced Raman spectra (SERS) of molecules separated by gas chromatography (GC) were measured off-line by condensing the analyte on a moving, liquid-nitrogen-cooled ZnSe window on which a 5 nm layer of silver had been formed by physical vapor deposition. After the components that eluted from the chromatograph had been deposited, the substrate was allowed to warm up to room temperature and transferred to the focus of a Raman microspectrometer where the spectrum of each component was measured. Band intensities in the spectrum of 3 ng of caffeine prepared in this way were approximately the same as in the spectrum of bulk caffeine. By making some logical assumptions, it was shown that identifiable GC/SERS spectra of 30 pg of many molecules could be measured over a 300 cm−1 region in real-time and that if an optimized substrate were used the minimum identifiable quantity could be reduced to 1 pg or less.

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