Defect Formation During Zn Diffusion into GaAs

1989 ◽  
Vol 163 ◽  
Author(s):  
Martina Luysberg ◽  
W. Jäger ◽  
K. Urban ◽  
M. Perret ◽  
N.A. Stolwijk ◽  
...  
Keyword(s):  
Defect Formation ◽  
Analytical Electron Microscopy ◽  
Surface Region ◽  
Dislocation Loops ◽  
Diffusion Front ◽  
Near Surface ◽  
Zn Diffusion ◽  
Zn Concentration ◽  
Analytical Electron ◽  
Type Dislocation

AbstractThe microstructure induced by the Zn diffusion at 1170 K into doped and undoped semi-insulating GaAs single crystals was characterized for various diffusion times t < 1740 min by analytical electron microscopy. The results were compared with Zn concentration profiles obtained by spreading resistance measurements (SRM) on the same samples. At the diffusion front the formation of prismatic interstitial dislocation loops, dislocation networks, and of cavities partly filled with Ga was observed. Closer to the surface facetted voids and, for the undoped samples, vacancy-type dislocation loops formed. The near surface region of highest Zn-concentration showed a high density of Zn-rich precipitates. A model is presented which accounts .for these observations. It is based on fast interstitial Zn diffusion and the kick-out mechanism for interstitial-substituional exchange.

Analytical electron microscopy of TiB2 implanted with 1 MeV nickel

1983 ◽  
Vol 41 ◽  
pp. 66-67
Author(s):  
P. S. Sklad ◽  
P. Anqelini ◽  
M. B. Lewis ◽  
J. T. Houston ◽  
C. J. McHargue
Keyword(s):  
Concentration Level ◽  
Analytical Electron Microscopy ◽  
Surface Region ◽  
Near Surface ◽  
Energetic Ions ◽  
Nickel Ions ◽  
X Ray ◽  
Ambient Temperatures ◽  
Analytical Electron ◽  
Argon Ion

Recently a series of studies has been undertaken to determine the effect of ion implantation on the properties of structural ceramics. In the technique energetic ions impinge on the surface of the material displacing atoms, creating various types of point defects, and finally come to rest in the near-surface region. Because of the nature of these processes it is possible to introduce an element into the substrate to a concentration level much higher than normal equilibrium would allow. The present study is concerned with the microstructure produced by implanting TiB2 with 1 MeV nickel ions.Polycrystalline samples of TiB2 were implanted at ambient temperatures with 1 MeV Ni+ ions to a fluence of 1 × 1017 ions/cm2. The implanted samples were cut into pieces approximately 1 mm × 2 mm × 5 mm and pairs were glued together with the implanted surfaces facing each other. Slices ∼250 μm thick were then cut, mechanically polished to ∼75 μm, mounted on copper washers, and argon ion milled. This procedure allowed examination of the implanted layer in cross section. The TEM specimens were then examined in a JEM 120CX equipped with a Kevex 5100 x-ray energy dispersive spectroscopy (EDS) system interfaced to a PDP-11/34 computer and peripherals.

Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

Analytical Electron Microscopy of Ion-Implanted Metals

1985 ◽  
Vol 43 ◽  
pp. 282-285
Author(s):  
D.I. Potter ◽  
M. Ahmed ◽  
K. Ruffing
Keyword(s):  
Electron Microscopy ◽  
Ion Implantation ◽  
Friction And Wear ◽  
Analytical Electron Microscopy ◽  
Chemical Compositions ◽  
Surface Chemical ◽  
Near Surface ◽  
The Past ◽  
Analytical Electron ◽  
Property Changes

Ion implantation, used extensively for the past decade in fabricating semiconductor devices, now provides a unique means for altering the near-surface chemical compositions and microstructures of metals. These alterations often significantly improve physical properties that depend on the surface of the material; for example, catalysis, corrosion, oxidation, hardness, friction and wear. Frequently the mechanisms causing these beneficial alterations and property changes remain obscure and much of the current research in the area of ion implantation metallurgy is aimed at identifying such mechanisms. Investigators thus confront two immediate questions: To what extent is the chemical composition changed by implantation? What is the resulting microstructure? These two questions can be investigated very fruitfully with analytical electron microscopy (AEM), as described below.

Analytical electron microscopy of SiC implanted with Cr ions

1984 ◽  
Vol 42 ◽  
pp. 416-417
Author(s):  
P. S. Sklad ◽  
P. Angelini ◽  
C. J. McHargue ◽  
J. M. Williams
Keyword(s):  
Electron Microscopy ◽  
Depth Distribution ◽  
Analytical Electron Microscopy ◽  
Surface Microstructure ◽  
Polycrystalline Specimen ◽  
Near Surface ◽  
Ambient Temperatures ◽  
Chromium Ions ◽  
Analytical Electron ◽  
Post Implantation

Silicon carbide is an attractive structural material for high temperature applications that require chemical stability in aggressive environments and wear resistance. In order to investigate ion implantation as a means of improving surface properties, specimens of SiC were implanted with chromium ions. The present work is concerned with characterizing the near-surface microstructure produced by implantation and monitoring changes which occur during post-implantation annealing.A polycrystalline specimen of α SiC, pressureless sintered with boron additions by the Carburundum Co., was implanted with chromium ions at ambient temperatures. In order to obtain a broad fairly uniform depth distribution a multiple-energy implant schedule was employed: 4.03 x 1015 Cr ions/cm2 were implanted at 95 keV, 7.26 x 1015 Cr ions/cm2 were implanted at 190 kev, and 10 x 1015 Cr ions/cm2 were implanted at 280 keV.

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.

Defects Near the Y2BaCuO5/YBa2Cu3O7−x Interface and their Effect on Flux-Pinning in Melt-Processed and Quench-Melt-Growth Processed YBa2Cu3O7−x

1992 ◽  
Vol 275 ◽  
Author(s):  
Z. L. Wang ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
T. Armstrong
Keyword(s):  
Applied Field ◽  
Flux Pinning ◽  
Volume Fraction ◽  
Analytical Electron Microscopy ◽  
Stacking Faults ◽  
Detailed Examination ◽  
Dislocation Loops ◽  
Fault Density ◽  
Analytical Electron ◽  
X Interface

ABSTRACTA detailed examination of the Y2BaCuO5 (211)/ YBa2Cu3O7−x (123) interface in several melt-processed 123 samples prepared using different methods was undertaken using analytical electron microscopy. It is found that there exists a significant increase in the a-b planar stacking fault density in 123, near the 211/123 interface. When viewed along [001], these faults appear as disks with diameter from a few to 30 nm and are bounded by dislocation loops. Most stacking faults are confined to the (001) basal plane. The size and density of defects around the 211 particles suggest that these defects could act as effective flux-pinning sites and may explain the observations of increased Jc with increasing volume fraction of 211 and a maximum in Jc when the applied field parallel to the c-axis.

Device Parametric Shift Mechanism Caused by Boron Halo Redistribution Resulting from Dose Rate Dependence of SDE Implant

2005 ◽  
Vol 864 ◽  
Author(s):  
Ukyo Jeong ◽  
Jinning Liu ◽  
Baonian Guo ◽  
Kyuha Shim ◽  
Sandeep Mehta
Keyword(s):  
Surface Region ◽  
Amorphous Region ◽  
Amorphous Layer ◽  
High Dose ◽  
Extended Defects ◽  
Dislocation Loops ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
Dose Rates ◽  
Pile Up

AbstractChange in dopant diffusion was observed for Arsenic source drain extension (SDE) implants when they were performed at various dose rates. The high dose SDE implant amorphizes the surface of the silicon substrate and the thickness of the amorphous layer is strongly influenced by the rate of dopant bombardment. It is well known that the ion implantation process introduces excess interstitials. While the amorphous region is completely re-grown into single crystal during subsequent anneal without leaving behind extended defects, interstitials that are injected beyond the amorphous layer lead to formation of {311} defects or dislocation loops in the end of range region. During thermal processing, these extended defects dissolve, release interstitials, which in turn lead to transient enhanced diffusion of underlying Boron halo dopant. Dopant depth profiles measured by SIMS revealed different amount of Boron pile-up in the near surface region, corresponding to different SDE implant dose rates. In CMOS devices, this surface pile-up would correlate with a Boron pile-up in the channel region that would lead to a shift in transistor characteristics. Through this investigation, we were able to explain the mechanism causing device characteristics shift resulted from SDE implant with the same dose and energy but different dose rates.

Analytical Electron Microscopy of α-Al2O3 implanted with iron

1987 ◽  
Vol 45 ◽  
pp. 146-147
Author(s):  
P. S. Sklad
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Analytical Electron Microscopy ◽  
Microstructural Development ◽  
Near Surface ◽  
Analytical Electron ◽  
Α Al2o3 ◽  
Fe Ions ◽  
Post Implantation ◽  
Flowing Oxygen

Ion implantation has become an accepted method for achieving a wide variation in the near surface microstructure and properties of many materials. A number of recent studies have concentrated on modifying the properties of Al2O3. However, the effectiveness of such surface modification is strongly dependent on the microstructural development which takes place in the implanted region during post-implantation annealing. Analytical electron microscopy (AEM) techniques are unique in that they allow direct observation of changes in microstructure and composition which are produced during such anneals.Single crystals of α-Al2O3 in the basal orientation were implanted with 160 keV Fe ions to a dose of 4 x 1016 or 1 x 1017 ions/cm2 with a dose rate of ∼2 amps/cm2. The implantations were carried out at room temperature. A number of specimens were subsequently annealed for 1 h at temperatures in the range 973 K to 1773 K in flowing oxygen.

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