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Ion-beam-induced amorphization and recrystallization in silicon
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10.1063/1.1808484
/content/aip/journal/jap/96/11/10.1063/1.1808484
http://aip.metastore.ingenta.com/content/aip/journal/jap/96/11/10.1063/1.1808484

Figures

Image of FIG. 1.
FIG. 1.

Sheet resistance vs electrical junction depth in a comparison of promising junction approaches for C-MOS and below (after Ref. 32).

Image of FIG. 2.
FIG. 2.

On the left we show a thin slab ( thick) of . Each atom is located in the center of a tetrahedron and bounded with the four atoms of their vertices. Atoms form the six-membered rings typical of the diamond structure. On the right we represent a slab of of the same thickness. Even tough mean coordination is still four, long range order is lost. Five- and seven-membered atom rings are clearly visible.

Image of FIG. 3.
FIG. 3.

Local rearrangement of bonds used to generate the WWW model of : (a) configuration of bonds in the perfect diamond lattice and (b) relaxed configuration of atoms after switching the bonds (from Ref. 46).

Image of FIG. 4.
FIG. 4.

Atomic structures of (a) the floating bond, (b) the dangling bond, and (c) the highly distorted fourfold coordinated atom. These structures have been obtained using first-principle techniques (from Ref. 50).

Image of FIG. 5.
FIG. 5.

Phase diagram for , where Gibbs free-energy differences for the crystal, liquid, and amorphous phases are represented as a function of temperature. From the line intersection points it is possible to extract the melting temperatures and (after Ref. 73).

Image of FIG. 6.
FIG. 6.

Radial distribution functions for (a) at room temperature, (b) at room temperature, and (c) liquid at the melting point. All of them were obtained from MD simulations.

Image of FIG. 7.
FIG. 7.

Morphology of the damage created by the implantation of (a) a ion and (b) a As ion, as obtained by MD techniques. The damage energy is the same for both ions . Atoms displayed have a potential energy higher than the reference crystal. While B creates mainly isolated Frenkel pairs and small clusters, As produces more extended disordered zones (after Ref. 125).

Image of FIG. 8.
FIG. 8.

(a) Experimentally measured recrystallization behavior at of a single amorphous zone created by ion irradiation (from Ref. 140). (b) Number of atoms in an amorphous pocket generated by a As implant as a function of time for several temperatures, as obtained using MD techniques (from Ref. 125). Even though the time scales are different, in both cases crystallization does not happen uniformly but with a steplike behavior (indicated by the arrows).

Image of FIG. 9.
FIG. 9.

Superlinear behavior of the damage vs dose for a implant into at room temperature. Symbols represent the maximum defect concentration as extracted from channeling spectra. The solid line is to highlight the trend. Regions I, II, and III can be clearly observed. The dashed line is the maximum value in the concentration profile of the Frenkel pair predicted by TRIM (from Ref. 93).

Image of FIG. 10.
FIG. 10.

Relative increment of the refractive index of as a function of the dose for 80 keV irradiations at room temperature with several ions. Regions I, II, and III are also observed (from Ref. 111).

Image of FIG. 11.
FIG. 11.

Number of displaced atoms as measured with RBS in situ after implantation of , , , , and at . The number of displaced atoms increase more than linearly as indicated by the dashed line (from Ref. 127).

Image of FIG. 12.
FIG. 12.

Critical amorphizing dose as a function of the implantation energy for several ions at (from Ref. 168). Solid lines are theoretical curves assuming the critical energy density model (described in Sec. V A).

Image of FIG. 13.
FIG. 13.

Logarithmic plot of the critical dose for amorphization vs for several ion types. The temperature at which amorphization is possible at a given dose shifts to higher values as the ion mass increases (from Ref. 163).

Image of FIG. 14.
FIG. 14.

Relative change of the refractive index vs dose for irradiated by (Ref. 121), (Ref. 20), and (Ref. 11) ions at target temperatures of , and (from Ref. 112).

Image of FIG. 15.
FIG. 15.

The dose of ions needed to produce a buried amorphous layer vs substrate temperature. Data are shown for several current densities (from Ref. 169).

Image of FIG. 16.
FIG. 16.

Relative damage yield as a function of the substrate temperature for irratiations to a fixed fluence of at several dose rates (from Ref. 100).

Image of FIG. 17.
FIG. 17.

Crystal-amorphous transition temperatures for (100) irradiated with ions to a fluence of using several ion types as a function of dose rate. The data points for carbon are for irradiations to (from Ref. 169).

Image of FIG. 18.
FIG. 18.

The damaged region surrounding the path of a high energy ion in a crystalline solid idealized as a cylinder (dashed lines). Defects escape from the outer sheath and only the inner core (solid lines) becomes amorphous (from Ref. 163).

Image of FIG. 19.
FIG. 19.

Fraction of amorphous area vs dose for various ions, , , and , implanted at either room temperature (RT) or liquid nitrogen temperature (LT). Computer calculated curves from Eq. (5) are shown as solid lines with the corresponding parameters and (from Ref. 64).

Image of FIG. 20.
FIG. 20.

Atomic structure of the cluster formed by four self-interstitials which has been considered as the amorphous embryo in electron irradiation experiments. It introduces in the lattice the typical five- and seven-membered rings of the amorphous phase (from Ref. 190).

Image of FIG. 21.
FIG. 21.

(a) Basic structural unit for showing the six-membered ring. A -split di-interstitial is shown by the dotted line and the atomic sites , , and . (b) Local atomic rearrangement after introducing a pair. Atomic sites 3, 4, 5, and form a five-membered ring and 3, , and give a part of a seven-membered ring (from Ref. 178).

Image of FIG. 22.
FIG. 22.

Atomic structure of the IV pair. Dashed lines represent atoms and bonds in the perfect lattice. Atoms and move along the directions indicated by the arrows and switch their bonds with atoms and , giving rise to the IV pair. Bond lengths involved in the defect are displayed in Table II.

Image of FIG. 23.
FIG. 23.

Kinklike steps at the interface. The lower part of the figure (gray) represents crystal, while the upper part is amorphous. The (001) interface is composed of {111} oriented terraces; along the [110] ledges , presenton this terraced structure, kink steps form. The motion of these kinks (indicated by arrows) produces crystallization (from Ref. 153).

Image of FIG. 24.
FIG. 24.

Time evolution of the potential energy per atom in lattice samples with 10%, 20%, 25%, and 30% of IV pairs during the annealing at different temperatures. Solid lines indicate the mean potential energy per atom in and at each temperature, and , respectively. Arrows indicate plateaus followed by steep decreases, due to the more stable structures formed by the interaction of several IV pairs.

Image of FIG. 25.
FIG. 25.

Radial distribution functions corresponding to a lattice with an IV pair concentration of 30% (solid line) and to a pure amorphous matrix (dotted line), both thermalized at .

Image of FIG. 26.
FIG. 26.

Snapshots taken during the annealing at of samples with the same amount of IV pairs (8%), scattered in one case and concentrated in the other. Each IV pair is introduced in the lattice by randomly choosing two neighboring atoms and displacing them as shown in Fig. 22. The scattered damage has disappeared after 10 ps of annealing, while the concentrated damage has barely shrunk.

Image of FIG. 27.
FIG. 27.

Arrhenius plot of the recrystallization velocity in samples with scattered and concentrated damage. The recrystallization velocity of a planar interface is also shown. Lines are best fits to each data set. Activation energies are represented besides the corresponding line.

Image of FIG. 28.
FIG. 28.

Scheme of the damage morphology. Each gray circle represents a IV pair, and the dashed lines their interaction radius. Isolated IV pairs annihilate first as they do not have any IV neighbor. The amorphous pockets start recombining by the outer IV pairs ( and ) as the inner ones ( or ) have more IV neighbors. IV pairs in the interface of elongated pockets recombine before than IV pairs in rounded pockets as they are surrounded by less IV neighbors. When a IV pair in a planar structure recombines (IV pair missing between and ) the whole layer regrows as the surrounding defects ( or ) have less IV neighbors than the other defects in the layer .

Image of FIG. 29.
FIG. 29.

Dose dependence of the damage produced by ions at room temperature. Solid and dashed lines correspond to the single-alingment (SA) and double-alignment (DA) Rutherford backscattering spectra from experiments of Ref. 165, respectively. Symbols represent our simulation results.

Image of FIG. 30.
FIG. 30.

Amorphous fraction vs substrate temperature for implants to a dose of with several dose rates (in ). Solid symbols correspond to the experimental data of Ref. 100, obtained from Rutherford backscattering spectra. Solid lines represent our simulation results.

Image of FIG. 31.
FIG. 31.

Critical temperature as a function of ion dose rate for and implants to a dose of . Open symbols correspond to simulation results. Solid symbols are from the experiments of Ref. 169.

Image of FIG. 32.
FIG. 32.

Damage evolution of a implant to a dose of . Black and dark gray points represent self-interstitials and vacancies, respectively. Light gray points correspond to IV pairs. (a) Damage after implantation at room temperature. (b) Damage during the temperature ramp. (c) Defects resulting after annealing at .

Image of FIG. 33.
FIG. 33.

Damage evolution of a implant to a dose of . Black and dark gray points represent self-interstitials and vacancies, respectively. Light gray points correspond to IV pairs. (a) Damage after implantation at room temperature. (b) The damage annealing at shows the planar regrowth of the continuous amorphous layer. Defects within this layer are swept out as the regrowth takes place. Defects beyond the original interface remains. (c) Defects resulting after annealing at .

Image of FIG. 34.
FIG. 34.

Residual damage profile after a 200 s anneal at for implants to doses of , , and . All implants are carried out with a dose rate of and at a substrate temperature of .

Image of FIG. 35.
FIG. 35.

Residual damage profile after a 200 s anneal at for implants at substrate temperature of 20 and . Both implants were carried out to a dose of with a dose rate of .

Tables

Generic image for table
Table I.

Thermodynamic and kinetic data for (after Refs. 73 and 84).

Generic image for table
Table II.

Lengths of the bonds involved in the IV pair and its formation energy, as obtained by using different simulation techniques: TB from Ref. 194, ab initio from Ref. 195, and classical MD using the Tersoff 3 potential (Ref. 201) from Ref. 200. Bond notation corresponds to that shown in Fig. 22.

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/content/aip/journal/jap/96/11/10.1063/1.1808484
2004-11-22
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Ion-beam-induced amorphization and recrystallization in silicon
http://aip.metastore.ingenta.com/content/aip/journal/jap/96/11/10.1063/1.1808484
10.1063/1.1808484
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